Feds to increase height of Stampede Dam north of Truckee | SierraSun.com

Feds to increase height of Stampede Dam north of Truckee

TRUCKEE, Calif. — When construction crews finished building the Stampede Dam in 1970, gas cost $0.36 a gallon and Richard Nixon was president. Much has changed, including what scientists now know about floods.

Beginning in August, crews will return to the dam to begin a project to increasing its height — a process that is expected to take two construction seasons, according to federal Bureau of Reclamation spokesperson Shane Hunt.

The move follows a 2015 internal risk analysis that found the dam's current height may not be enough to withstand overflow from a major flood event.

"As time goes on, you have more information and better methodologies for these types of things; that's why we're constantly assessing all of our facilities," said Hunt.

Hunt wasn't sure how frequently risk assessments are conducted at Stampede Dam, but said dams with a considerable number of people living nearby are checked more frequently.

If the dam were to overflow, bureau documents indicate the impact could cause the Boca Dam, located 6 miles downstream, to fail as well.

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Hunt said if that happened, it could have a major impact on the downstream cities of Reno and Sparks.

The bureau is raising the dam height 11.5 feet, which will, according to its own report, "provide capacity for temporary containment of floodwaters generated by extreme flood events that would threaten dam integrity."

The increase in height allows for an additional storage capacity of 31,867 acre-feet above the existing dam level. There are about 326,000 gallons of water in one acre-foot.

Reservoir levels and flows are not expected to change after the project's completion.

An environmental review of the project completed in 2012 found there would be no significant impact to the human environment.

Crews will also improve Dog Valley Road from Hobart Mills to the Stampede Boat Ramp turnoff as part of the project and construct two small dikes. No road closures are expected for the remainder of 2016.

Starting in April 2017, the eastern section of Dog Valley Road as well as the Emigrant Group Campground will be closed during the summer construction season.

Hunt said that parts of Dog Valley Road would likely remain closed into 2018 as well.

Stampede Dam was initially built between 1966 and 1970. It supposed to be a storage facility for irrigation water, but state officials decided instead to use the reservoir instead to maintain fishery flows in an effort to protect endangered fish species.

Dam details

Located at Stampede Reservoir in Sierra County about a half hour north of Truckee, Stampede Dam is a rolled earth and rock-filled structure that’s 239 feet high and 1,511 feet long.

Its water storage capacity is 226,500 acre-feet, which is reserved by court decree for fishery enhancement, primarily for the spawning of the endangered cui-ui, along the Truckee River downstream from Derby Dam and Pyramid Lake.

The dam also provides flood control, recreation, a reservoir fishery and other fishery improvements on the main Truckee River, Little Truckee River, and Boca Reservoir.

Source: Bureau of Reclamation. Visit on.doi.gov/2aySWVL to learn more