REDDING, Calif. (AP) — Raising Shasta Dam to boost the state's water supply is feasible and economically justified, but could displace businesses and flood the remaining sacred grounds of a Native-American tribe, according to a study by the U.S. Bureau of Reclamation.
The additional storage would provide water for California's rapidly growing population and help alleviate water shortages.
Lake Shasta, at the northern end of the state, is the starting point for the federally run Central Valley Project. The system of 21 reservoirs, canals and aqueducts funnels water to 3.2 million acres of farmland and supplies water to about 2 million Californians.
"The water supply in California was built for 20 million people 50 years ago and now there are 38 million people, so we're going to have to do something to fix the aging infrastructure," Pete Lucero, spokesman for the Bureau of Reclamation, told the San Francisco Chronicle.
An increase of 12.5 feet or 18.5 feet to the existing 602-foot-high dam would provide the best construction cost-to-storage increase ratio, the study concluded. An 18.5 feet increase would increase the storage capacity of Lake Shasta by 14 percent.
A higher dam also would improve hydropower and fish habitat, the study found.
A larger reservoir would be able to store more cold water, which is needed to help salmon that used to migrate to cooler water upstream before the dam blocked their path, according to the U.S. Bureau of Reclamation.
Even with an 18.5 feet raise, the reservoir would only meet part of California's growing water needs, Lucero said.
The Central Valley Project typically delivers about 5 million acre feet of water on an annual basis for use by farms, cities, towns and wildlife. The increased height would provide space for an additional 634,000 acre-feet of water, but the reservoir would fill to full capacity only in good water years, he said.
"This is not going to be the savior for California, it's just going to be one piece of the puzzle," Lucero said.
It would cost $1.07 billion to increase the height of the dam by 18.5 feet — far less than the cost of building a new dam.
Raising the dam also would mean some businesses and resorts would have to move. And it would cause flooding of lake-side religious sites of the Winnemem Wintu tribe, including two sacred rocks involved in coming-of-age rituals.
Nine-tenths of the ancestral land of the Winnemen Wintu was submerged in 1945, when the federal government built the dam downstream of their ceremonial and prayer grounds.
Some 20,000 Winnemen Wintu once lived along the McCloud River. Today, the tribe counts 122 enrolled members.
It would take at least a decade for construction to begin, if a dam raise is approved. Reclamation officials expect to release a draft environmental study in 2014, followed by a public comment period and final draft. If a project is approved, Congress must still vote to fund it.
Shasta Dam on the upper Sacramento River is the second-largest reservoir run by the Bureau of Reclamation in the country. The dam can hold back up to 4.5 million acre-feet of water, but space is reserved for flood control.