AB 2521 California Assembly · 2025-2026 Regular Session

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

Summary

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 require the study to be completed within 2 years of the Legislature appropriating money for purposes of undertaking the study. 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.

Bill status passed 3 of 5 stages cleared

Introduction

Feb 2026

Committee Review

Aug 2026

Assembly Passage

May 2026

Senate Passage

Governor

Introduced Feb 20, 2026 Last action Aug 13, 2026

Maddy AI version diff · 4 comparisons

What changed between versions

03/19/26 - Amended Assembly → 04/15/26 - Amended Assembly · 6 edits · Apr 15, 2026

MODERATE

AB 2521 was substantially restructured between these versions. The San Francisco Bay Conservation and Development Commission membership provisions were removed entirely, and a new section (Water Code 1259.7) was added requiring the Department of Water Resources to select two Central Valley watersheds by January 1, 2028 for a comprehensive water availability study to be conducted by the California Council on Science and Technology. The bill also now includes legislative findings justifying a special statute for the Central Valley focused on groundwater recharge, flood protection, land subsidence, and drought preparedness.

Scope change

The bill's scope expanded significantly. It previously covered only a new 'best available science' definition in the Sustainable Groundwater Management Act plus nonsubstantive Bay Commission membership changes. It now also mandates a major Central Valley water availability study through CCST, adds legislative findings justifying special treatment for the Central Valley, and creates a pathway for that study to inform future underground storage permit applications.

SCOPE

The entire amendment to Government Code Section 66620 (San Francisco Bay Conservation and Development Commission membership) was removed from the bill. These were described as nonsubstantive changes to commission membership.

The bill states legislative intent that the completed study will serve as the water availability analysis for future applications to the State Water Resources Control Board for standard or temporary permits for diversion of water to underground storage in the selected watersheds.

A new Section 2 adds legislative findings and declarations that a special statute is necessary for the Central Valley due to the need for more groundwater recharge to increase water supplies, protect communities from flooding, halt land subsidence that damages infrastructure, and prepare California for the next drought.

REQUIREMENT

New Water Code Section 1259.7 requires the Department of Water Resources, in consultation with the State Water Resources Control Board and the Department of Fish and Wildlife, to select two watersheds within or draining into the Central Valley by January 1, 2028 for a watershedwide water availability study.

The study must determine daily flow rates in rivers, streams, and creeks over the past 30 years; quantify maximum allowable diversions under existing permits, licenses, and claims; quantify water actually diverted over the past 30 years; identify water quality or environmental flow requirements including FERC license requirements; and determine when water is available in excess of existing claims and regulatory requirements.

FISCAL

The bill requests that CCST undertake the water availability study, subject to an appropriation by the Legislature. The fiscal committee designation changed from 'no' to 'yes,' reflecting this new funding requirement.

Floor votes · Assembly May 27, 2026

How they voted

59–9

Passed · 11 other

Total votes 79

May 27, 2026

D Democratic59

57 Yea 2

96% Yea

R Republican20

2 Yea 9 Nay 9

45% Nay

Vote distribution

All Yea All Nay Mixed No data

Full legislative history

Actions timeline

Total actions

Key actions

Committee

Amendments

Aug 13, 2026

Upper · Passed

In committee: Held under submission.

upper

Aug 3, 2026

Committee

In committee: Referred to APPR. suspense file.

upper

Jul 2, 2026

Upper · Passed

Read second time and amended. Re-referred to Com. on APPR.

upper

Jul 1, 2026

Introduced

From committee: Amend, and do pass as amended and re-refer to Com. on APPR. (Ayes 6. Noes 0.) (July 1).

upper

Jun 10, 2026

Committee

Referred to Com. on N.R. & W.

upper

May 27, 2026

Lower · Passed

Read third time. Passed. Ordered to the Senate. (Ayes 60. Noes 9.)

lower

May 14, 2026

Lower · Passed

From committee: Do pass. (Ayes 11. Noes 1.) (May 14).

lower

May 6, 2026

Committee

In committee: Set, first hearing. Referred to APPR. suspense file.

lower

Apr 23, 2026

Lower · Passed

From committee: Do pass and re-refer to Com. on APPR. (Ayes 8. Noes 0.) (April 23). Re-referred to Com. on APPR.

lower

Apr 16, 2026

Committee

Re-referred to Com. on W., P., & W.

lower

Apr 15, 2026

Introduced

From committee chair, with author's amendments: Amend, and re-refer to Com. on W., P., & W. Read second time and amended.

lower

Mar 23, 2026

Committee

Re-referred to Com. on W., P., & W.

lower

Mar 19, 2026

Introduced

From committee chair, with author's amendments: Amend, and re-refer to Com. on W., P., & W. Read second time and amended.

lower

Mar 19, 2026

Committee

Referred to Com. on W., P., & W.

lower

Feb 21, 2026

Lower · Passed

From printer. May be heard in committee March 23.

lower

1 primary · 0 co-sponsors