BILL ANALYSIS                                                                                                                                                                                                    

          |SENATE RULES COMMITTEE            |                        SB 758|
          |Office of Senate Floor Analyses   |                              |
          |(916) 651-1520    Fax: (916)      |                              |
          |327-4478                          |                              |

                                   THIRD READING 

          Bill No:  SB 758
          Author:   Block (D)
          Amended:  6/2/15  
          Vote:     21  

           SENATE NATURAL RES. & WATER COMMITTEE:  8-0, 4/28/15
           AYES:  Pavley, Stone, Allen, Hertzberg, Hueso, Jackson,  
            Monning, Wolk
           NO VOTE RECORDED:  Vidak

           AYES:  Lara, Bates, Beall, Hill, Leyva, Mendoza, Nielsen

           SUBJECT:   Atmospheric Rivers Research and Mitigation  
                     ProgramAtmospheric Rivers Research and Mitigation  

          SOURCE:    Author

          DIGEST:  This bill requires the Department of Water Resources  
          (DWR) to research the cause and effects of atmospheric rivers  
          and to take all actions to capture water generated by  
          atmospheric rivers.

          ANALYSIS:  Existing law establishes DWR to manage the state's  
          water resources. Within DWR is the Hydrology and Flood  
          Operations Office that is responsible for directing DWR's flood  
          and water supply forecasting operations, hydrology and  
          climatology studies, emergency flood operations, and flood  
          control project inspections and encroachment permitting.  The  


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          Office also includes the California State Climatologist.

          This bill:

          1)Establishes the Atmospheric Rivers and Research and Mitigation  

          2)Requires DWR, upon appropriation of special fund moneys,  
            including private funds, to study the causes and effects of  
            atmospheric rivers. 

          3)Requires DWR to take actions, including through reservoir  
            management, to increase water supply and reliability of water  
            resources by capturing water generated by atmospheric rivers.


          What are atmospheric rivers? According to the National Oceanic  
          and Atmospheric Administration, atmospheric rivers are  
          relatively narrow regions in the atmosphere that are responsible  
          for most of the horizontal transport of water vapor outside of  
          the tropics. On the west coast, 30-50% of the annual  
          precipitation on average comes from a few atmospheric river  

          Current operation of flood control dams.  When dams are built  
          for flood control, a flood operations curve is developed to  
          govern flood operations throughout the year. Also known as "rule  
          curves," these curves define how full a reservoir can be for  
          each day of the year, versus how much space must be reserved for  
          potential flood flows.  Rule curves are determined based on an  
          analysis of historic weather and runoff patterns and the  
          potential economic loss due to flooding.

          Because most of California's dams were built in the mid-1900s,  
          the historical record used to create rule curves includes only  


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          the first half of the 20th century.  While our knowledge of and  
          ability to forecast weather has improved, and land use patterns  
          have changed significantly since the initial rule curves were  
          calculated, the rule curves have not typically been updated.   
          Indeed, one common complaint about rule curves is that they do  
          not take into consideration weather forecasts.

          FISCAL EFFECT:   Appropriation:    No          Fiscal  
          Com.:YesLocal:   No

          According to the Senate Appropriations Committee:

        One-time costs of $2.5 million to unspecified special funds and  
            private funds to DWR to expand its extreme precipitation  

        Ongoing costs of $1.25 million to unspecified special funds and  
            private funds to operate and analyze the expanded extreme  
            precipitation network. 

        One-time costs of $500,000 to unspecified special funds and  
            private funds to DWR for a study to improve predictability of  
            the formation and strength of atmospheric rivers.

          SUPPORT:   (Verified5/29/15)

          Bay Area Flood Protection Agencies Association
          Orange County Water District
          Sonoma County Water Agency

          OPPOSITION:   (Verified5/29/15)

          None received


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          ARGUMENTS IN SUPPORT:     According to the author, "California  
          has the most variable precipitation annually of any location in  
          the U.S., ranging from severe drought to major floods.  Research  
          has shown that this variability is largely due to a weather  
          condition known as 'atmospheric rivers' (AR). AR are responsible  
          for 30-50% of California's precipitation and water supply in  
          just a handful of days each year.  Pineapple Express Storms are  
          a common example of AR. Better forecasting of ARs (from hours,  
          to days, weeks and seasons) has the potential to enable new  
          levels of both water supply and flood protection through the use  
          of 'Forecast-Informed Reservoir Operations' (FIRO).  A pilot  
          project to test the feasibility of FIRO is being planned by an  
          expert committee on a vital reservoir on the Russian River, Lake  
          Mendocino. It is led by researchers at the Center for Western  
          Weather and Water Extremes at the University of California San  
          Diego and the Sonoma County Water Agency. This pilot project has  
          the potential to predict AR patterns to make intelligent water  
          management decisions in order to both collect additional water  
          supply and protect against floods. Seasonal AR outlooks are  
          another promising direction that could help water managers and  
          emergency preparedness officials anticipate and prepare for  
          drought and/or flood.  Developing such outlooks is on the  
          cutting edge of science today and SB 758 ensures the state  
          develops a program to study AR."

          Prepared by:Dennis O'Connor / N.R. & W. / (916) 651-4116
          6/2/15 16:00:07

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