Dan Walters

December 16, 2013

Dan Walters: More storage may be California’s most important water issue

While California fights over whether to build twin tunnels under the Sacramento-San Joaquin Delta to carry water, a more important issue may be whether the state has enough reservoir capacity to capture winter rains.

The release last week of detailed plans for building water tunnels beneath the Sacramento-San Joaquin Delta touches off a legal and political battle that could take years to resolve.

The tunnels, however, are merely one aspect of securing an adequate and dependable water supply for the state – and perhaps not even the most important aspect.

The tunnels, if built, would allow some Sacramento River water to bypass the environmentally stressed Delta on its way to the head of the California Aqueduct near Tracy.

However, a more fundamental issue is whether there will be enough water, when needed, to satisfy the 25 million Californians who draw water from the aqueduct and farmers, while enhancing the Delta’s deteriorated habitat for fish and other Delta wildlife.

The state’s largest reservoir, by far, is the snowpack that accumulates in the Sierra during winter months and is released into the Sacramento-San Joaquin river systems as warmer spring and summer weather melts the snow.

Under natural circumstances, those flows are seasonal, and as California’s population increased during the 20th century, state, federal and local agencies constructed dozens of dams and reservoirs to capture the melting snow and keep the state’s rivers flowing year-round.

Meteorologists believe that climate change will reduce California’s winter snowfall and increase its rainfall, thus shrinking the natural snowpack reservoir. If that’s true, California will need more man-made storage, either surface reservoirs or underground aquifers, to capture seasonal rainfall.

Federal and state water officials are planning to expand major reservoirs, such as Shasta and San Luis, to gain marginal increases in capacity, but we really need at least 1 to 2 million acre-feet of new storage, even without climate change effects, as the current drought proves.

“Expanding and improving California’s water storage capacity is long overdue,” Sen. Dianne Feinstein wrote recently. “The last time we saw significant state and federal investments in our water storage and delivery system was in the 1960s, when the state’s population stood at 16 million. … If we don’t take significant and rapid action, I fear California is at risk of becoming a desert state.”

Oddly, however, the environmental groups most alarmed about climate change also oppose increasing water storage, such as a new off-stream reservoir called Sites in the upper Sacramento Valley and a new reservoir called Temperance Flat on the San Joaquin River.

Four years ago, the Legislature approved a water bond issue that includes $3 billion for storage projects, but it was never submitted to voters and efforts will be made in 2014 to write a smaller substitute measure.

One of its major conflicts will be over money for storage, and what happens will have a material impact on California’s future.

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