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SB-599 • 2026

Atmospheric rivers: research: forecasting methods: experimental tools.

Atmospheric rivers: research: forecasting methods: experimental tools.

Passed Legislature

This bill passed both chambers and reached final enrollment, even if later executive action is not shown here.

Sponsor
Caballero
Last action
2025-09-10
Official status
Ordered to inactive file on request of Assembly Member Aguiar-Curry.
Effective date
Not listed

Plain English Breakdown

The official source material does not provide specific details on how the department will research new prediction methods, only that experimental tools for seasonal forecasts are required.

Atmospheric Rivers: Research and Forecasting

This law requires the Department of Water Resources to use experimental tools for better forecasting of atmospheric rivers over longer periods, such as seasons or months ahead.

What This Bill Does

  • Establishes a program called AR/FIRO in the Department of Water Resources to study and improve forecasts about atmospheric rivers.
  • Requires the department to research new ways to predict when and where atmospheric rivers will happen.
  • Makes sure that experimental tools are used for forecasting atmospheric rivers over longer periods, like seasons or months ahead.

Who It Names or Affects

  • The Department of Water Resources
  • People who rely on water supply forecasts

Terms To Know

Atmospheric Rivers
Large air currents that carry a lot of moisture and can cause heavy rain or snow.
Forecast-Informed Reservoir Operations (FIRO)
Using weather forecasts to manage water in reservoirs better.

Limits and Unknowns

  • The bill does not specify how much money will be used for this research.
  • It is unclear when the experimental tools will start being used.

Bill History

  1. 2025-09-10 California Legislative Information

    Ordered to inactive file on request of Assembly Member Aguiar-Curry.

  2. 2025-09-02 California Legislative Information

    Read second time. Ordered to third reading.

  3. 2025-08-29 California Legislative Information

    From committee: Do pass. (Ayes 15. Noes 0.) (August 29).

  4. 2025-07-16 California Legislative Information

    July 16 set for first hearing. Placed on APPR. suspense file.

  5. 2025-07-01 California Legislative Information

    From committee: Do pass and re-refer to Com. on APPR. with recommendation: To consent calendar. (Ayes 12. Noes 0.) (July 1). Re-referred to Com. on APPR.

  6. 2025-06-05 California Legislative Information

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

  7. 2025-05-29 California Legislative Information

    In Assembly. Read first time. Held at Desk.

  8. 2025-05-29 California Legislative Information

    Read third time. Passed. (Ayes 38. Noes 0. Page 1328.) Ordered to the Assembly.

  9. 2025-05-27 California Legislative Information

    Ordered to special consent calendar.

  10. 2025-05-23 California Legislative Information

    Read second time. Ordered to third reading.

  11. 2025-05-23 California Legislative Information

    From committee: Do pass. (Ayes 6. Noes 0. Page 1206.) (May 23).

  12. 2025-05-16 California Legislative Information

    Set for hearing May 23.

  13. 2025-05-05 California Legislative Information

    May 5 hearing: Placed on APPR. suspense file.

  14. 2025-04-29 California Legislative Information

    Set for hearing May 5.

  15. 2025-04-24 California Legislative Information

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

  16. 2025-04-23 California Legislative Information

    From committee: Do pass as amended and re-refer to Com. on APPR. with recommendation: To consent calendar. (Ayes 6. Noes 0. Page 839.) (April 22).

  17. 2025-04-04 California Legislative Information

    Set for hearing April 22.

  18. 2025-04-02 California Legislative Information

    Re-referred to Com. on N.R. & W.

  19. 2025-03-24 California Legislative Information

    From committee with author's amendments. Read second time and amended. Re-referred to Com. on RLS.

  20. 2025-03-05 California Legislative Information

    Referred to Com. on RLS.

  21. 2025-02-21 California Legislative Information

    From printer. May be acted upon on or after March 23.

  22. 2025-02-20 California Legislative Information

    Introduced. Read first time. To Com. on RLS. for assignment. To print.

Official Summary Text

SB 599, as amended, Caballero.
Atmospheric rivers: research: forecasting methods: experimental tools.
Existing law establishes the Atmospheric Rivers Research and Forecast Improvement Program: Enabling Climate Adaptation Through Forecast-Informed Reservoir Operations and Hazard Resiliency (AR/FIRO) Program in the Department of Water Resources. Existing law requires the department to operate reservoirs in a manner that improves flood protection, and to reoperate flood control and water storage facilities to capture water generated by atmospheric rivers. Existing law requires the department to research, develop, and implement new observations, prediction models, novel forecasting methods, and tailored decision support systems to improve predictions of atmospheric rivers and their impacts on water supply, flooding, post-wildfire debris flows, and environmental conditions.
This bill would, for novel forecasting methods researched, developed, and
implemented by the department, require the department to include the use of experimental tools that produce seasonal and subseasonal atmospheric river forecasts, as defined.

Current Bill Text

Read the full stored bill text 
Download Bill PDF