The Brown administration has been pushing forward with the Bay Delta Conservation Plan, a process which is supposed to plan for the impacts of climate change on the Sacramento-San Joaquin Delta and ensure a more reliable water supply for Southern California. Sierra Club California continues to be concerned that the centerpiece of the Bay Delta Conservation Plan is a giant 9,000-cubic-foot-per-second tunnel under the Delta, capable of diverting almost 2/3 of the average flow of the Sacramento River.
Such a large facility makes little sense. To save native fish species, we need to reduce exports from the Delta. If climate change reduces the amount of water available for export, Brown’s plan might not even do much to increase reliability of water supplies for Southern California.
Permanent water scarcity
This past year saw record droughts in the Great Plains and Southwest, extending into the central Sierra Nevada, which saw 60% of normal precipitation. Runoff was down in the San Joaquin River watershed, and farmers using water from Friant Dam for irrigation received half their normal water allocation.
Many scientists link the extent and severity of these droughts to climate change. Global climate models have projected an increase in the frequency and severity of droughts in North America, particularly in the mid-continent and Southwest. The central Sierra Nevada and inland Southern California are on the edge of the drought area. Several models project that drying has started in the central Sierra and will extend to the northern Sierra by the end of the century.
More frequent and severe droughts in the Sierra Nevada would greatly impact not only the Sierran forests but also California’s major rivers and the Delta, already under severe stress from water diversions.
Although the northern Sierra had normal rainfall last year, there were high levels of diversions from the Sacramento River, and high levels of exports of water south from the Delta. As a result, populations of Delta smelt and longfin smelt, which had rebounded during the wet year of 2011, returned to the critically low levels seen during 2000 – 2010.
Over the past decade the Delta ecosystem has entered a “regime change”, characterized by a crash in populations of native species, toxic algal blooms, and expansion of many non-native species. Most scientists believe that the only way to save the estuary is to restore more natural flows, but large wholesale water agencies in the San Joaquin Valley and Southern California, dependent on water exported from the Delta, resist such changes. Climate change will likely make these conflicts worse.
The Sierra Club continues to advocate for increasing reliability of water supplies by reducing reliance on the Delta, increasing conservation, and developing alternative local water supplies, including stormwater capture and water recycling.
From March 14 to April 22 the California Natural Resources Agency is releasing new draft documents of the revised Bay Delta Conservation Plan, with monthly public meetings. The Club’s California/Nevada Water Committee is reviewing the revised plan and preparing a formal comment letter. To get involved with this important effort, please contact committee chair Eric Parfrey at (209)462-7079 or firstname.lastname@example.org.
Deirdre Des Jardins, California water research, Sierra Club California/Nevada Water Committee
To get involved with the Bay Chapter Water Committee, see article.