Existing law, until January 1, 2030, generally prohibits a person from possessing, importing, shipping, or transporting in the state, or from placing, planting, or causing to be placed or planted in any water within the state, invasive mussels, and authorizes the Director of Fish and Wildlife, or the directors designee, to engage in various enforcement activities with regard to invasive mussels. Existing law, until January 1, 2030, requires a public or private agency that operates a water supply system to cooperate with the Department of Fish and Wildlife to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that occurs in a water supply system. Existing law requires any person, or federal, state, or local agency, district, or authority that owns or manages a reservoir, where specified activities are permitted, except as specified, to develop and implement a program designed to prevent the introduction of invasive mussel species, as provided. Existing law requires any entity that discovers invasive mussels within the state to immediately report the discovery to the department.

This bill would prohibit a public agency from prohibiting imported water deliveries for groundwater replenishment, as defined, due to invasive mussels if the importation complies with a specified invasive mussel control plan and unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

The bill would include findings that changes proposed by this bill address a matter of statewide concern rather than a municipal affair and, therefore, apply to all cities and counties, including charter cities and charter counties.

Existing law, until January 1, 2030, generally prohibits a person from possessing, importing, shipping, or transporting in the state, or from placing, planting, or causing to be placed or planted in any water within the state, invasive mussels, and authorizes the Director of Fish and Wildlife, or the directors designee, to engage in various enforcement activities with regard to invasive mussels. Existing law, until January 1, 2030, requires a public or private agency that operates a water supply system to cooperate with the department Department of Fish and Wildlife to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that occurs in a water supply system. Existing law requires any person, or federal, state, or local agency, district, or authority that owns or manages a reservoir, where specified activities are permitted, except as specified, to develop and implement a program designed to prevent the introduction of invasive mussel species, as provided. Existing law requires any entity that discovers invasive mussels within the state to immediately report the discovery to the Department of Fish and Wildlife. department.

This bill would prohibit a public agency from prohibiting imported water deliveries, as defined, deliveries for groundwater replenishment replenishment, as defined, due to invasive mussels if the importation complies with a specified invasive mussel control plan and unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

The bill would include findings that changes proposed by this bill address a matter of statewide concern rather than a municipal affair and, therefore, apply to all cities and counties, including charter cities and charter counties.

Existing law, until January 1, 2030, generally prohibits a person from possessing, importing, shipping, or transporting in the state, or from placing, planting, or causing to be placed or planted in any water within the state, invasive mussels, and authorizes the Director of Fish and Wildlife, or the directors designee, to engage in various enforcement activities with regard to invasive mussels. Existing law, until January 1, 2030, requires a public or private agency that operates a water supply system to cooperate with the department to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that occurs in a water supply system. Existing law requires any person, or federal, state, or local agency, district, or authority that owns or manages a reservoir, where specified activities are permitted, except as specified, to develop and implement a program designed to prevent the introduction of invasive mussel species, as provided. Existing law requires any entity that discovers invasive mussels within the state to immediately report the discovery to the Department of Fish and Wildlife.

This bill would provide that, notwithstanding any other law, the state has exclusive authority to regulate invasive mussels. The bill would prohibit a city, county, district, or other local agency from adopting, enforcing, or implementing any ordinance, rule, regulation, policy, or other declaratory action pertaining to invasive mussels unless expressly authorized by state law. prohibit a public agency from prohibiting imported water deliveries, as defined, for groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

The bill would include findings that changes proposed by this bill address a matter of statewide concern rather than a municipal affair and, therefore, apply to all cities and counties, including charter cities and charter counties.

This bill would provide that, notwithstanding any other law, the state has exclusive authority to regulate invasive mussels. The bill would prohibit a city, county, district, or other local agency from adopting, enforcing, or implementing any ordinance, rule, regulation, policy, or other declaratory action pertaining to invasive mussels unless expressly authorized by state law.

Existing law generally prohibits the sale, possession, importation, transportation, transfer, live release, or giving away without consideration, of the salt water algae of the genus Caulerpa. Existing law authorizes a person to possess, for bona fide scientific research, as determined by, and upon authorization of, the Department of Fish and Wildlife, salt water algae of the genus Caulerpa.

This bill would make nonsubstantive changes to this law.

GOVERNOR'S VETO

GV Bill Id:AB 1894

Author:(Blanca Rubio)

As Enrolled Ver:August 24, 2026

2/3 vote

SUMMARY

Prevents a public agency from prohibiting groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

Governor's Veto Message

"This bill would prohibit a public agency from denying imported water for groundwater replenishment due to the presence of an invasive mussel.

In response to the detection of golden mussels in October 2024, my administration immediately began working with managers of uninfested and infested waters to support the implementation of invasive mussel prevention and containment programs. This work is critical to ensure that water managers are prepared to respond to the ongoing threat these species pose.

While I appreciate the author's intent, I am concerned by this bill's 'one-size-fits-all' approach prohibiting the denial of local water deliveries. This could have serious, unintended consequences for water managers statewide, especially as the challenges associated with invasive mussels continue to evolve."

COMMENTS

On October 17, 2024, Department of Water Resources (DWR) staff discovered golden mussels in the Port of Stockton. Soon after the initial discovery, the golden mussel was quickly found at additional sites within the Sacramento-San Joaquin Delta (Delta). The golden mussel is a freshwater bivalve native to the rivers and creeks of China and Southeast Asia, but it has established itself outside of its native range in several countries. The presence of the species poses a significant and immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure, and water quality. Economic impacts include costly repairs and maintenance (e.g., boats, water infrastructure, hydroelectric facilities), reduced water flow affecting food production, water delivery to homes, and flood control. According to the Administration's budget change proposal regarding golden mussels, "if allowed to spread further, golden mussel will affect every household in California, and every sector of our economy."

In 2025, the County of Los Angeles (County), fearing mussel infestation from imported water, prohibited water imports from infested waters, prioritizing protection of infrastructure over groundwater recharge. As a result, several agencies within the County have been unable to recharge groundwater with imported water from the State Water Project to replenish groundwater supplies. However, the disruption of groundwater recharge will likely put strain on local agencies and the communities they serve.

Los Angeles County Department of Public Works and Los Angeles County Flood Control District (LACFCD) own and operate spreading basins onto which the County spreads water, including stormwater. Imported water for groundwater replenishment is delivered through the flood control channels and diverted and spread at spreading grounds through agreements between water agencies and the County. At least two of the agreements between LACFCD and local agencies contain language granting LACFCD discretion to "allow, disallow, or restrict the spreading of imported water at the spreading grounds." The two agreements may be indicative of arrangements LACFCD has with other local agencies and also include the following provisions:

"[LACFCD] shall have full power and authority, at its sole and absolute discretion, to withdraw, modify, or revoke any permission granted in response to a written request when, in [LACFCD's] sole opinion, the spreading […] cannot or should not be performed due to [LACFCD's] operational and/or maintenance concerns, problems, or difficulties."

"[LACFCD] reserves the right to prohibit or to terminate the spreading of imported water at any time, without prior notice, in connection with any emergency that may exist."

"[The entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom."

"[LACFCD] reserves the right to cease the spreading of supplemental water at any time […] if, in the judgment of [LACFCD], such action shall be warranted by, and in connection with any emergency condition."

According to the author's office, the imported water deliveries of Burbank Water and Power were suspended on May 14, 2025, due to the presence of quagga mussels in the imported water system. Burbank Water and Power has an approved quagga control plan. The San Gabriel Valley agencies' imported water deliveries were suspended on September 24, 2025, due to County concerns about the infestation of Santa Fe Spreading Basins and San Gabriel Canyon Spreading Grounds with golden mussel. These water agencies are in the process of finalizing a golden mussel control plan to submit to the Department of Fish and Wildlife (CDFW).

Additionally, the San Gabriel Groundwater Basin went through a groundwater adjudication many decades ago and is governed by a court-mandated Physical Solution under the 1973 Main San Gabriel Judgment that expressly relies on the continued delivery of imported water to offset native overdraft and maintain basin sustainability. Imported water is not discretionary; it is a foundational element of the Physical Solution adopted by the Court to protect groundwater reliability, prevent further overdraft, and ensure long-term basin management.

On March 24, 2026, the County claims to have "officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys" with additional monitoring and interim safeguards. Sponsors of this measure indicate that this has not been the case in practice, but negotiations and agreements for pilot projects are underway between some water agencies and the County to treat water for golden mussels before the water is moved through infrastructure to the spreading grounds. There is still concern among water agencies that spreading will be prohibited in the future and agencies are currently developing additional agreements or language to clarify how spreading would be conducted under the risk of invasive mussels.

According to the Author

"Right now, water agencies in [the County] are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

[This bill] ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California's commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive golden mussel."

Arguments in Support

A coalition of southern California water agencies write in support of this bill. They note that "water agencies and communities throughout [the County] rely on the combination of imported and local water supplies. Some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries." They fear that interruptions for water deliveries could jeopardize "basin stability and drinking water reliability for over 1.5 million residents in the San Gabriel region, of which, approximately 60% are identified as disadvantaged communities." They believe this bill "would assist with ending the prolonged interruption of imported supplies and establish clarification of the adherence of state law and regulatory guidelines when it comes to the preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species."

Arguments in Opposition

The County writes in opposition, expressing concern that this bill would "limit local authority to protect critical flood control infrastructure from invasive mussels." The County believes that accepting potentially infested water could "increase the risk of contamination, interfere with flood control operations, and complicate the County's ability to meet federal obligations," as well as result in "significant unfunded costs."

Valley Ag Water Coalition (VAWC) expresses an oppose unless amended position. VAWC further notes that this bill would likely create impractical and burdensome constraints for even routine operational decisions, unless those actions are expressly authorized in state law. VAWC writes "Local agencies are often best positioned to respond quickly and effectively to invasive species threats based on regional conditions, infrastructure vulnerabilities, and water supply needs. [This bill's] broad preemption of local authority would undermine that ability and could ultimately increase risks to water supply reliability rather than reduce them."

FISCAL COMMENTS

According to the Assembly Appropriations Committee, this bill will have "minor and absorbable costs to [CDFW], the Department of Parks and Recreation's Division of Boating and Waterways, and the State Water Resources Control Board."

VOTES

ASM WATER, PARKS, AND WILDLIFE: 13-0-0

YES: Papan, Jeff Gonzalez, Alanis, Alvarez, Ávila Farías, Bains, Bennett, Boerner, Caloza, Gallagher, Hart, Muratsuchi, Rogers

ASM APPROPRIATIONS: 14-0-1

YES: Wicks, Hoover, Arambula, Calderon, Caloza, Dixon, Fong, Mark González, Krell, Pacheco, Pellerin, Solache, Ta, Tangipa

ABS, ABST OR NV: Muratsuchi

ASSEMBLY FLOOR: 74-0-6

YES: Addis, Aguiar-Curry, Ahrens, Alanis, Alvarez, Ávila Farías, Bains, Bauer-Kahan, Berman, Boerner, Bryan, Calderon, Carrillo, Castillo, Connolly, Davies, DeMaio, Dixon, Elhawary, Ellis, Flora, Fong, Gabriel, Gallagher, Garcia, Gipson, Jeff Gonzalez, Mark González, Hadwick, Haney, Harabedian, Hart, Hoover, Irwin, Jackson, Johnson, Kalra, Krell, Lackey, Lee, Lowenthal, Macedo, McKinnor, Nguyen, Ortega, Pacheco, Papan, Patel, Patterson, Pellerin, Petrie-Norris, Quirk-Silva, Ramos, Ransom, Celeste Rodriguez, Michelle Rodriguez, Rogers, Blanca Rubio, Sanchez, Schiavo, Schultz, Sharp-Collins, Solache, Soria, Stefani, Ta, Tangipa, Valencia, Wallis, Ward, Wicks, Wilson, Zbur, Rivas

ABS, ABST OR NV: Arambula, Bennett, Bonta, Caloza, Chen, Muratsuchi

SENATE FLOOR: 40-0-0

YES: Allen, Alvarado-Gil, Archuleta, Arreguín, Ashby, Becker, Blakespear, Cabaldon, Caballero, Cervantes, Choi, Cortese, Dahle, Durazo, Gonzalez, Grayson, Grove, Hurtado, Jones, Laird, Limón, McGuire, McNerney, Menjivar, Niello, Ochoa Bogh, Padilla, Pérez, Reyes, Richardson, Rubio, Seyarto, Smallwood-Cuevas, Stern, Strickland, Umberg, Valladares, Wahab, Weber Pierson, Wiener

ASSEMBLY FLOOR: 77-0-2

YES: Addis, Aguiar-Curry, Ahrens, Alanis, Alvarez, Arambula, Ávila Farías, Bains, Bauer-Kahan, Bennett, Berman, Boerner, Bonta, Bryan, Calderon, Caloza, Carrillo, Castillo, Connolly, Davies, DeMaio, Dixon, Elhawary, Ellis, Flora, Fong, Garcia, Gipson, Jeff Gonzalez, Mark González, Hadwick, Haney, Harabedian, Hart, Hoover, Irwin, Jackson, Johnson, Kalra, Krell, Lackey, Lee, Lowenthal, Macedo, McKinnor, Muratsuchi, Nguyen, Ortega, Pacheco, Papan, Patel, Patterson, Pellerin, Petrie-Norris, Quirk-Silva, Ramos, Ransom, Celeste Rodriguez, Michelle Rodriguez, Rogers, Blanca Rubio, Sanchez, Schiavo, Schultz, Sharp-Collins, Solache, Soria, Stefani, Ta, Tangipa, Valencia, Wallis, Ward, Wicks, Wilson, Zbur, Rivas

ABS, ABST OR NV: Chen, Gabriel

UPDATED

VERSION: August 24, 2026

CONSULTANT: Stephanie Mitchell / W., P., & W. / (916) 319-2096 FN: 0004588

CONCURRENCE IN SENATE AMENDMENTS

CSA1 Bill Id:AB 1894

Author:(Blanca Rubio)

As Amended Ver:May 28, 2026

Majority vote

SUMMARY

Prevents a public agency from prohibiting groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

Senate Amendments

Provides that water deliveries for groundwater replenishment are made in compliance with an approved invasive mussel control plan.

COMMENTS

On October 17, 2024, Department of Water Resources (DWR) staff discovered golden mussels in the Port of Stockton. Soon after the initial discovery, the golden mussel was quickly found at additional sites within the Sacramento-San Joaquin Delta (Delta). The golden mussel is a freshwater bivalve native to the rivers and creeks of China and Southeast Asia, but it has established itself outside of its native range in several countries. The presence of the species poses a significant and immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure, and water quality. Economic impacts include costly repairs and maintenance (e.g., boats, water infrastructure, hydroelectric facilities), reduced water flow affecting food production, water delivery to homes, and flood control. According to the Administration's budget change proposal regarding golden mussels, "if allowed to spread further, golden mussel will affect every household in California, and every sector of our economy."

In 2025, the County of Los Angeles (County), fearing mussel infestation from imported water, prohibited water imports from infested waters, prioritizing protection of infrastructure over groundwater recharge. As a result, several agencies within the County have been unable to recharge groundwater with imported water from the State Water Project to replenish groundwater supplies. However, the disruption of groundwater recharge will likely put strain on local agencies and the communities they serve.

Los Angeles County Department of Public Works and Los Angeles County Flood Control District (LACFCD) own and operate spreading basins onto which the County spreads water, including stormwater. Imported water for groundwater replenishment is delivered through the flood control channels and diverted and spread at spreading grounds through agreements between water agencies and the County. At least two of the agreements between LACFCD and local agencies contain language granting LACFCD discretion to "allow, disallow, or restrict the spreading of imported water at the spreading grounds." The two agreements may be indicative of arrangements LACFCD has with other local agencies and also include the following provisions:

"[LACFCD] shall have full power and authority, at its sole and absolute discretion, to withdraw, modify, or revoke any permission granted in response to a written request when, in [LACFCD's] sole opinion, the spreading […] cannot or should not be performed due to [LACFCD's] operational and/or maintenance concerns, problems, or difficulties."

"[LACFCD] reserves the right to prohibit or to terminate the spreading of imported water at any time, without prior notice, in connection with any emergency that may exist."

"[The entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom."

"[LACFCD] reserves the right to cease the spreading of supplemental water at any time […] if, in the judgment of [LACFCD], such action shall be warranted by, and in connection with any emergency condition."

According to the author's office, the imported water deliveries of Burbank Water and Power were suspended on May 14, 2025, due to the presence of quagga mussels in the imported water system. Burbank Water and Power has an approved quagga control plan. The San Gabriel Valley agencies' imported water deliveries were suspended on September 24, 2025, due to County concerns about the infestation of Santa Fe Spreading Basins and San Gabriel Canyon Spreading Grounds with golden mussel. These water agencies are in the process of finalizing a golden mussel control plan to submit to the Department of Fish and Wildlife (CDFW).

Additionally, the San Gabriel Groundwater Basin went through a groundwater adjudication many decades ago and is governed by a court-mandated Physical Solution under the 1973 Main San Gabriel Judgment that expressly relies on the continued delivery of imported water to offset native overdraft and maintain basin sustainability. Imported water is not discretionary; it is a foundational element of the Physical Solution adopted by the Court to protect groundwater reliability, prevent further overdraft, and ensure long-term basin management.

On March 24, 2026, the County claims to have "officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys" with additional monitoring and interim safeguards. Sponsors of this measure indicate that this has not been the case in practice, but negotiations and agreements for pilot projects are underway between some water agencies and the County to treat water for golden mussels before the water is moved through infrastructure to the spreading grounds. There is still concern among water agencies that spreading will be prohibited in the future and agencies are currently developing additional agreements or language to clarify how spreading would be conducted under the risk of invasive mussels.

According to the Author

"Right now, water agencies in [the County] are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

[This bill] ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California's commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive golden mussel."

Arguments in Support

A coalition of southern California water agencies write in support of this bill. They note that "water agencies and communities throughout [the County] rely on the combination of imported and local water supplies. Some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries." They fear that interruptions for water deliveries could jeopardize "basin stability and drinking water reliability for over 1.5 million residents in the San Gabriel region, of which, approximately 60% are identified as disadvantaged communities." They believe this bill "would assist with ending the prolonged interruption of imported supplies and establish clarification of the adherence of state law and regulatory guidelines when it comes to the preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species."

Arguments in Opposition

The County writes in opposition, expressing concern that this bill would "limit local authority to protect critical flood control infrastructure from invasive mussels." The County believes that accepting potentially infested water could "increase the risk of contamination, interfere with flood control operations, and complicate the County's ability to meet federal obligations," as well as result in "significant unfunded costs."

Valley Ag Water Coalition (VAWC) expresses an oppose unless amended position. VAWC further notes that this bill would likely create impractical and burdensome constraints for even routine operational decisions, unless those actions are expressly authorized in state law. VAWC writes "Local agencies are often best positioned to respond quickly and effectively to invasive species threats based on regional conditions, infrastructure vulnerabilities, and water supply needs. [This bill's] broad preemption of local authority would undermine that ability and could ultimately increase risks to water supply reliability rather than reduce them."

FISCAL COMMENTS

According to the Assembly Appropriations Committee, this bill will have "minor and absorbable costs to [CDFW], the Department of Parks and Recreation's Division of Boating and Waterways, and the State Water Resources Control Board."

VOTES:

ASM WATER, PARKS, AND WILDLIFE: 13-0-0

YES: Papan, Jeff Gonzalez, Alanis, Alvarez, Ávila Farías, Bains, Bennett, Boerner, Caloza, Gallagher, Hart, Muratsuchi, Rogers

ASM APPROPRIATIONS: 14-0-1

YES: Wicks, Hoover, Arambula, Calderon, Caloza, Dixon, Fong, Mark González, Krell, Pacheco, Pellerin, Solache, Ta, Tangipa

ABS, ABST OR NV: Muratsuchi

ASSEMBLY FLOOR: 74-0-6

YES: Addis, Aguiar-Curry, Ahrens, Alanis, Alvarez, Ávila Farías, Bains, Bauer-Kahan, Berman, Boerner, Bryan, Calderon, Carrillo, Castillo, Connolly, Davies, DeMaio, Dixon, Elhawary, Ellis, Flora, Fong, Gabriel, Gallagher, Garcia, Gipson, Jeff Gonzalez, Mark González, Hadwick, Haney, Harabedian, Hart, Hoover, Irwin, Jackson, Johnson, Kalra, Krell, Lackey, Lee, Lowenthal, Macedo, McKinnor, Nguyen, Ortega, Pacheco, Papan, Patel, Patterson, Pellerin, Petrie-Norris, Quirk-Silva, Ramos, Ransom, Celeste Rodriguez, Michelle Rodriguez, Rogers, Blanca Rubio, Sanchez, Schiavo, Schultz, Sharp-Collins, Solache, Soria, Stefani, Ta, Tangipa, Valencia, Wallis, Ward, Wicks, Wilson, Zbur, Rivas

ABS, ABST OR NV: Arambula, Bennett, Bonta, Caloza, Chen, Muratsuchi

SENATE FLOOR: 40-0-0

YES: Allen, Alvarado-Gil, Archuleta, Arreguín, Ashby, Becker, Blakespear, Cabaldon, Caballero, Cervantes, Choi, Cortese, Dahle, Durazo, Gonzalez, Grayson, Grove, Hurtado, Jones, Laird, Limón, McGuire, McNerney, Menjivar, Niello, Ochoa Bogh, Padilla, Pérez, Reyes, Richardson, Rubio, Seyarto, Smallwood-Cuevas, Stern, Strickland, Umberg, Valladares, Wahab, Weber Pierson, Wiener

UPDATED

VERSION: May 28, 2026

CONSULTANT: Stephanie Mitchell / W., P., & W. / (916) 319-2096 FN: 0003737

CONCURRENCE IN SENATE AMENDMENTS

CSA1 Bill Id:AB 1894

Author:(Blanca Rubio)

As Amended Ver:May 28, 2026

Majority vote

SUMMARY

Prevents a public agency from prohibiting groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

Senate Amendments

Provides that water deliveries for groundwater replenishment are made in compliance with an approved invasive mussel control plan.

COMMENTS

On October 17, 2024, Department of Water Resources (DWR) staff discovered golden mussels in the Port of Stockton. Soon after the initial discovery, the golden mussel was quickly found at additional sites within the Sacramento-San Joaquin Delta (Delta). The golden mussel is a freshwater bivalve native to the rivers and creeks of China and Southeast Asia, but it has established itself outside of its native range in several countries. The presence of the species poses a significant and immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure, and water quality. Economic impacts include costly repairs and maintenance (e.g., boats, water infrastructure, hydroelectric facilities), reduced water flow affecting food production, water delivery to homes, and flood control. According to the Administration's budget change proposal regarding golden mussels, "if allowed to spread further, golden mussel will affect every household in California, and every sector of our economy."

In 2025, the County of Los Angeles (County), fearing mussel infestation from imported water, prohibited water imports from infested waters, prioritizing protection of infrastructure over groundwater recharge. As a result, several agencies within the County have been unable to recharge groundwater with imported water from the State Water Project to replenish groundwater supplies. However, the disruption of groundwater recharge will likely put strain on local agencies and the communities they serve.

Los Angeles County Department of Public Works and Los Angeles County Flood Control District (LACFCD) own and operate spreading basins onto which the County spreads water, including stormwater. Imported water for groundwater replenishment is delivered through the flood control channels and diverted and spread at spreading grounds through agreements between water agencies and the County. At least two of the agreements between LACFCD and local agencies contain language granting LACFCD discretion to "allow, disallow, or restrict the spreading of imported water at the spreading grounds." The two agreements may be indicative of arrangements LACFCD has with other local agencies and also include the following provisions:

"[LACFCD] shall have full power and authority, at its sole and absolute discretion, to withdraw, modify, or revoke any permission granted in response to a written request when, in [LACFCD's] sole opinion, the spreading […] cannot or should not be performed due to [LACFCD's] operational and/or maintenance concerns, problems, or difficulties."

"[LACFCD] reserves the right to prohibit or to terminate the spreading of imported water at any time, without prior notice, in connection with any emergency that may exist."

"[The entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom."

"[LACFCD] reserves the right to cease the spreading of supplemental water at any time […] if, in the judgment of [LACFCD], such action shall be warranted by, and in connection with any emergency condition."

According to the author's office, the imported water deliveries of Burbank Water and Power were suspended on May 14, 2025, due to the presence of quagga mussels in the imported water system. Burbank Water and Power has an approved quagga control plan. The San Gabriel Valley agencies' imported water deliveries were suspended on September 24, 2025, due to County concerns about the infestation of Santa Fe Spreading Basins and San Gabriel Canyon Spreading Grounds with golden mussel. These water agencies are in the process of finalizing a golden mussel control plan to submit to the Department of Fish and Wildlife (CDFW).

Additionally, the San Gabriel Groundwater Basin went through a groundwater adjudication many decades ago and is governed by a court-mandated Physical Solution under the 1973 Main San Gabriel Judgment that expressly relies on the continued delivery of imported water to offset native overdraft and maintain basin sustainability. Imported water is not discretionary; it is a foundational element of the Physical Solution adopted by the Court to protect groundwater reliability, prevent further overdraft, and ensure long-term basin management.

On March 24, 2026, the County claims to have "officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys" with additional monitoring and interim safeguards. Sponsors of this measure indicate that this has not been the case in practice, but negotiations and agreements for pilot projects are underway between some water agencies and the County to treat water for golden mussels before the water is moved through infrastructure to the spreading grounds. There is still concern among water agencies that spreading will be prohibited in the future and agencies are currently developing additional agreements or language to clarify how spreading would be conducted under the risk of invasive mussels.

According to the Author

"Right now, water agencies in [the County] are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

[This bill] ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California's commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive golden mussel."

Arguments in Support

A coalition of southern California water agencies write in support of this bill. They note that "water agencies and communities throughout [the County] rely on the combination of imported and local water supplies. Some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries." They fear that interruptions for water deliveries could jeopardize "basin stability and drinking water reliability for over 1.5 million residents in the San Gabriel region, of which, approximately 60% are identified as disadvantaged communities." They believe this bill "would assist with ending the prolonged interruption of imported supplies and establish clarification of the adherence of state law and regulatory guidelines when it comes to the preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species."

Arguments in Opposition

The County writes in opposition, expressing concern that this bill would "limit local authority to protect critical flood control infrastructure from invasive mussels." The County believes that accepting potentially infested water could "increase the risk of contamination, interfere with flood control operations, and complicate the County's ability to meet federal obligations," as well as result in "significant unfunded costs."

Valley Ag Water Coalition (VAWC) expresses an oppose unless amended position. VAWC further notes that this bill would likely create impractical and burdensome constraints for even routine operational decisions, unless those actions are expressly authorized in state law. VAWC writes "Local agencies are often best positioned to respond quickly and effectively to invasive species threats based on regional conditions, infrastructure vulnerabilities, and water supply needs. [This bill's] broad preemption of local authority would undermine that ability and could ultimately increase risks to water supply reliability rather than reduce them."

FISCAL COMMENTS

According to the Assembly Appropriations Committee, this bill will have "minor and absorbable costs to [CDFW], the Department of Parks and Recreation's Division of Boating and Waterways, and the State Water Resources Control Board."

VOTES:

ASM WATER, PARKS, AND WILDLIFE: 13-0-0

YES: Papan, Jeff Gonzalez, Alanis, Alvarez, Ávila Farías, Bains, Bennett, Boerner, Caloza, Gallagher, Hart, Muratsuchi, Rogers

ASM APPROPRIATIONS: 14-0-1

YES: Wicks, Hoover, Arambula, Calderon, Caloza, Dixon, Fong, Mark González, Krell, Pacheco, Pellerin, Solache, Ta, Tangipa

ABS, ABST OR NV: Muratsuchi

ASSEMBLY FLOOR: 74-0-6

YES: Addis, Aguiar-Curry, Ahrens, Alanis, Alvarez, Ávila Farías, Bains, Bauer-Kahan, Berman, Boerner, Bryan, Calderon, Carrillo, Castillo, Connolly, Davies, DeMaio, Dixon, Elhawary, Ellis, Flora, Fong, Gabriel, Gallagher, Garcia, Gipson, Jeff Gonzalez, Mark González, Hadwick, Haney, Harabedian, Hart, Hoover, Irwin, Jackson, Johnson, Kalra, Krell, Lackey, Lee, Lowenthal, Macedo, McKinnor, Nguyen, Ortega, Pacheco, Papan, Patel, Patterson, Pellerin, Petrie-Norris, Quirk-Silva, Ramos, Ransom, Celeste Rodriguez, Michelle Rodriguez, Rogers, Blanca Rubio, Sanchez, Schiavo, Schultz, Sharp-Collins, Solache, Soria, Stefani, Ta, Tangipa, Valencia, Wallis, Ward, Wicks, Wilson, Zbur, Rivas

ABS, ABST OR NV: Arambula, Bennett, Bonta, Caloza, Chen, Muratsuchi

UPDATED

VERSION: May 28, 2026

CONSULTANT: Stephanie Mitchell / W., P., & W. / (916) 319-2096 FN: 0003737

 THIRD READING  

Bill No: AB 1894

Author: Blanca Rubio (D)

Amended: 5/28/26 in Senate

Vote: 21

SENATE NATURAL RES. & WATER COMMITTEE: 7-0, 6/9/26

AYES: Becker, Seyarto, Allen, Cabaldon, Grove, Laird, Reyes

SENATE APPROPRIATIONS COMMITTEE: Senate Rule 28.8

ASSEMBLY FLOOR: 74-0, 5/4/26 - See last page for vote

SUBJECT: Fish and wildlife: invasive mussels: imported water

SOURCE: San Gabriel Valley Municipal Water District

Upper San Gabriel Valley Municipal Water Distrct

DIGEST:

This bill prevents a public agency from prohibiting imported water deliveries for groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

ANALYSIS:

Existing law:

1. Prohibits, until January 1, 2030, a person from possessing, importing, shipping, or transporting in the state, or placing, planting, or causing to be placed or planted in any water within the state, invasive mussels (Fish and Game Code (FGC) §2301(a)).
2. Requires a public or private agency that operates a water supply system to cooperate with the California Department of Fish and Wildlife (CDFW) to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that may occur in a water supply system. Requires the operator of the water supply system, if invasive mussels are detected, and in cooperation with CDFW to prepare and implement a plan to control or eradicate invasive mussels within the system, and eliminate or minimize any potential downstream transport of an invasive mussel (FGC §2301(d)).
   1. Requires all plans that do not specifically address invasive mussel species that are known to be present in bodies of water in the state as of January 1, 2026, to be updated or revised on or before September 30, 2027.
3. Requires any entity that discovers invasive mussels within the state to immediately report the discovery to CDFW (FGC §2301(e)).
4. Makes any person who violates the above provisions, violates any verbal or written order or regulation adopted pursuant to these provisions, or who resists, delays, obstructs, or interferes with the implementation of these provisions subject to an administrative penalty (FGC §2301(f)).
5. Defines “invasive mussel” as any nonnative detrimental mussel species that is capable of spreading in freshwater and is listed in specific regulations adopted by the Fish and Game Commission (FGC §2303).

This bill:

1. Prevents a public agency from prohibiting imported water deliveries for groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.
2. Defines “imported water deliveries for groundwater replenishment” as deliveries of water imported from outside a region’s local watershed or natural boundary, primarily originating from the State Water Project, the Colorado River, or the Eastern Sierra, where the water is to be used for managed aquifer recharge, groundwater rejection, spreading, percolation, or other activities intended to replenish groundwater supplies.
3. Specifies, for purposes of this bill, that water includes, but is not limited to, surface water conveyed by an aqueduct, canal, pipeline, or other conveyance.
4. Finds and declares that this bill addresses a matter of statewide concern and applies to all cities and counties, including charter cities and charter counties.

Comments

Recent author amendments. Recent author amendments limit the bill’s application to imported water deliveries for groundwater replenishment that are made in compliance with an approved invasive mussel control plan. Specifically, unless there is a proven health and safety risk, a public agency would not be able to prohibit the importation of water for groundwater replenishment that is made in compliance with an CDFW-approved invasive mussel control plan.

But, what if? Despite adherence to a CDFW-approved invasive mussel control plan, it is still possible that invasive mussels can make their way to groundwater recharge facilities. Such instances are typically governed by the contractual agreement between the delivering and receiving entities. For example, in LAFCD’s agreement, "[the entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom.” Thus, if water imported from the SWP were to contain invasive mussels that damaged the facility, the San Gabriel Valley Municipal Water District would be responsible for mitigating the situation.

It is unknown whether all water agencies and receiving agencies that would be impacted by this bill have similar provisions within their agreements.

See Senate Natural Resources and Water Committee policy analysis of this bill for complete background information.

FISCAL EFFECT: Appropriation: No Fiscal Com.: Yes Local: No

SUPPORT: (Verified 6/22/2026)

San Gabriel Valley Municipal Water District (Co-source)

Upper San Gabriel Valley Municipal Water District (Co-source)

Burbank Water and Power
California Municipal Utilities Association
City of Azusa
San Gabriel Valley Council of Governments
San Gabriel Valley Economic Partnership
San Gabriel Valley Water Association
Three Valleys Municipal Water District

OPPOSITION: (Verified 6/22/2026)

None received

ARGUMENTS IN SUPPORT: According to the author, “[s]everal water agencies in Los Angeles County are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

“AB 1894 ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California’s commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive Golden Mussel.”

According to a coalition letter representing various water agencies, including the co-sponsors of the bill, AB 1894 would “establish clarification of the adherence of state law and regulatory guidelines when it comes to preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species.” Additionally, “the interruption of the imported water delivers also threatens the 1973 Main San Gabriel Basin Groundwater Adjudication, which expressly relies on the continued delivery of imported water to offset overdraft and maintain sustainability. Imported water deliveries are not discretionary for the Basin; it is a fundamental element of the groundwater adjudication’s physical solution.”

ARGUMENTS IN OPPOSITION: According to the Valley Ag Water Coalition, writing in an opposed unless amended position, there are 4 main issues. First, “the bill usurps the authority of a groundwater recharge facility owner to protect its investment in design, permitting, and construction of the facility, and removes control of the facility from the owner by requiring it to accept the importation of water supplies from known infested bodies of water.”

Second, the bill’s “broad preemption of local authority could ultimately increase risks to water supply reliability by importing invasive mussels into an area that is not infested. … AB 1894 would expose … areas to infestation of golden mussels through the forced importation of State Water Project supplies from the north.”

Third, “if invasive mussels are detected, the operator of the water supply system – not the entity importing the water – would be required to prepare and implement a plan to control or eradicate invasive mussels within the system … . AB 1894, in effect, shifts the burden from the entity creating the problem to the operator of the water supply system that [accepts the water].”

Finally, the coalition argues that “[golden mussels] are not directly known to pose a direct threat to human health, but they do create significant safety and infrastructure risks that can be indirectly affect public well-being. Therefore, the health and safety risk exception provided …would be unlikely to ever apply.”

ASSEMBLY FLOOR: 74-0, 5/4/26

AYES: Addis, Aguiar-Curry, Ahrens, Alanis, Alvarez, Ávila Farías, Bains, Bauer-Kahan, Berman, Boerner, Bryan, Calderon, Carrillo, Castillo, Connolly, Davies, DeMaio, Dixon, Elhawary, Ellis, Flora, Fong, Gabriel, Gallagher, Garcia, Gipson, Jeff Gonzalez, Mark González, Hadwick, Haney, Harabedian, Hart, Hoover, Irwin, Jackson, Johnson, Kalra, Krell, Lackey, Lee, Lowenthal, Macedo, McKinnor, Nguyen, Ortega, Pacheco, Papan, Patel, Patterson, Pellerin, Petrie-Norris, Quirk-Silva, Ramos, Ransom, Celeste Rodriguez, Michelle Rodriguez, Rogers, Blanca Rubio, Sanchez, Schiavo, Schultz, Sharp-Collins, Solache, Soria, Stefani, Ta, Tangipa, Valencia, Wallis, Ward, Wicks, Wilson, Zbur, Rivas

NO VOTE RECORDED: Arambula, Bennett, Bonta, Caloza, Chen, Muratsuchi

Prepared by: Genevieve Wong / N.R. & W. / (916) 651-4116

6/24/26 16:32:20

**** END ****

SENATE COMMITTEE ON NATURAL RESOURCES AND WATER

Senator Josh Becker, Chair

2025 - 2026 Regular

Bill No: AB Hearing Date: June 9, 2026

Subject: Fish and wildlife: invasive mussels: imported water

SUMMARY

This bill would prevent a public agency from prohibiting imported water deliveries for groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

BACKGROUND AND EXISTING LAW

Mussel mania.

Invasive mussel legislative history. Since 2007, California has been working to control and eradicate two species of invasive, freshwater mussels in state waters: quagga and zebra (dreissenid) mussels. In response to dreissenid mussel infestation, the Legislature has passed a series of bills that established the dreissenid mussels as restricted species and granted the California Department of Fish and Wildlife (CDFW) with authorities to inspect, order treatment, and quarantine water vessels. As a restricted species, a person is prohibited from possessing, importing, shipping, transporting, or introducing the dreissenid mussels in any water within the state, unless authorized by CDFW through a restricted species permit.

Further, statute requires water managers to work with CDFW to develop measures to avoid infestation, as well as requires water managers to develop control plans to prevent the spread of the invasive mussels should the water system become infested with the mussels. The benefit of developing a control plan is that water managers enjoy liability protections from the unintentional transportation or introduction of dreissenid mussels to the water system once the control plan is approved by CDFW.

Several years later, the Legislature established the Quagga and Zebra Mussel Infestation Program. Under the program, an additional fee is charged to motorized boats in the state since motor boat recreation is thought to be the most likely cause of over-land aquatic invasive species spreading. Revenues from the fee are primarily used for grants distributed by the Division of Boating and Waterways (DBW), within the Department of Parks and Recreation (State Parks). The next round of grants for the program are currently open, and DBW expects to distribute up to $2 million dollars. The grants are available to entities that own or manage any aspect of water in a reservoir that is open for public recreation and is mussel-free. The funds must be used for prevention projects, such as planning, watercraft inspection stations and inspectors, launch monitors, watercraft decontamination units, educational signage, and outreach.

Until last year, statute and state programming was specific to quagga and zebra mussels. AB 149 (Committee on Budget, Chapter 106, Statutes of 2025) expanded the dreissenid mussel programs and authorities to include any invasive mussel, including the golden mussel.

Say hello to my little friend, the golden mussel. On October 17, 2024, Department of Water Resources (DWR) staff discovered golden mussels in the Port of Stockton. Soon after the initial discovery, the golden mussel was quickly found at additional sites within the Sacramento-San Joaquin Delta (Delta). The golden mussel is a freshwater bivalve native to the rivers and creeks of China and Southeast Asia, but it has established itself outside of its native range in several countries. The discovery in Stockton was the first detection of the species in the United States. The Fish and Game Commission quickly took emergency action to add “Limnoperna fortunei (golden mussel)” to the list of restricted species. Since then, the golden mussel has been detected throughout the Delta and the State Water Project.

The presence of the species poses a significant and immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure, and water quality. Environmental impacts of the golden mussel include loss of native and game fish through competition for food sources as well as a contribution to harmful algal blooms. It is estimated that a single mussel can filter up to a liter of water a day, which would remove critical nutrients and microbes that support ecosystem health. Recreation impacts of this mussel include waterbody closures, mandatory inspections, increased launch and/or entry fees, and reduced numbers of fish and shellfish for consumption. Economic impacts include costly repairs and maintenance (e.g., boats, water infrastructure, hydroelectric facilities), reduced water flow affecting food production, water delivery to homes, and flood control.

Don’t move a mussel. Golden mussels have proven to be much more difficult for the state and water managers to control. Golden mussels have high reproductive rates and form dense colonies. This mass colonization of surfaces (termed “biofouling”) blocks, impairs, and, in many cases, inhibits the functionality of manmade surfaces including underwater intakes, structures, and mechanisms. Biofouling also coats the hulls and external components of watercraft and recreational facilities, and natural objects such as rocks, fallen trees, even other sedentary bivalves. In addition, mass colonies of golden mussels alter ecological processes of the natural environment resulting in detrimental impacts to native and game species and water quality. Nearly every fresh and brackish waterbody in California is suitable habitat for golden mussels.

There are no socially and environmentally benign methods currently available to eliminate invasive mussels once they are present. Adult mussels can survive days, even weeks, when removed from water. Larval mussels can survive a week or longer in small volumes of water. Eradication from large, interconnected bodies of water is likely impossible. Therefore, containing mussels within infested areas is the only means to minimize additional new, widespread impacts.

Invasive mussels control plan. Public and private agencies that operate a water supply system are required to cooperate with CDFW to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that may occur in the system. If invasive mussels are detected, the operator of the water supply system is required to prepare a plan, subject to CDFW approval, to control or eradicate invasive mussels in the system and eliminate or minimize any potential downstream transport of an invasive mussel. The plans are required to include methods for delineation of infestation; methods for control or eradication of adult mussels and decontamination of water containing larval mussels; a system monitoring program; and a requirement that the operator of the water supply system allows CDFW inspections as well as cooperates with CDFW to update or revise control or eradication measures in the plan to address scientific advancements.

One county’s response. In 2025, the County of Los Angeles (County), fearing mussel infestation from imported water, prohibited water imports from infested waters. As a result, several agencies within the County have been unable to recharge groundwater with imported water from the State Water Project to replenish groundwater supplies. However, water agencies and communities throughout the county rely on a combination of imported and local water supplies, and some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries.

Los Angeles County Department of Public Works and Los Angeles County Flood Control District (LACFCD) own and operate spreading basins onto which the County spreads water, including stormwater. Imported water for groundwater replenishment is delivered through the flood control channels and diverted and spread at spreading grounds through agreements between water agencies and the County. At least two of the agreements between LACFCD and local agencies contain language granting LACFCD discretion to “allow, disallow, or restrict the spreading of imported water at the spreading grounds.” The two agreements may be indicative of arrangements LACFCD has with other local agencies and also include the following provisions:

"[LACFCD] shall have full power and authority, at its sole and absolute discretion, to withdraw, modify, or revoke any permission granted in response to a written request when, in [LACFCD's] sole opinion, the spreading […] cannot or should not be performed due to [LACFCD's] operational and/or maintenance concerns, problems, or difficulties."

"[LACFCD] reserves the right to prohibit or to terminate the spreading of imported water at any time, without prior notice, in connection with any emergency that may exist."

"[The entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom."

"[LACFCD] reserves the right to cease the spreading of supplemental water at any time […] if, in the judgment of [LACFCD], such action shall be warranted by, and in connection with any emergency condition."

According to the author's office, the imported water deliveries of Burbank Water and Power were suspended on May 14, 2025, due to the presence of quagga mussels in the imported water system. Burbank Water and Power has an approved quagga control plan. The San Gabriel Valley agencies’ imported water deliveries were suspended on September 24, 2025, due to County concerns about the infestation of Santa Fe Spreading Basins and San Gabriel Canyon Spreading Grounds with golden mussel. These water agencies are in the process of finalizing their golden mussel control plans to submit to the CDFW.

Additionally, the San Gabriel Groundwater Basin went through a groundwater adjudication many decades ago and is governed by a court-mandated Physical Solution under the 1973 Main San Gabriel Judgment that expressly relies on the continued delivery of imported water to offset native overdraft and maintain basin sustainability. For the San Gabriel Groundwater Basin, imported water is not discretionary; it is a foundational element of the Physical Solution adopted by the Court to protect groundwater reliability, prevent further overdraft, and ensure long-term basin management.

According to the author, on March 24, 2026, the County claims to have “officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys” with additional monitoring and interim safeguards. Sponsors of this measure indicate that while the moratorium has been lifted, no water deliveries have been approved. A pilot project for the Upper Canyon Spreading Basin in the San Gabriel Valley is pending control plan approval and water quality permits. For Burbank Water and Power, an invasive species control plan has been approved, but there is no set date for water deliveries to resume. There remains concern among water agencies regarding the timing of when spreading will be allowed, and work continues on Upper San Gabriel Valley Municipal Water District’s control plan for deliveries to the greater San Gabriel Valley.

Existing law:

1. Until January 1, 2030, prohibits a person from possessing, importing, shipping, or transporting in the state, or placing, planting, or causing to be placed or planted in any water within the state, invasive mussels (Fish and Game Code (FGC) §2301(a)).
   
2. Requires a public or private agency that operates a water supply system to cooperate with CDFW to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that may occur in a water supply system. Requires the operator of the water supply system, if invasive mussels are detected, and in cooperation with CDFW to prepare and implement a plan to control or eradicate invasive mussels within the system, and eliminate or minimize any potential downstream transport of an invasive mussel (FGC §2301(d)).
   
   1. Requires all plans that do not specifically address invasive mussel species that are known to be present in bodies of water in the state as of January 1, 2026, to be updated or revised on or before September 30, 2027.
      
3. Requires any entity that discovers invasive mussels within the state to immediately report the discovery to CDFW (FGC §2301(e)).
   
4. Makes any person who violates the above provisions, violates any verbal or written order or regulation adopted pursuant to these provisions, or who resists, delays, obstructs, or interferes with the implementation of these provisions subject to an administrative penalty (FGC §2301(f)).
   
5. Defines “invasive mussel” as any nonnative detrimental mussel species that is capable of spreading in freshwater and is listed in specific regulations adopted by the Fish and Game Commission (FGC §2303).

PROPOSED LAW

This bill would:

1. Prevent a public agency from prohibiting imported water deliveries for groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.
   
2. Define “imported water deliveries for groundwater replenishment” as deliveries of water imported from outside a region’s local watershed or natural boundary, primarily originating from the State Water Project, the Colorado River, or the Eastern Sierra, where the water is to be used for managed aquifer recharge, groundwater rejection, spreading, percolation, or other activities intended to replenish groundwater supplies.
   
3. Specify, for purposes of the bill, that water includes, but is not limited to, surface water conveyed by an aqueduct, canal, pipeline, or other conveyance.
   
4. Finds and declares that the bill addresses a matter of statewide concern and applies to all cities and counties, including charter cities and charter counties.

ARGUMENTS IN SUPPORT

According to the author, “[s]everal water agencies in Los Angeles County are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

“AB 1894 ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California’s commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive Golden Mussel.”

According to a coalition letter representing various water agencies, including the co-sponsors of the bill, AB 1894 would “establish clarification of the adherence of state law and regulatory guidelines when it comes to preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species.” Additionally, “the interruption of the imported water delivers also threatens the 1973 Main San Gabriel Basin Groundwater Adjudication, which expressly relies on the continued delivery of imported water to offset overdraft and maintain sustainability. Imported water deliveries are not discretionary for the Basin; it is a fundamental element of the groundwater adjudication’s physical solution.”

ARGUMENTS IN OPPOSITION

According to the Valley Ag Water Coalition, writing in an opposed unless amended position, there are 4 main issues. First, “the bill usurps the authority of a groundwater recharge facility owner to protect its investment in design, permitting, and construction of the facility, and removes control of the facility from the owner by requiring it to accept the importation of water supplies from known infested bodies of water.”

Second, the bill’s “broad preemption of local authority could ultimately increase risks to water supply reliability by importing invasive mussels into an area that is not infested. … AB 1894 would expose … areas to infestation of golden mussels through the forced importation of State Water Project supplies from the north.”

Third, “if invasive mussels are detected, the operator of the water supply system – not the entity importing the water – would be required to prepare and implement a plan to control or eradicate invasive mussels within the system … . AB 1894, in effect, shifts the burden from the entity creating the problem to the operator of the water supply system that [accepts the water].”

Finally, the coalition argues that “[golden mussels] are not directly known to pose a direct threat to human health, but they do create significant safety and infrastructure risks that can be indirectly affect public well-being. Therefore, the health and safety risk exception provided …would be unlikely to ever apply.”

COMMENTS

Recent author amendments. Recent author amendments limit the bill’s application to imported water deliveries for groundwater replenishment that are made in compliance with an approved invasive mussel control plan. Specifically, unless there is a proven health and safety risk, a public agency would not be able to prohibit the importation of water for groundwater replenishment that is made in compliance with an CDFW-approved invasive mussel control plan.

Existing law requires all plans that do not specifically address all invasive mussel species known to be present in the state as of January 1, 2026 (which would include golden mussels) to be revised and updated by September 30, 2027. However, if this bill is enacted, it will take effect January 1, 2027, almost 9 months before the plans are required to be updated. It is unclear if all impacted water agencies would have an updated control plan submitted to CDFW by this time. Additionally, it is noted that, under existing law, CDFW is required to approve or provide comments to any revised plan within 180 days of the plan’s submission. If an updated plan is not submitted to CDFW until September 30, 2027, and CDFW has an additional 180 days to respond to the plan, this would add to the potential gap between when the bill takes effect and when imported water deliveries in compliance with a control plan could take advantage of the bill’s safeguard against local restriction. However, the gap may be appropriate to ensure adequate control plans are in place and being implemented given the serious consequences that would result from the infestation of invasive mussels.

But, what if? Despite adherence to a CDFW-approved invasive mussel control plan, it is still possible that invasive mussels can make their way to groundwater recharge facilities. Such instances are typically governed by the contractual agreement between the delivering and receiving entities. For example, in LAFCD’s agreement, "[the entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom.” Thus, if water imported from the SWP were to contain invasive mussels that damaged the facility, the San Gabriel Valley Municipal Water District would be responsible for mitigating the situation.

It is unknown whether all water agencies and receiving agencies that would be impacted by this bill have similar provisions within their agreements.

Related legislation

AB 1772 (Papan), of the current legislative session, would authorize CDFW to decontaminate or order the decontamination of a conveyance found or reasonably believed to harbor aquatic invasive species after conducting a specified inspection. AB 1772 is pending referral in the Senate Rules Committee.

AB 2032 (Ransom), of the current legislative session, would require CDFW, the Department of Pesticide Regulation, the State Water Resources Control Board, and the Regional Water Quality Controls Boards to take various actions to quickly and effectively respond to invasive golden mussels. AB 2032 is pending referral in the Senate Rules Committee

AB 2787 (Committee on Water, Parks, and Wildlife), of the current legislative session, among other things, provides that a person who operates a Nevada-registered vessel on the waters of Lake Tahoe or Topaz Lake shall not be cited for operation of a vessel without a valid state-issued invasive mussel sticker, provided that Nevada has a program in effect for the management of aquatic invasive species. AB 2787 is pending in this Committee.

AB 149 (Committee on Budget, Chapter 106, Statutes of 2025), among other things, expanded statute and programs from “dreissenid mussels” to “invasive mussels,” establishes a requirement for CDFW to review and approve updated invasive mussel control plans, and increased the invasive mussel fee.

AB 1150 (Committee on Water, Parks, and Wildlife, Chapter 831, Statutes of 2023), among other things, distinguished that the issuance and collection of the quagga and zebra mussel infestation and prevention fee from the biennial registration renewal.

AB 2443 (Williams, Chapter 485, Statutes of 2012), establishes the quagga and zebra mussel infestation prevention program, which required payment of the invasive mussel fee on vessels and permitted the use of the funds for, among other things, a grant program.

AB 1929 (Hall, Chapter 152, Statutes of 2010) determines that a water operator is indemnified from the penalty of possessing and transporting a restricted species, if the water operator is in compliance with an approved control plan.

AB 2065 (Hancock), Chapter 667, Statutes of 2008, requires reservoir managers to undertake certain measures to prevent invasive mussel infestation in reservoirs in which invasives mussels have not been detected.

AB 1683 (Wolk), Chapter 419, Statutes of 2007, prohibits a person to possess, import, ship, or transport in the state, or place, plant, or cause to be placed or planted in any water within the state, dreissenid mussels, unless authorized by CDFW. Additionally, authorizes the Director of CDFW, or the Director’s designee, to conduct inspections of conveyances (e.g., vehicles and boats), order that the conveyance be drained, dried, or decontaminated, impound or quarantine conveyances, and conduct inspections of waters of the state and facilities that may contain invasive mussels. Further, requires water operators to implement measures to avoid dreissenid mussel infestation and develop a control plan upon infestation, among other things.

SUGGESTED AMENDMENTS: NONE

SUPPORT

San Gabriel Valley Municipal Water District (co-sponsor)

Upper San Gabriel Valley Municipal Water District (co-sponsor)

Azuza Light and Water

California Municipal Utilities Association

San Gabriel Valley Economic Partnership

San Gabriel Valley Water Association

Three Valleys Municipal Water District

OPPOSITION

Valley Ag Water Association (unless amended)

-- END --

ASSEMBLY THIRD READING

ATR Bill Id:AB 1894

Author:(Blanca Rubio)

As Amended Ver:April 16, 2026

Majority vote

SUMMARY

Prevents a public agency from prohibiting groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

Major Provisions

1. Defines "imported water deliveries for groundwater replenishment" for the purpose of this bill.
2. Finds and declares that the regulation, control, management, and eradication of invasive mussels are matters of statewide concern.

COMMENTS

On October 17, 2024, Department of Water Resources (DWR) staff discovered golden mussels in the Port of Stockton. Soon after the initial discovery, the golden mussel was quickly found at additional sites within the Sacramento-San Joaquin Delta (Delta). The golden mussel is a freshwater bivalve native to the rivers and creeks of China and Southeast Asia, but it has established itself outside of its native range in several countries. The presence of the species poses a significant and immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure, and water quality. Economic impacts include costly repairs and maintenance (e.g., boats, water infrastructure, hydroelectric facilities), reduced water flow affecting food production, water delivery to homes, and flood control. According to the Administration's budget change proposal regarding golden mussels, "if allowed to spread further, golden mussel will affect every household in California, and every sector of our economy."

In 2025, the County of Los Angeles (County), fearing mussel infestation from imported water, prohibited water imports from infested waters, prioritizing protection of infrastructure over groundwater recharge. As a result, several agencies within the County have been unable to recharge groundwater with imported water from the State Water Project to replenish groundwater supplies. However, the disruption of groundwater recharge will likely put strain on local agencies and the communities they serve.

Los Angeles County Department of Public Works and Los Angeles County Flood Control District (LACFCD) own and operate spreading basins onto which the County spreads water, including stormwater. Imported water for groundwater replenishment is delivered through the flood control channels and diverted and spread at spreading grounds through agreements between water agencies and the County. At least two of the agreements between LACFCD and local agencies contain language granting LACFCD discretion to "allow, disallow, or restrict the spreading of imported water at the spreading grounds." The two agreements may be indicative of arrangements LACFCD has with other local agencies and also include the following provisions:

"[LACFCD] shall have full power and authority, at its sole and absolute discretion, to withdraw, modify, or revoke any permission granted in response to a written request when, in [LACFCD's] sole opinion, the spreading […] cannot or should not be performed due to [LACFCD's] operational and/or maintenance concerns, problems, or difficulties."

"[LACFCD] reserves the right to prohibit or to terminate the spreading of imported water at any time, without prior notice, in connection with any emergency that may exist."

"[The entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD's] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom."

"[LACFCD] reserves the right to cease the spreading of supplemental water at any time […] if, in the judgment of [LACFCD], such action shall be warranted by, and in connection with any emergency condition."

According to the author's office, the imported water deliveries of Burbank Water and Power were suspended on May 14, 2025, due to the presence of quagga mussels in the imported water system. Burbank Water and Power has an approved quagga control plan. The San Gabriel Valley agencies' imported water deliveries were suspended on September 24, 2025, due to County concerns about the infestation of Santa Fe Spreading Basins and San Gabriel Canyon Spreading Grounds with golden mussel. These water agencies are in the process of finalizing a golden mussel control plan to submit to the Department of Fish and Wildlife (CDFW).

Additionally, the San Gabriel Groundwater Basin went through a groundwater adjudication many decades ago and is governed by a court-mandated Physical Solution under the 1973 Main San Gabriel Judgment that expressly relies on the continued delivery of imported water to offset native overdraft and maintain basin sustainability. Imported water is not discretionary; it is a foundational element of the Physical Solution adopted by the Court to protect groundwater reliability, prevent further overdraft, and ensure long-term basin management.

On March 24, 2026, the County claims to have "officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys" with additional monitoring and interim safeguards. Sponsors of this measure indicate that this has not been the case in practice, but negotiations and agreements for pilot projects are underway between some water agencies and the County to treat water for golden mussels before the water is moved through infrastructure to the spreading grounds. There is still concern among water agencies that spreading will be prohibited in the future and agencies are currently developing additional agreements or language to clarify how spreading would be conducted under the risk of invasive mussels.

According to the Author

"Right now, water agencies in Los Angeles County are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities."

"[This bill] ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California's commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive golden mussel."

Arguments in Support

A coalition of southern California water agencies write in support of this bill. They note that "water agencies and communities throughout Los Angeles County rely on the combination of imported and local water supplies. Some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries." They fear that interruptions for water deliveries could jeopardize "basin stability and drinking water reliability for over 1.5 million residents in the San Gabriel region, of which, approximately 60% are identified as disadvantaged communities." They believe this bill "would assist with ending the prolonged interruption of imported supplies and establish clarification of the adherence of state law and regulatory guidelines when it comes to the preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species."

Arguments in Opposition

Valley Ag Water Coalition (VAWC) expresses an oppose unless amended position. VAWC acknowledges the challenges the sponsors of the bill are facing: "Absent the ability to import State Water Project supplies for recharge, basin producers could be forced to significantly reduce groundwater pumping or seek alternative and potentially more costly recharge options." VAWC further notes that this bill would likely create impractical and burdensome constraints for even routine operational decisions, unless those actions are expressly authorized in state law. VAWC writes "Local agencies are often best positioned to respond quickly and effectively to invasive species threats based on regional conditions, infrastructure vulnerabilities, and water supply needs. [This bill's] broad preemption of local authority would undermine that ability and could ultimately increase risks to water supply reliability rather than reduce them."

FISCAL COMMENTS

According to the Assembly Appropriations Committee, this bill will have "minor and absorbable costs to [CDFW], the Department of Parks and Recreation's Division of Boating and Waterways, and the State Water Resources Control Board."

"As part of the Governor's fiscal year (FY) 2026-27 budget, CDFW is requesting eight permanent positions to increase [CDFW's] capacity to prevent the spread of golden mussel from infested waters. The administration intends to fund these positions for three years from $20 million appropriated to the department in the 2025 Budget Act."

VOTES

ASM WATER, PARKS, AND WILDLIFE: 13-0-0

YES: Papan, Jeff Gonzalez, Alanis, Alvarez, Ávila Farías, Bains, Bennett, Boerner, Caloza, Gallagher, Hart, Muratsuchi, Rogers

ASM APPROPRIATIONS: 14-0-1

YES: Wicks, Hoover, Arambula, Calderon, Caloza, Dixon, Fong, Mark González, Krell, Pacheco, Pellerin, Solache, Ta, Tangipa

ABS, ABST OR NV: Muratsuchi

UPDATED

VERSION: April 16, 2026

CONSULTANT: Stephanie Mitchell / W., P., & W. / (916) 319-2096 FN: 0002464

Date of Hearing: April 29, 2026

ASSEMBLY COMMITTEE ON APPROPRIATIONS

Buffy Wicks, Chair

ABPCA Bill Id:AB 1894

Author:(Blanca Rubio) – As Amended Ver:April 16, 2026

Urgency: No State Mandated Local Program: No Reimbursable: No

SUMMARY:

This bill prohibits a public agency from prohibiting imported water deliveries for groundwater replenishment due to invasive mussels unless there is substantial, documented evidence of a proven health and safety risk as a result of the invasive mussels.

The bill defines “imported water deliveries for groundwater replenishment” as deliveries of water imported from outside a region’s local watershed or natural boundary, primarily originating from the State Water Project, the Colorado River, or the Eastern Sierra, where the water is to be used for managed aquifer recharge, groundwater injection, spreading, percolation, or other activities intended to replenish groundwater supplies. For purposes of this definition, “water” includes, but is not limited to, surface water conveyed by an aqueduct, canal, pipeline, or other conveyance.

FISCAL EFFECT:

Minor and absorbable costs to the California Department of Fish and Wildlife (CDFW), the Department of Parks and Recreation’s Division of Boating and Waterways (DBW), and the State Water Resources Control Board.

As part of the Governor’s fiscal year (FY) 2026-27 budget, CDFW is requesting eight permanent positions to increase the department’s capacity to prevent the spread of golden mussel from infested waters. The administration intends to fund these positions for three years from $20 million appropriated to the department in the 2025 Budget Act.

COMMENTS:

1) Purpose. According to the author:

While water agencies in Los Angeles County have been told that imported water deliveries have now resumed, there remains significant concern about the reliability of those assurances for the future. Agencies faced serious disruptions in delivering imported water needed to replenish groundwater for six months, despite complying with state law and developing approved plans to address invasive mussels. These uncertainties undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

This bill ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California’s commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive golden mussel.

2) Background. Golden Mussel. According to CDFW, golden mussel is an invasive bivalve. Adult mussels form byssal threads that enable them to attach to surfaces and spawn multiple times each year, producing thousands of offspring. In October 2024, golden mussels were discovered in the Sacramento-San Joaquin Delta – the first known occurrence in North America. Since then, golden mussels have been detected throughout the Delta and the State Water Project (SWP).

Golden mussels have been linked to a loss of native and game fish, because they compete for the same food sources, and contribute to harmful fish-killing algal blooms. Recreational impacts include waterbody closures, mandatory inspections, increased boat launch or entry fees, and reduced numbers of fish and shellfish for consumption. Economic impacts include costly repairs and maintenance (boats, water infrastructure, hydroelectric facilities) and reduced water flow affecting food production, water delivery to homes, and flood control.

The most common way invasive mussels move between waterbodies is by hitchhiking on watercraft and equipment. According to CDFW, there are no socially and environmentally benign methods currently available to eliminate invasive mussels once they are present. Therefore, containing mussels within infested areas is the only means to minimize additional new, widespread impacts. While the spread of invasive mussels in interconnected waters cannot be prevented without restricting navigation, their overland spread, attached to and within watercraft and equipment, can be prevented.

Since the discovery of golden mussels in the state, CDFW has been coordinating with other agencies to survey the extent of infestation in the Delta, sample for golden mussel in waters statewide, and update existing outreach and education material to include golden mussel. CDFW also formed an interagency Golden Mussel Task Force that developed a statewide Golden Mussel Response Framework in April 2025. This proposal to respond to golden mussels builds upon the department’s existing capacity within the Invasive Species Program’s Quagga and Zebra Mussel Project that has successfully contained quagga mussel within Southern California since 2007. Under this project, motorized boats pay an infestation prevention fee (via a sticker issued by the Department of Motor Vehicles), and revenues from the fee are primarily used for grants distributed by DBW. The current sticker is collected every two years, and as of January 2026, the current fee for the sticker is $16 and expires at the same time as the vessel registration renewal sticker. To date, in fiscal year 2025-26, CDFW has collected approximately $2.5 million in fees, and DBW expects to award up to $2 million in grants to eligible applicants in 2026.

Budget trailer language in 2025, among other things, extended the state’s quagga and zebra mussel protections to golden mussels, expanded the current mussel sticker fee to include golden mussels, and allowed the fee to increase from $30 to up to $42.

To date, sticker fees have not been used for golden mussels; however, DBW is promulgating emergency regulations to comply with last year’s budget trailer language – specifically to change the name of the current grant program to add golden mussels and to establish a technical advisory group to increase the sticker fee to enable a more robust response to the invasion of the golden mussel.

Imported Water Deliveries. In 2025, Los Angeles County, fearing mussel infestation from imported water, prohibited water imports from infested waters. As a result, several agencies within the county were unable to recharge groundwater with imported water from the SWP to replenish groundwater supplies. This has been a challenge, because water agencies and communities throughout the county rely on a combination of imported and local water supplies, and some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries.

On March 24, 2026, the county claimed to have “officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys” with additional monitoring and interim safeguards. Sponsors of this bill indicate this has not been the case in practice, but negotiations and agreements for pilot projects are underway between some water agencies and the county to treat water for golden mussels before water is moved through infrastructure to the spreading grounds. There is still concern among water agencies that spreading will be prohibited in the future, and agencies are currently developing additional agreements or language to clarify how spreading will be conducted under the risk of invasive mussels.

Analysis Prepared by: Nikita Koraddi / APPR. / (916) 319-2081

Date of Hearing: April 14, 2026

ASSEMBLY COMMITTEE ON WATER, PARKS, AND WILDLIFE

Diane Papan, Chair

ABPCA Bill Id:AB 1894 (

Author:Blanca Rubio) – As Amended Ver:March 16, 2026

SUBJECT: Fish and wildlife: invasive mussels

SUMMARY: Declares that the state shall retain exclusive authority to regulate invasive mussels. Specifically, this bill:

1. Finds and declares that the regulation, control, management, and prevention of the introduction, possession, spread, or eradication of invasive mussels, including, but not limited to, Dreissena rostriformis bugensis, commonly known as quagga mussels, Dreissena polymorpha, commonly known as zebra mussels, and Limnoperna fortunei, commonly known as golden mussels, is a matter of statewide concern.
2. Notwithstanding any other law, declares that the state shall retain exclusive authority to regulate invasive mussels.
3. Prohibits a city, county, district, or other local agency from adopting, enforcing, or implementing any ordinance, rule, regulation, policy, or other declaratory action pertaining to invasive mussels unless expressly authorized by state law.
4. Preempts and prevents from having force or effect any local ordinance, rule, or regulation that conflicts with this prohibition.
5. Clarifies that this prohibition does not preclude local agencies from cooperating with, or implementing measures required by, the California Department of Fish and Wildlife (CDFW) or other state agencies pursuant to state-approved invasive mussel prevention or control programs.
6. Finds and declares that Section 1 of this bill addresses a matter of statewide concern rather than a municipal affair as that term is used in Section 5 of Article XI of the California Constitution. Therefore, this bill applies to all cities and counties, including charter cities and charter counties.

EXISTING LAW:

1. Until January 1, 2030, prohibits a person from possessing, importing, shipping, or transporting in the state, or placing, planting, or causing to be placed or planted in any water within the state, invasive mussels, unless authorized by CDFW.
   1. Provides the Director of CDFW, or a designee of the Director, the authority to conduct inspections of conveyances (e.g., vehicles and boats), order that the conveyance be drained, dried, or decontaminated, impound or quarantine conveyances, and conduct inspections of waters of the state and facilities that may contain invasive mussels. Permits the Director of CDFW to determine that other parties or state agencies, including State Parks, the Department of Water Resources (DWR), the Department of Food and Agriculture (CDFA), and the State Lands Commission, may exercise those authorities as well.
   2. Exempts from the California Environmental Quality Act (CEQA), any action in Existing Law #1, above, but does not exempt from CEQA the use of chemicals, other than salt or hot water, to decontaminate a conveyance or facility.
   3. Requires a public or private agency that operates a water supply system (water operator) to cooperate with CDFW to implement measures to avoid infestation by invasive mussels and to control or eradicate any infestation that may occur in a water supply system. If invasive mussels are detected, the water operator, in cooperation with CDFW, shall prepare and implement a plan to control or eradicate invasive mussels within the system, and eliminate or minimize any potential downstream transport of an invasive mussel. Requires the approved plan to contain the following minimum elements:
      1. Methods for delineation of infestation, including both adult mussels and veligers;
      2. Methods for control or eradication of adult mussels and decontamination of water containing larval mussels;
      3. A systematic monitoring program to determine any changes in conditions; and
      4. The requirement that the water operator permit inspections by CDFW as well as cooperate with CDFW to update or revise control or eradication measures in the approved plan to address scientific advances in the methods of controlling or eradicating mussels and veligers.
   4. If the water operator has prepared, initiated, and is in compliance with all the elements of an approved plan to control or eradicate invasive mussels in accordance with Existing Law #1 (b), the restrictions of Existing Law #1, above, do not apply to the operation of those water delivery and storage facilities, and the water operator is not subject to any civil or criminal liability for the introduction of invasive mussel species as a result of those operations. Authorizes CDFW to require the water operator to update its plan. Authorizes CDFW to apply the restrictions on a water operator if the plan is not updated or revised, until the water operator updates or revises the plan.
   5. Requires CDFW, on or before December 31, 2026, to review all approved plans pursuant (c) and requires all plans that do not specifically address all invasive mussel species known to be present in bodies of water in the state as of January 1, 2026, to be updated or revised appropriately to include all invasive mussel species, on or before September 30, 2027.
   6. Requires every invasive mussel species to be addressed in a plan no later than 180 days from the date that the species is listed in a regulation. Requires CDFW to approve plans or provide written comments and suggestions on plan deficiencies within 180 days from the date of plan submission.
   7. Requires an entity that discovers invasive mussels within this state to immediately report the discovery to CDFW.
   8. Establishes an additional penalty for any violation of Existing Law #1 with a penalty not to exceed $1,000.
   9. Allows CDFW to adopt regulations to carry out the restrictions in Existing Law #1.
   10. Indemnifies CDFW and any other state agency exercising authority under Existing Law #1 with regard to any determination or authorization made pursuant to this section [Fish and Game Code (FGC) § 2301]
2. Requires any person, or federal, state, or local agency, district, or authority that owns or manages a reservoir (reservoir manager) to undertake certain measures to prevent invasive mussel infestation, in reservoirs in which invasives mussels have not been detected.
   1. Requires a reservoir manager responsible for a reservoir, where recreational, boating, or fishing activities are permitted, except a privately owned reservoir that is not open to the public, to:
      1. Assess the vulnerability of the reservoir for the introduction of invasive mussel species; and
      2. Develop and implement a program designed to prevent the introduction of invasive mussel species. Requires the program to, at a minimum, include public education, monitoring, and management of those recreational, boating, or fishing activities that are permitted.
   2. Requires a reservoir manager responsible for a reservoir, where recreational, boating, or fishing activities of any kind are not permitted, to include visual monitoring for the presence of mussels as part of its routine field activities, based on its available resources and staffing.
   3. Allows a reservoir manager, except a privately owned reservoir that is not open to the public, to refuse the planting of fish in that reservoir by CDFW unless CDFW can demonstrate that the fish planting does not present a risk of introducing invasive mussels.
   4. Establishes a civil penalty, not to exceed $1,000 per violation of Existing Law #2, above. Authorizes CDFW to adopt regulations to implement and enforce requirements on reservoir managers to the extent funds are available (FGC § 2302).
3. Defines “invasive mussel” to mean any nonnative detrimental mussel species that is capable of spreading in freshwater and is listed in a regulation adopted by the Fish and Game Commission (FGC § 2303).
4. Prohibits the importation, transportation, possession, or live release of specified wild animals into this state except under a revocable, nontransferable restricted species permit issued by CDFW, in cooperation with CDFA (FGC § 2116 et seq.; 14 California Code of Regulations 14 § 671 et seq.).
5. Provides civil and criminal penalties for violations of invasive mussel restrictions and any permit conditions (FGC §§ 2125 and12000).

FISCAL EFFECT: Unknown. This bill is keyed fiscal.

COMMENTS:

1. Purpose of this bill. According to the author, “Right now, water agencies in Los Angeles County are being blocked from delivering imported water needed to replenish groundwater despite complying with state law and developing approved plans to address invasive mussels. These disruptions undermine the court-ordered management of the Main San Gabriel Groundwater Basin and threaten the primary drinking water source for more than 1.5 million residents, many in disadvantaged communities.

[This bill] ensures that critical water decisions affecting the entire state are made consistently at the state level and not through a patchwork of conflicting local rules. By aligning policy with science and existing law, this bill protects our water supply, supports emergency response needs, and upholds California’s commitment to the human right to water while prioritizing strategies to mitigate the threats of the invasive golden mussel.”

1. Background. On October 17, 2024, DWR staff discovered golden mussels in the Port of Stockton. Soon after the initial discovery, the golden mussel was quickly found at additional sites within the Sacramento-San Joaquin Delta (Delta). The golden mussel is a freshwater bivalve native to the rivers and creeks of China and Southeast Asia, but it has established itself outside of its native range in several countries. The discovery in Stockton was the first detection of the species in the United States. The Fish and Game Commission quickly took emergency action to add “Limnoperna fortunei (golden mussel)” to the list of restricted species (species that cannot be imported, transported, or possessed within the state, except by a restricted species permit). Since then, the golden mussel has been detected throughout the Delta and the State Water Project.

Golden mussel detection map as of April 2026

The presence of the species poses a significant and immediate threat to the ecological health of the Delta and all waters of the state, water conveyance systems, infrastructure, and water quality. Environmental impacts of the golden mussel include loss of native and game fish through competition for food sources as well as a contribution to harmful algal blooms. It is estimated that a single mussel can filter up to a liter of water a day, which would remove critical nutrients and microbes that support ecosystem health. Recreational impacts of this mussel include waterbody closures, mandatory inspections, increased launch and/or entry fees, and reduced numbers of fish and shellfish for consumption. Economic impacts include costly repairs and maintenance (e.g., boats, water infrastructure, hydroelectric facilities), reduced water flow affecting food production, water delivery to homes, and flood control. According to the Administration’s budget change proposal regarding golden mussels, “if allowed to spread further, golden mussel will affect every household in California, and every sector of our economy.”

Invasive mussel legislative history. Since 2007, California has been working to control and eradicate two other species of invasive, freshwater mussels in state waters: quagga and zebra (dreissenid) mussels. In response to dreissenid mussel infestation, the Legislature has passed a series of bills that established the dreissenid mussels as restricted species, granted CDFW with authorities to inspect, order treatment, and quarantine water vessels. Since dreissenid mussels are restricted species, a person is prohibited from possessing, importing, shipping, transporting or introducing the dreissenid mussels in any water within the state, unless authorized by CDFW through a restricted species permit.

Further, statute requires water managers to work with CDFW to develop measures to avoid infestation, as well as requires water managers to develop control plans to prevent the spread of the invasive mussels should the water system become infested with the mussels. The benefit of developing a control plan is that water managers enjoy liability protections from the unintentional transportation or introduction of dreissenid mussels to the water system once the control plan is approved by CDFW.

Several years later, the Legislature established the Quagga and Zebra Mussel Infestation Program. Under the current program, an additional fee is charged to motorized boats in the state since motor boat recreation is thought to be the most likely cause of over-land aquatic invasive species spreading. Revenues from the fee are primarily used for grants distributed by DBW. The next round of grants for the program are currently open, and DBW expects to distribute up to $2 million dollars. The grants are available to entities that own or manage any aspect of water in a reservoir that is open for public recreation and is mussel-free. The funds must be used for prevention projects, such as planning, watercraft inspection stations and inspectors, launch monitors, watercraft decontamination units, educational signage, and outreach.

Until last year, statute, and therefore state programming, was specific to quagga and zebra mussels. In AB 149 (see Related Legislation, below), the dreissenid mussel programs and authorities were expanded to include any invasive mussel, which includes the golden mussel.

Don’t move a mussel. Golden mussels have proven to be much more difficult for the state and water managers to control. Golden mussels have high reproductive rates and form dense colonies. This mass colonization of surfaces (termed “biofouling”) blocks, impairs, and, in many cases, inhibits the functionality of manmade surfaces including underwater intakes, structures, and mechanisms. Biofouling also coats the hulls and external components of watercraft and recreational facilities, and natural objects such as rocks, fallen trees, even other sedentary bivalves. In addition, mass colonies of golden mussels alter ecological processes of the natural environment resulting in detrimental impacts to native and game species and water quality. Nearly every fresh and brackish waterbody in California is suitable for golden mussel to establish. Indeed, this Committee has heard of countless examples of the issues golden mussel infestation has been causing for water infrastructure and the recreational boating industry. Even the fear of infestation has resulted in water operators heavily restricting, or even prohibiting, water access for public recreation.

There are no socially and environmentally benign methods currently available to eliminate invasive mussels once they are present. Adult mussels can survive days, even weeks, when removed from water. Larval mussels can survive a week or longer in small volumes of water. Eradication from large, interconnected bodies of water is likely impossible. Therefore, containing mussels within infested areas is the only means to minimize additional new, widespread impacts.

Los Angeles County (County) muscling out golden mussels. In 2025, the County, fearing mussel infestation from imported water, prohibited water imports from infested waters, prioritizing protection of infrastructure over groundwater recharge. As a result, several agencies within the County are currently unable to recharge groundwater with imported water from the State Water Project to replenish groundwater supplies. However, the disruption of groundwater recharge will likely put strain on local agencies and the communities they serve.

Los Angeles County Department of Public Works and Los Angeles County Flood Control District (LACFCD) own and operate spreading basins onto which the County spreads water, including stormwater. Imported water for groundwater replenishment is delivered through the flood control channels and diverted and spread at spreading grounds through agreements between water agencies and the County. A couple of example agreements with LACFCD were provided to the Committee. It is unclear to the Committee if other agreements contain similar language; however, within these agreements, LACFCD retains its discretion to “allow, disallow, or restrict the spreading of imported water at the spreading grounds,” upon receiving a written request. The agreements also include the following provisions:

“[LACFCD] shall have full power and authority, at its sole and absolute discretion, to withdraw, modify, or revoke any permission granted in response to a written request when, in [LACFCD’s] sole opinion, the spreading […] cannot or should not be performed due to [LACFCD’s] operational and/or maintenance concerns, problems, or difficulties.”

“[LACFCD] reserves the right to prohibit or to terminate the spreading of imported water at any time, without prior notice, in connection with any emergency that may exist.”

“[The entity conducting the spreading] shall be responsible for and shall fully compensate and reimburse [LACFCD] immediately upon request in connection with any damage to [LACFCD’s] property or facilities caused directly or indirectly by the replenishment connection or any water flowing therefrom.”

“[LACFCD] reserves the right to cease the spreading of supplemental water at any time […] if, in the judgment of [LACFCD], such action shall be warranted by, and in connection with any emergency condition.”

Each agreement also contains language regarding LACFCD’s responsibility for the facilities, either: (1) requiring the water spreading entity to fully compensate and reimburse LACFCD for any damage caused, or (2) clarifying that there is no obligation for LACFCD to spend funds for the operations and maintenance of existing facilities. Both agreements reviewed by the Committee contain indemnification causes protecting both LACFCD and the spreading entity.

According to the author’s office, the imported water deliveries of Burbank Water and Power were suspended on May 14, 2025 due to the presence of quagga mussels in the imported water system. Burbank Water and Power has an approved quagga control plan. The San Gabriel Valley agencies’ imported water deliveries were suspended on September 24, 2025, due to County concerns of golden mussel infesting the Santa Fe Spreading Basins and San Gabriel Canyon Spreading Grounds. These water agencies are in the process of finalizing a golden mussel control plan to submit to CDFW. Additionally, the San Gabriel Groundwater Basin is governed by a court-mandated Physical Solution under the 1973 Main San Gabriel Judgment, which expressly relies on the continued delivery of imported water to offset native overdraft and maintain basin sustainability. Imported water is not discretionary; it is a foundational element of the Physical Solution adopted by the Court to protect groundwater reliability, prevent further overdraft, and ensure long-term basin management.

On March 24, 2026, the County claims to have “officially lifted its prohibition to allow for the gradual reintroduction of imported water to support groundwater recharge operations in the San Gabriel and San Fernando Valleys” with additional monitoring and interim safeguards. Sponsors of this measure indicate that this has not been the case in practice, but negotiations and agreements for pilot projects are underway between some water agencies and the County to treat water for golden mussels before water is moved through infrastructure to the spreading grounds. There is still concern among water agencies that spreading will be prohibited in the future and agencies are currently developing additional agreements or language to clarify how spreading would be conducted under the risk of invasive mussels.

1. Proposed committee amendments. This bill highlights the tension between the water needs of the state and the risk and expense of potential golden mussel infestation. As drafted, this bill creates broad exemptions from local authorities unless that authority is granted in state law. The Committee may wish for the author to narrow the bill to remove undirected limitations on local authority, with the following amendments:

2302.5. (a) The Legislature finds and declares that the regulation, control, management, and prevention of the introduction, possession, spread, or eradication of invasive mussels, including, but not limited to, Dreissena rostriformis bugensis, commonly known as quagga mussels, Dreissena polymorpha, commonly known as zebra mussels, and Limnoperna fortunei, commonly known as golden mussels, is a matter of statewide concern.

(b) (1) Notwithstanding any other law, the state shall retain exclusive authority to regulate invasive mussels.

(2) A city, county, district, or other local agency shall not adopt, enforce, or implement any ordinance, rule, regulation, policy, or other declaratory action pertaining to invasive mussels unless expressly authorized by state law.

(c) A local ordinance, rule, or regulation that conflicts with this section is preempted and has no force or effect.

(d) This section does not preclude local agencies from cooperating with, or implementing measures required by, the department or other state agencies pursuant to state-approved invasive mussel prevention or control programs.

(b) The imported water deliveries for groundwater replenishment shall not be prohibited by a public agency, due to invasive mussels, unless there is substantial, documented evidence of a proven health and safety risk as a result of invasive mussels.

(c) For purposes of this section, “imported water deliveries for groundwater replenishment” means deliveries of water imported from outside a region's local watershed or natural boundary, primarily originating from the State Water Project, the Colorado River, or the Eastern Sierra, where the water is to be used, including but not limited to surface water conveyed by aqueduct, canal, pipeline, or other conveyance, that are used for managed aquifer recharge, groundwater injection, spreading, percolation, or other activities intended to replenish groundwater supplies.

1. Arguments in support. A coalition of southern California water agencies write in support of this bill. They note that “water agencies and communities throughout Los Angeles County rely on the combination of imported and local water supplies. Some agencies, including Burbank Water and Power, are 100% reliant on imported water deliveries.” They fear that interruptions for water deliveries could jeopardize “basin stability and drinking water reliability for over 1.5 million residents in the San Gabriel region, of which, approximately 60% are identified as disadvantaged communities.” They believe this bill “would assist with ending the prolonged interruption of imported supplies and establish clarification of the adherence of state law and regulatory guidelines when it comes to the preventing, controlling, and eradicating of the newly immersed invasive golden mussel, along with other invasive species.”
2. Arguments in opposition. Both Valley Ag Water Coalition (VAWC) and the Solano County Board of Supervisors, express an oppose unless amended position. VAWC acknowledge the challenges the sponsors of the bill are facing: “Absent the ability to import State Water Project supplies for recharge, basin producers could be forced to significantly reduce groundwater pumping or seek alternative and potentially more costly recharge options.” However, both argue that the broad language in the bill would usurp local control. VAWC further notes that this bill would likely create impractical and burdensome constraints for even routine operation decisions, unless those actions are expressly authorized in state law. VAWC writes “Local agencies are often best positioned to respond quickly and effectively to invasive species threats based on regional conditions, infrastructure vulnerabilities, and water supply needs. [This bill’s] broad preemption of local authority would undermine that ability and could ultimately increase risks to water supply reliability rather than reduce them.”
3. Related legislation. AB 1772 (Papan) of the current legislative session requires CDFW, in consultation with State Parks and CDFW, to develop a voluntary framework to prevent the overland spread of invasive mussels through the conveyance of watercraft overland. AB 1772 is also set for hearing in this Committee.

AB 2032 (Ransom) of the current legislative session establishes exemptions for restricted species permits and scientific collection permits, for water operators with respect to golden mussels. Additionally, requires CDFW to develop and adopt best management practices for water operators to control the spread of golden mussels. Further, requires CDFW and the State and Regional Water Control Boards to expedite the evaluation of pesticides and any national pollutant discharge elimination system permits, respectively. AB 2032 is also set for hearing in this Committee.

AB 2787 (Committee on Water, Parks, and Wildlife) of the current legislative session, among other things, provides that a person who operates a Nevada-registered vessel on the waters of Lake Tahoe or Topaz Lake shall not be cited for operation of a vessel without a valid state-issued invasive mussel sticker, provided that Nevada has a program in effect for the management of aquatic invasive species. AB 2787 is also set for hearing in this Committee.

AB 149 (Committee on Budget), Chapter 106, Statutes of 2025, among other things, expanded statue and programs from “dreissenid mussels” to “invasive mussels,” establishes a requirement for CDFW to review and approve updated invasive mussel control plans, and increased the invasive mussel fee.

AB 1150 (Committee on Water, Parks, and Wildlife), Chapter 831, Statutes of 2023, among other things, distinguished that the issuance and collection of the quagga and zebra mussel infestation and prevention fee from the biennial registration renewal.

AB 2443 (Williams), Chapter 485, Statutes of 2012, establishes the quagga and zebra mussel infestation prevention program, which required payment of the invasive mussel fee on vessels and permitted the use of the funds for, among other things, a grant program.

AB 1929 (Hall), Chapter 152, Statutes of 2010, determines that a water operator is indemnified from the penalty of possessing and transporting a restricted species, if the water operator is in compliance with an approved control plan.

AB 2065 (Hancock), Chapter 667, Statutes of 2008, requires reservoir managers to undertake certain measure to prevent invasive mussel infestation, in reservoirs in which invasives mussels have not been detected.

AB 1683 (Wolk), Chapter 419, Statutes of 2007, prohibits a person to possess, import, ship, or transport in the state, or place, plant, or cause to be placed or planted in any water within the state, dreissenid mussels, unless authorized by CDFW. Additionally, authorizes the Director of CDFW, or the Director’s designee, to conduct inspections of conveyances (e.g., vehicles and boats), order that the conveyance be drained, dried, or decontaminated, impound or quarantine conveyances, and conduct inspections of waters of the state and facilities that may contain invasive mussels. Further, required water operators to implement measure to avoid dreissenid mussel infestation and develop a control plan upon infestation, among other things.

REGISTERED SUPPORT / OPPOSITION:

Support

Azusa Light and Water
San Gabriel Valley Municipal Water District
San Gabriel Valley Water Association
Three Valleys Municipal Water District
Upper San Gabriel Valley Municipal Water District

Opposition

Solano County Board of Supervisors
Valley Ag Water Coalition

Analysis Prepared by: Stephanie Mitchell / W., P., & W. / (916) 319-2096