Atmospheric rivers: research: forecasting methods: experimental tools.

Removed line-number annotations and duplicated text that were artifacts of the Senate amendment process, producing clean final text.

Added enrolled bill formatting: Senate passage date (May 29, 2025), Assembly passage date (August 19, 2026), signature blocks for the Secretary of the Senate, Chief Clerk of the Assembly, and Governor receipt line.

In finding (j), removed the phrase 'but investment needs range from $2 to $4.5 billion, inclusive, annually for the next 25 years' which had been duplicated from finding (k) due to amendment markup overlap.

In finding (k), removed the word 'only' before 'more than $4.5 billion in state funding has become available,' which was a leftover from the amendment process that altered the meaning of the statement.

In Section 347(b)(2), changed 'shall utilize use all relevant information' to 'shall use all relevant information,' removing a duplicated verb left over from the amendment markup.

The entire provision amending Water Code Section 1242.1 was deleted. This had allowed local or regional agencies to divert floodflows for groundwater recharge without an appropriative water right if conditions were met, including: public notice of imminent flooding, use of existing infrastructure or temporary pumps only (no new permanent construction), protective screens on pump intakes, reporting requirements to the State Water Resources Control Board and groundwater sustainability agencies, and a sunset date of January 1, 2029.

The bill title changed from 'relating to groundwater. atmospheric rivers.' to 'relating to atmospheric rivers,' reflecting the removal of the groundwater component.

The fiscal committee vote requirement changed from 'no' to 'yes,' meaning the bill now requires approval by the Senate Fiscal Committee before advancing, which adds a layer of budgetary review.

Finding (k) was substantially revised: previously stated only $4.5 billion had been allocated to new flood infrastructure since 2006; now states more than $4.5 billion in state funding has become available from bonds and recent budget surpluses, but investment needs range from $50 billion to $115 billion total (approximately $2 billion to $4.5 billion annually for 25 years).

A new finding (q) was added stating that with minimal investment in tools that help predict seasonal and subseasonal atmospheric river forecasts, California can save billions of dollars in flood damages through advanced warning, effective local planning, and effective emergency management.

Finding (n) was revised to add language emphasizing it is 'critical that the Legislature specifically recognize the use of these experimental tools as a key part of the solution to improving predictions about atmospheric river patterns.'

In Water Code Section 347(b)(2), 'shall utilize' was changed to 'shall use' - a nonsubstantive wording change.

Added a new Section 1 containing 17 legislative findings (subdivisions a through q) documenting the severity of atmospheric river impacts in California, including that they cause up to half of annual precipitation and 94 percent of flood damages (~$620M/year), that the Dec 2022-Jan 2023 storms caused over $30B in damage and 20 deaths across 40 counties, that $900B in structures are at flood risk, and that a major flood event could displace 1.5 million people with over $1 trillion in damages.

Bill title changed from 'relating to groundwater' to 'relating to groundwater. atmospheric rivers,' reflecting the expanded subject matter.

Added a new Section 2 amending Water Code Section 347 to establish the AR/FIRO Program in the Department of Water Resources, requiring DWR to research, develop, and implement novel forecasting methods including experimental tools that produce seasonal (1-6 months) and subseasonal (2-6 weeks) atmospheric river forecasts, tailored decision support systems, and use the resulting information to operate reservoirs for flood protection and water capture.

Added definitions of 'seasonal forecast' (approximately one to six months into the future) and 'subseasonal forecast' (approximately two to six weeks into the future) in the new Section 347.

Legislative findings note that California spends $1.8 billion annually on flood control operations and maintenance and $1 billion on new investments, but investment needs range from $2 to $4.5 billion annually for the next 25 years, and only $4.5 billion has been allocated to new flood infrastructure since 2006.

Fiscal committee determination changed from 'no' to 'yes,' indicating the amended bill now has fiscal implications due to the new program requirements on DWR.

In the retained groundwater recharge provision (now Section 3), subdivision (e)(3) was reordered from 'No new permanent infrastructure construction or permanent construction' to 'No new permanent construction or permanent infrastructure.' This is a nonsubstantive wording change.