Delta Water Tunnels Would Do Far More Harm Than Good

Sep 3, 2014
Deb Self
by Deb Self

The proposed 35-mile tunnels to carry fresh water from the northern end of the Sacramento-San Joaquin Delta to pumps on the southern end would harm San Francisco Bay. This $25 billion project would also devastate the Delta ecosystem and wipe out California’s salmon fishery.

Two major rivers, the Sacramento and the San Joaquin, flow into the Delta. The Delta, in turn, provides a vital source of fresh water that flows into San Francisco Bay, keeping the Bay’s mix of salt and fresh water at the right level for fish and other wildlife. The Delta also supplies fresh water to cities and farms.

However, demand for water far outstrips the available supply. Unsustainable amounts of fresh water are already being taken out of the Delta, pushing its fragile and overtaxed ecosystem to the verge of collapse. The tunnels would steal massive amounts of more fresh water and send it to southern California cities and Central Valley agriculture.

Baykeeper and dozens of other environmental groups have opposed the Delta tunnels and similar attempts over the decades to rob the Delta of fresh water. The biggest problem is that taking out more fresh water through the tunnels would draw the Bay’s saltier water into the northern Delta. In addition, with less water flowing through the Delta, its channels would be shallower and slower-moving, so the water would also be much warmer. Under these conditions, according to the Golden Gate Salmon Association, salmon would not be able to spawn. As a result, California’s commercial and sport salmon fishery could be wiped out, along with the estimated $1.5 billion in economic activity it generates each year. Many other fish species would decline in numbers and some would be unable to survive at all, according to the Bay Institute.

Currently, fresh water for cities and agriculture is pumped out of the southern Delta. Tunnel supporters claim that routing more fresh water through the tunnels to the southern Delta will reduce the high number of fish that are now killed by the southern Delta pumps. However, the Bay Institute points out that the pumps would still be operating, and the tunnels themselves would cause as much or more harm to fish.

While the tunnel proposal includes funds for restoring tidal marshes in the Delta and along part of the Sacramento River, the environmental damage caused by the project would far outweigh the benefits. According to the best available science, the Delta and its wildlife would continue to deteriorate if California water agencies remove more fresh water, and without sufficient fresh water, the tidal marsh restorations would fail.

Downstream from the Delta, the tunnels would directly harm San Francisco Bay by changing the Bay’s salt levels. Removing so much fresh water would also remove water-borne sediment that would have flowed downstream to nourish the Bay’s wetlands. The wetlands filter out pollution, provide vital wildlife habitat and help protect the shoreline from sea level rise caused by global climate change. The tunnel project could make efforts to restore wetlands around the Bay more difficult. And without adequate sediment to help marshes grow and migrate as sea levels rise, existing Bay wetlands could disappear. 

The $7.5 billion water bond slated for the November election has been described as “tunnel neutral,” despite some funds that could be applied to the proposed tunnel project. In polls, the California public has shown a staunch opposition to the building of destructive water tunnels to siphon off the Delta’s fresh water. The public should stay alert for opportunities to weigh in again.

There are far better solutions to California’s chronic water shortage. Certainly, we should all be mindful of our own water use and our cities should fix their aging networks of leaky water supply pipes. But with agriculture using more than 80 percent of California’s water, new agricultural water conservation measures would make the biggest difference, according to the Pacific Institute. In its 2008 study of Delta water use, the nonprofit found that changes to irrigation management would free up millions of acre-feet of water every year, without harming the agriculture sector economically. To save the Delta and protect the health of San Francisco Bay, California needs to forget about taking more fresh water out of the Delta. As we face the challenge of climate change, let’s focus instead on water conservation.

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