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California's Delta and the Future of State-scale Water Supplies

California's Delta and the Future of State-scale Water Supplies. Mike Dettinger USGS/SIO. California's Water Supplies. 75% of runoff occurs in north 72% of consumptive use in south. Sacramento-San Joaquin Delta & Watershed. http://www.water.ca.gov/maps/allprojects.html.

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California's Delta and the Future of State-scale Water Supplies

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  1. California's Delta and the Future of State-scale Water Supplies Mike Dettinger USGS/SIO

  2. California's Water Supplies • 75% of runoff occurs in north • 72% of consumptive use in south Sacramento-San Joaquin Delta &Watershed http://www.water.ca.gov/maps/allprojects.html

  3. Uses of the Major Water Projects Agriculture Urban

  4. Water Sources for Urban Southern California New CR Xfers Delta Metropolitan Water District Urban Water Management Plan, 2005

  5. NORTH San Joaquin R Delta Sacramento R Bay In today's State-scale water-supply system, the Delta is the critical, but weak, link between North & South

  6. The Delta is a 2200 km2 maze of • Farms • Channel & sloughs • Marshlands • Suburban • Encroachment • …all sitting very near sea level with water held in place by aging, poorly engineered levees 50 km

  7. High quality Sacramento River Delta as the North-South Meeting Place of Waters ? Salty seawater Low quality San Joaquin River Water pumped south

  8. The Big Gulp • In the event of several major levee breaches, sea water is expected to flow in and cutoff passage for southbound freshwater flows to the export pumps in the southern Delta (*) • Sea-level rise, increased flood flows, aging levees, earthquakes together offer an estimated 60% chance of this happening by 2050 (Mount & Twiss, 2005) The Big Gulp Florsheim & Dettinger, 2005

  9. ECOSYSTEMS Endangered fisheries, shrinking wetlands& declining landscapes have devastated the once-rich ecosystems of Central California.

  10. Outflows and Diversions from the Delta

  11. Outflows and Diversions from the Delta Slightly over 20 MAF Slightly over 20 MAF

  12. Sources and Fates of Dissolved Organic Carbon in the Delta Luoma et al., 2008 DOM in treated water ends up contaminating with byproducts like THMs (NOT GOOD!)

  13. DRIVERS of DELTA CHANGE Pelagic organism declines (POD) Less reliable water supplies Deteriorating water quality Threats to agriculture, communities & infrastructure corridors • Land subsidence • Invasive species • Population growth & urbanization • Earthquakes • Climate change • Sea level rise

  14. What should the future Delta look like? Mount, Twiss & Adams, 2006

  15. Business as Usual? • Ecosystem's piece of the Pie? • Crumbling Levees & "The Big Gulp"

  16. Fortress Delta? • Astronomical cost! • Sea-Level Rise & Receding Targets • Ecosystems are adapted to variable flows & salinity (not Delta as concrete canal)

  17. Abandoned Delta? • Peripheral Canal ! • (Voters rejected in 1982, but its back!) • Ecosystem or sewer? • 560,000 acres of prime agriculture; $2B (in-Delta) agricultural economy

  18. Restored Delta? • Restored to what? • Sea level rise, invasive species & sediment supply • Would this provide water supply reliability? Infrastructure corridors?

  19. Governor’s Blue Ribbon Delta Visions Panel conclusions (2008): • 3. Dual conveyance: Leaky peripheral canal & variable salinity Delta • 4. Re-governance the Delta • 5. STOP suburbanization! • 6. Armored levees where needed (human life), abandoned levees for ecosystems & over-toppable levees for agriculture • 7. Variable flow regimes & geomorphology • 8. Carbon "farms"? Coequal water supply & ecosystem goals 2. Dual conveyance facilities (instead of BAU or isolated Delta, both!)

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