Climate change prompts new concerns about Delta tunnels, Sacramento water supply

Matt Weiser in the Sacramento Bee: The Sacramento City Council this week stepped up its critique of a plan to build two giant water diversion tunnels in the Delta, warning that it may harm the city’s ability to access drinking water in the decades ahead.

The Bay Delta Conservation Plan, as the tunnel project is formally known, is being pushed by Gov. Jerry Brown and a contingent of major water suppliers, mostly in Southern California and the San Joaquin Valley. The goal is to improve water delivery to farms and cities south of the Delta and also protect endangered fish.

The $25 billion project centers on construction of two massive tunnels that would divert a portion of the Sacramento River’s flow underneath the Sacramento-San Joaquin Delta, the largest and most important source of fresh water in the state, and deliver that water to existing diversion canals that begin near Tracy.

The city’s concern stems from an analysis in the plan’s preliminary environmental impact report. The analysis indicates that Folsom Reservoir, for all practical purposes, will be drained dry in one out of every 10 years in a matter of decades. The year 2060 was chosen for analysis, but computer models suggest it could happen sooner. Known in water management circles as “dead pool,” the condition means a reservoir is so depleted that water cannot flow from outlets in its dam. Some water may remain in the reservoir, but there is no easy way to get it out. In that situation, Sacramento may have no way to access its water rights in the American River....

The Sacramento skyline, shot by J.smith, Wikimedia Commons, under the Creative Commons Attribution-Share Alike 3.0 Unported license