Fretting Over Spring Flood Risks
As winter winds down in California, leaving behind a gigantic snowpack, the state must now focus on something it hasn’t dealt with in years: controlling all the runoff.
Los Angeles Mayor Eric Garcetti this week declared a state of emergency amid concerns that snowmelt from the eastern flank of the Sierra Nevada could overwhelm the L.A. Aqueduct, potentially flooding communities nearby. The Central Valley is expected to see high river levels for some time as a result of snowmelt feeding tributaries of the Sacramento and San Joaquin rivers.
Water managers are also using extra care with releases from Lake Tahoe and other reservoirs into the Truckee River, which poses a flood risk to Reno and other communities downstream. And in northeastern Nevada, snowmelt into the Humboldt River could cause flooding in Winnemucca and Battle Mountain.
Adding to the risk is a potential for a rapid rise in temperatures, which could accelerate snowmelt. A forecast by the National Weather Service Climate Prediction Center shows increased odds for above-normal temperatures from the Bay Area southward over the next three to four weeks.
San Francisco Offers Alternative Plan for More River Flows
The city of San Francisco recently offered its own proposal to improve water flows in the San Joaquin River.
It comes in response to a process begun by the State Water Resources Control Board that could require many water users to give up part of their water rights to improve aquatic habitat and water quality in the Sacramento-San Joaquin Delta.
Rather than lose water rights, San Francisco proposes to dedicate certain flows to the ecological needs of fish. The city and other agencies would also spend millions on aquatic habitat improvements.
San Francisco is key to the process because it controls a lot of water in its Hetch Hetchy water system on the Tuolumne River, a tributary of the San Joaquin. It also has close ties with several agricultural irrigation districts downstream. And, indeed, those agencies have already expressed support for the city’s plan.
State officials hoped for this sort of outcome, because it avoids a long, costly process to amend hundreds of water rights. Time will tell if the proposal measures up.
At Last, a Plan to ‘Save’ the Salton Sea
California officials last week unveiled a $383 million plan to protect the Salton Sea and its wildlife from shrinking water levels. Decades in the works, it has become critical to stretching Colorado River supplies among several states as flows diminish.
The giant desert lake, created by an accidental levee break in 1905, became vital to migratory birds after other wetlands were lost to development across the state. The lake is sustained by farm runoff from the Imperial Irrigation District, which has been reduced by water transfers to San Diego and other urban areas. This causes the sea to shrink, eliminating habitat and exposing the lakebed to dust storms that harm air quality.
Officially called the Salton Sea Management Program, it proposes building shallow ponds across thousands of acres on the lake’s north and south shores to maintain habitat and contain dust. Critics say it’s only a drop in the bucket for what the Salton Sea needs and note that the plan does not identify a dependable funding source.
Nevertheless, the plan is an important start. The Imperial Irrigation District, as the largest user of Colorado River water, will likely be required to give up more of that supply to help California reach a deal with Arizona and Nevada over the river’s future. The restoration plan helps ensure that the Salton Sea will be protected if irrigation runoff declines further.
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