Bill Text: CA AB2521 | 2025-2026 | Regular Session | Amended

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Bill Title: California Council on Science and Technology: water availability study: Central Valley.

Sponsorship: Partisan Bill (Democrat 1)

Status: (Engrossed) 2026-05-28 - In Senate. Read first time. To Com. on RLS. for assignment. [AB2521 Detail]

Download: California-2025-AB2521-Amended.html

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Amended  IN  Assembly  April 15, 2026

Amended  IN  Assembly  March 19, 2026

CALIFORNIA LEGISLATURE— 2025–2026 REGULAR SESSION

Assembly Bill

No. 2521

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Introduced by Assembly Member Papan

February 20, 2026

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An act to amend Section 10721 of add Section 1259.7 to the Water Code, relating to groundwater. water.

LEGISLATIVE COUNSEL'S DIGEST

AB 2521, as amended, Papan. Sustainable groundwater management. California Council on Science and Technology: water availability study: Central Valley.

Existing law establishes the Department of Water Resources within the Natural Resources Agency and vests it with various powers and duties related to water. Existing law requires the State Water Resources Control Board to administer a water rights program pursuant to which the board grants and revokes permits and licenses to appropriate water. Existing law authorizes any person who has an urgent need to divert and use water to apply for, and authorizes the board to issue, a conditional, temporary permit, as prescribed.

Existing law finds and declares that the California Council on Science and Technology (CCST) was organized as a nonprofit corporation at the request of the Legislature for the specific purpose of offering expert advice to the state government on public policy issues significantly related to science and technology.

This bill would, on or before January 1, 2028, require the Department of Water Resources, in consultation with the State Water Resources Control Board and the Department of Fish and Wildlife, to select 2 watersheds that are within, or drain into, the Central Valley to conduct a watershedwide water availability study. The bill would, subject to an appropriation by the Legislature, request CCST to, in consultation with the Department of Water Resources and the board, undertake and complete a comprehensive study of water availability in the selected watersheds. The bill would require the study to, among other things, determine daily flow rates in rivers, streams, and creeks in the watersheds over the past 30 years to the extent data is available. The bill would state the intent of the Legislature for the water availability study to serve as the water availability analysis for future applications to the board for standard or temporary permits for diversion of water to underground storage in the selected watersheds.

This bill would make legislative findings and declarations as to the necessity of a special statute for the Central Valley.

Existing law, the Sustainable Groundwater Management Act, requires all groundwater basins designated as high- or medium-priority basins by the Department of Water Resources to be managed under a groundwater sustainability plan or coordinated groundwater sustainability plans, except as specified. Existing law defines various terms for purposes of the act.

This bill would add the defined term “best available science” for purposes of the act.

Digest Key

Vote: MAJORITY   Appropriation: NO   Fiscal Committee: NOYES   Local Program: NO  

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Bill Text

The people of the State of California do enact as follows:

SECTION 1.

 Section 1259.7 is added to the Water Code, immediately following Section 1259.6, to read:

1259.7.

 (a) The department, in consultation with the board and the Department of Fish and Wildlife, shall select, on or before January 1, 2028, two watersheds that are within, or drain into, the Central Valley to conduct a watershedwide water availability study.

(b) The Legislature requests that the California Council on Science and Technology, in consultation with the department and the board, subject to an appropriation by the Legislature for this purpose, undertake and complete a comprehensive study of water availability in the watersheds selected pursuant to subdivision (a). The study shall accomplish, but is not limited to, all of the following:

(1) Determine daily flow rates in rivers, streams, and creeks in the watersheds over the past 30 years to the extent data is available.

(2) Quantify the maximum allowable diversions under existing permits, licenses, and claims in the watersheds.

(3) Quantify water actually diverted under existing permits, licenses, and claims in the watersheds over the past 30 years to the extent data is available.

(4) Identify and quantify any water quality or environmental flow requirements, including water quality requirements under licenses from the Federal Energy Regulatory Commission, in rivers, streams, and creeks in the watersheds.

(5) Determine when and under what conditions water is available in excess of existing claims and regulatory requirements.

(c) It is the intent of the Legislature that the study completed pursuant to this section will serve as the water availability analysis for future applications to the board for standard or temporary permits for diversion of water to underground storage in the watersheds selected pursuant to subdivision (a).

SEC. 2.

 The Legislature finds and declares that a special statute is necessary and that a general statute cannot be made applicable within the meaning of Section 16 of Article IV of the California Constitution because of the necessity for more groundwater recharge in the Central Valley to increase water supplies, protect communities from flooding, halt land subsidence that damages infrastructure, and prepare California for the next drought.

SECTION 1.Section 10721 of the Water Code is amended to read:

10721.

Unless the context otherwise requires, the following definitions govern the construction of this part:

(a)“Adjudication action” means an action filed in the superior or federal district court to determine the rights to extract groundwater from a basin or store water within a basin, including, but not limited to, actions to quiet title respecting rights to extract or store groundwater or an action brought to impose a physical solution on a basin.

(b)“Basin” means a groundwater basin or subbasin identified and defined in Bulletin 118 or as modified pursuant to Chapter 3 (commencing with Section 10722).

(c)“Best available science” means the use of sufficient and credible information and data, specific to the decision being made and the timeframe available for making that decision, that is consistent with scientific and engineering professional standards of practice.

(d)“Bulletin 118” means the department’s report entitled “California’s Groundwater: Bulletin 118” updated in 2003, as it may be subsequently updated or revised in accordance with Section 12924.

(e)“Coordination agreement” means a legal agreement adopted between two or more groundwater sustainability agencies that provides the basis for coordinating multiple agencies or groundwater sustainability plans within a basin pursuant to this part.

(f)“De minimis extractor” means a person who extracts, for domestic purposes, two acre-feet or less per year.

(g)“Governing body” means the legislative body of a groundwater sustainability agency.

(h)“Groundwater” means water beneath the surface of the earth within the zone below the water table in which the soil is completely saturated with water, but does not include water that flows in known and definite channels unless included pursuant to Section 10722.5.

(i)“Groundwater extraction facility” means a device or method for extracting groundwater from within a basin.

(j)“Groundwater recharge” or “recharge” means the augmentation of groundwater, by natural or artificial means.

(k)“Groundwater sustainability agency” means one or more local agencies that implement the provisions of this part. For purposes of imposing fees pursuant to Chapter 8 (commencing with Section 10730) or taking action to enforce a groundwater sustainability plan, “groundwater sustainability agency” also means each local agency comprising the groundwater sustainability agency if the plan authorizes separate agency action.

(l)“Groundwater sustainability plan” or “plan” means a plan of a groundwater sustainability agency proposed or adopted pursuant to this part.

(m)“Groundwater sustainability program” means a coordinated and ongoing activity undertaken to benefit a basin, pursuant to a groundwater sustainability plan.

(n)“In-lieu use” means the use of surface water by persons that could otherwise extract groundwater in order to leave groundwater in the basin.

(o)“Local agency” means a local public agency that has water supply, water management, or land use responsibilities within a groundwater basin.

(p)“Operator” means a person operating a groundwater extraction facility. The owner of a groundwater extraction facility shall be conclusively presumed to be the operator unless a satisfactory showing is made to the governing body of the groundwater sustainability agency that the groundwater extraction facility actually is operated by some other person.

(q)“Owner” means a person owning a groundwater extraction facility or an interest in a groundwater extraction facility other than a lien to secure the payment of a debt or other obligation.

(r)“Personal information” has the same meaning as defined in Section 1798.3 of the Civil Code.

(s)“Planning and implementation horizon” means a 50-year time period over which a groundwater sustainability agency determines that plans and measures will be implemented in a basin to ensure that the basin is operated within its sustainable yield.

(t)“Public water system” has the same meaning as defined in Section 116275 of the Health and Safety Code.

(u)“Recharge area” means the area that supplies water to an aquifer in a groundwater basin.

(v)“Sustainability goal” means the existence and implementation of one or more groundwater sustainability plans that achieve sustainable groundwater management by identifying and causing the implementation of measures targeted to ensure that the applicable basin is operated within its sustainable yield.

(w)“Sustainable groundwater management” means the management and use of groundwater in a manner that can be maintained during the planning and implementation horizon without causing undesirable results.

(x)“Sustainable yield” means the maximum quantity of water, calculated over a base period representative of long-term conditions in the basin and including any temporary surplus, that can be withdrawn annually from a groundwater supply without causing an undesirable result.

(y)“Undesirable result” means one or more of the following effects caused by groundwater conditions occurring throughout the basin:

(1)Chronic lowering of groundwater levels indicating a significant and unreasonable depletion of supply if continued over the planning and implementation horizon. Overdraft during a period of drought is not sufficient to establish a chronic lowering of groundwater levels if extractions and groundwater recharge are managed as necessary to ensure that reductions in groundwater levels or storage during a period of drought are offset by increases in groundwater levels or storage during other periods.

(2)Significant and unreasonable reduction of groundwater storage.

(3)Significant and unreasonable seawater intrusion.

(4)Significant and unreasonable degraded water quality, including the migration of contaminant plumes that impair water supplies.

(5)Significant and unreasonable land subsidence that substantially interferes with surface land uses.

(6)Depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.

(z)“Water budget” means an accounting of the total groundwater and surface water entering and leaving a basin including the changes in the amount of water stored.

(aa)“Watermaster” means a watermaster appointed by a court or pursuant to other law.

(ab)“Water year” means the period from October 1 through the following September 30, inclusive.

(ac)“Wellhead protection area” means the surface and subsurface area surrounding a water well or well field that supplies a public water system through which contaminants are reasonably likely to migrate toward the water well or well field.