Investing for California’s Future - Groundwater, Not Dams

Shasta Dam in California

California has already used up the best locations for surface storage

  • We have more than 1,400 dams in the state, fuelling 1,300 reservoirs.  
  • Every major river in California is dammed and some have two or more.  
  • New locations are less and less valuable in terms of water available for storage and in terms of environmental impact.

Dams wreak havoc on the environment

  • In-stream dams block migrating fish, such as salmon, reducing their ability to reproduce.
  • Diversions from rivers and streams to fill off-stream reservoirs reduce flow into the Delta, jeopardizing the most diverse ecosystem on the West Coast of the Americas.
  • Diversions also flood thousands of acres of valuable acreage, including sensitive habitat for endangered or threatened species.

Surface water storage is less sensible than groundwater storage

  • Dams and reservoirs cost six times as much as groundwater storage projects to build.
  • Reservoirs deplete first in a drought, so they’re not the best choice for multi-year droughts like the one we’re going through now.
  • In dry seasons, depending on size, dam reservoirs and diversions can evaporate more water than they store.
  • Dams displace local residents who have lived on their land for generations— worldwide, large dams have forced some 40-80 million people from their lands in the past six decades.  

Funding Groundwater Storage Makes More Sense

  • The state has more than 500 groundwater basins, all of which would benefit from recharge.
  • 21 groundwater basins are in a “critical” condition, according to a recent state report. Critical condition means significantly more water has been taken out than put back in.   
  • A warmer climate will make our reservoirs less useful as they’ll fill up faster and spill over. But we can capture that water as it moves downstream and store it underground, reducing flood risk and restoring our groundwater basins.  
  • In an average water year, groundwater supports about 40 percent of the state’s urban and agricultural water uses.  In drought, our reliance climbs above 60 percent.  

Groundwater Storage is Cheaper than Surface Water

  • $2.7 billion can fund 8.4 million acre-feet of groundwater storage, compared to just 1.4 million acre-feet of storage.
  • Groundwater depletion causes subsidence. Some of the farmland in the San Joaquin Valley sunk 13 inches in 2014 according to a NASA report.  The cost of subsidence in terms of damage to roads, canals and other infrastructure has not been calculated but is likely in the tens of millions.  

Groundwater Storage is More Climate Resilient

  • We will be increasingly reliant on groundwater resources as snowpack continues to shrink and reduces surface water supplies due to warming temperatures.  
  • Groundwater storage is more climate resilient because water stored underground is not as vulnerable to evaporation as surface water.

Read more on our blog: The California Water Commission Needs to Acknowledge the Elephant in the Room

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