Study: Dams could benefit salmon runs in California

SACRAMENTO - California's vast network of reservoirs - which destroyed more than 5,000 miles of salmon habitat when their dams were erected decades ago - could turn out to be a savior for a species on the brink of collapse, according to a new study.

Those dams store cold water, which the study says will be vital to the salmon's survival as climate change is expected to warm California's rivers.

"Paradoxically, the very thing that is constraining fish now, we could use those to our advantage," said study author David Yates, a project scientist at the National Center for Atmospheric Research in Boulder, Colo.

The peer-reviewed paper will appear in a future issue of the Journal of Climatic Change. Yates and the journal agreed to release the study's findings early to The Associated Press.

It comes at a time when the number of salmon returning to spawn in Central Valley rivers, which are crucial to the West Coast stocks, are at historic lows.

Earlier this month, federal fisheries regulators recommended that fishing along California's coast and most of Oregon be suspended for the year. It was the first time the Pacific Fishery Management Council had taken such a drastic step, one that is jeopardizing the $150 million West Coast salmon industry.

Unfavorable ocean conditions, habitat destruction, dam operations, agricultural pollution and climate change are among the potential causes.

Federal authorities declared the West Coast ocean salmon fishery a failure Thursday, a move that opens the way for Congress to appropriate economic disaster assistance for coastal communities in California, Oregon and Washington.

Historically, 1 million to 3 million chinook salmon spawned annually in the streams that tumbled out of the western Sierra Nevada. This year, just 50,000 are expected to return to the Central Valley river systems.

Yates' research projects that an increase in air temperature of 3.6 degrees to 7.2 degrees Fahrenheit could be lethal for the young winter-run and spring-run salmon in the Sacramento River. The increase in water temperatures would vary depending on the depth and flows of the river.

Studies have shown that high water temperatures have wide-ranging and potentially fatal consequences for salmon, which generally need water temperatures lower than 68 degrees when they return to fresh water. It reduces their swimming ability, increases their vulnerability to disease and leads to lower growth rates. Spawning females require even colder water of 57 degrees for their eggs to live and juvenile salmon migrate back to the ocean more successfully when the river is no more than 64 degrees.

Higher water temperatures can be offset if federal water managers preserved the cold water stored behind Shasta Dam, near the head of the Sacramento River, and released it when the salmon head upriver. Salmon that once headed far upstream to cooler, mountain streams are now forced to spawn in valley waters because the dam blocks their path.

It's a management option not available on rivers that aren't dammed.

"Very pristine places are probably more vulnerable to climate change because we don't have the knobs to turn to manage them," Yates said in an interview with the AP.

Releasing cold reservoir water for salmon at certain times of the year would require a shift in strategy regarding how the state's water is apportioned for farmers and some 23 million Californians.

Reassessing how California's water is managed is one of the recommendations to be released Thursday as part of a separate report by the National Wildlife Federation and the California-based Planning and Conservation LeagueThe report, which relies in part on Yates' study, illustrates how California's fish, waterfowl and other species will struggle to survive over the next century as climate change alters their habitat.

"We need to take a step back and look at how we're going to manage water in a more comprehensive manner and save salmon," said Mindy McIntyre, a water specialist at the Planning and Conservation League.

State scientists say climate change could lead to more winter flooding, summer droughts, warmer rivers and streams, and rising seas that will push salt water farther upstream from San Francisco Bay.

Temperature spikes are particularly worrisome for cold water fish such as salmon, steelhead and the state fish, the California golden trout, according to research compiled in the National Wildlife Federation report.

The state and federal governments operate 40 dams and reservoirs that were built primarily between the 1930s and the 1970s to tame California's flood-prone rivers and store spring snowmelt. The reservoirs supply drinking water to about two-thirds of state residents and irrigation water to farmers throughout the Central Valley.

Construction of Friant Dam north of Fresno, for example, wiped out salmon runs on the San Joaquin River.

"Fish are the ones that don't have a voice," said Amanda Staudt, a climate scientist at the National Wildlife Federation. "We're not saying those other uses aren't important, we just need to ensure fish are in the mix."

Farmers and cities that depend on Northern California's water already are grappling with less water than they have been used to in the past.

That's in part because of a federal judge's directive last year that state and federal water managers restrict pumping out of the Sacramento-San Joaquin Delta by as much as 30 percent. The cutback was ordered to protect the threatened delta smelt.

Those pumping restrictions, coupled with last year's drought and dry conditions in March and April, have left the state's reservoirs lower than normal. As a result, water deliveries have been reduced significantly.

The cutbacks have increased calls by Central Valley farmers, the Los Angeles Metropolitan Water District and water managers in the San Francisco Bay area to build more dams and consider sending fresh water around the delta by canal or underground pipe.

"We have to rethink this system that was created in the middle of the last century," said Tim Quinn, executive of the Association of California Water Agencies, whose organization has supported building more dams. "It was not designed with fish in mind."

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Read the National Wildlife Federation Report at www.nwf.org