Tuesday, May 11, 2010

Increasing Dam’s Storage

This article from the San Diego Union-Tribune is about the doubling of storage capacity of a local dam by raising it 117 feet from its current 220 feet.

An earlier post, Dams are the Solution, noted the possibility of tripling the storage capacity of Shasta Dam—reported by the Los Angeles Times—if it was raised to its originally engineered height.

An excerpt from the San Diego article.

“EAST COUNTY— Construction crews will soon begin the painstaking work of raising East County’s San Vicente Dam, a project the San Diego County Water Authority calls the largest of its kind in the world.

“The $568 million effort involves boosting the 220-foot-high dam by an additional 117 feet. Work is expected to begin this spring and finish in early 2013. When the dam raise is completed, the capacity of the adjoining San Vicente Reservoir will more than double.

“The project is part of a larger, $1.5 billion effort by the San Diego County Water Authority to provide up to six months of storage in the event of an emergency.”

An excerpt from the Los Angeles article.

“REDDING - From Highway 151, Shasta Dam emerges through the fog and rain like an awesome apparition, a giant wall of concrete whose power generators humming eerily far below add to its supernatural dimension.

“As California looks for new ways to increase water supplies in the face of mounting shortages, this monstrous 602-foot facade holding back the Sacramento River seems destined to grow even taller.

“It's a perfect spot for expansion, although it's not the only site under intense scrutiny in this scramble for new water storage.

“Shasta Dam was designed to be 800 feet tall, so adding concrete to its top presents no significant engineering obstacles.

"This is like adding a room on a house, rather than building a new house," said Michael J. Ryan, the Bureau of Reclamation's Northern California area manager, whose small office overlooks the dam, the lake and, on a clear day, Mount Shasta looming large in the distance.

“But most importantly, the clean, cold water it would add to the state's supply is exactly what water managers are looking for. A taller dam means additional downstream protection against floods, more downstream supply for farms and cities and, because Shasta Lake would be deeper, more cold water to send downriver when the salmon are looking for a place to spawn....

"According to a 1999 Bureau of Reclamation study, a dam 200 feet taller would be able to triple storage to 13.89 million acre-feet of water.

"Still, tripling the size of Shasta Lake, on paper at least, would store nine times the projected 2020 water deficit for the Sacramento, San Joaquin and Tulare Lake basins during normal water years.”