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Interstate Water Management Committee Meeting Summary: October 13, 2022– Presentation by John Leahigh, CA State Water Project

Link to Meeting Recording: https://youtu.be/jTaNC9O2Ceo

  1. Call to Order – Drew Dehoff, SRBC; Chair
  2. Introductions of participants – Drew Dehoff – SRBC and Interstate Water Management Committee Chair, Beth Callaway — ICWP Executive Director, John Leahigh — CA State Water Project and guest presenter; Adel Abdallah, Anna Normand, Becca Emery, Bennett Bearden, Diego Davis, Erin Spry, Joy Loughry, Julie Westerlund, Laura St. Pierre, Luke Wang, Peter Evans, Wade Loseman, Adam Feihoefer, Christopher Estes, Edward Swaim, Luke Wang, Wei Han.
  3. Transbasin Diversion Webinar Series Presentation: “California State Water Project – Past, Present, and Future”, John Leahigh, P.E., Assistant Division Manager – Water Management, California State Water Project

The presentation began with an overview for why there is a need for the State Water Project. Population centers in the southern and central part of the state are located outside of where most of the precipitation and snowpack occurs. The purpose of the project is to rectify the geographic imbalance of water supply and demand.

There are a number of reservoirs that make up the temporal mismatch between supply and demand. Southern California gets 30% of the CA State Project, 30% CO River, and 30% local supplies (including LA aqueduct that takes water off the backside of the Sierra Nevada). The yield of the project is between 2-2.5MAF. Only in the wettest of years can they deliver close to the 4MAF originally set out.

In 1933 the Central Valley Project Act authorized construction of what is today the Central Valley Project. Today’s State Water Project has 29 water contractors, there are 750k acres of crops served by the water and at least ⅔ of the State’s population (27 million) receives their water from the project.

To power water conveyance, there are significant hydropower releases upstream until they reach sea level at the Bay Delta estuary. Pumping occurs to get the water out of the delta to convey to the Central Valley, then there is significant lift over the coastal range for Central Coast service. It takes 2,000 vertical feet of pumping to then convey the water over the Tehachapi Range into the LA Basin. Highlighted the Lake Oroville dam failure in 2017 that took over $1B to reconstruct. The reservoir holds 3.5MAF of water. It is the tallest dam in the US.

Present challenges include variable hydrology and Delta constraints. Regulatory challenges include environmental limitations due to the hydrodynamic system in the Bay Delta estuary; state water right conditions for water control plans; Endangered Species Act. Future challenges include increasing extreme events (inter and intra-annual); decreasing hydrology supply and increasing evaporative losses. The governor recently adopted a water supply strategy aimed at closing the evaporative gap. Looking at improving storage project investments (that would not be constructed until early 2030s).

  1. ICWP 2022 Annual Meeting – Oct. 25-27th @ Davenport, IA
  2. Other committee topics
    1. Compact case studies
    2. More ideas?
  1. Set next meeting — TBD until after the annual meeting
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