Cooper lake hydroelectric upgrade: restoring stream habitat, improving aquatic conditions.

• Author: White, Rindi
• Position: SPECIAL SECTION: Energy & Power

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A nearly $22 million project to restore salmon habitat on the Kenai Peninsula will get underway this summer at Cooper Lake, near Cooper Landing. It's an effort to restore lost stream habitat and improve aquatic conditions linked to the Chugach Electric Association's Cooper Lake Hydroelectric project.

Chugach, with assistance from the state, is paying for the project. The work includes installing a diversion dam at nearby Stetson Creek, routing cool creek water into the lake, and draining off some of the warmer lake water into Cooper Creek, all with the goal of making salmon spawning conditions more ideal.

The work is a condition the Federal Electric Regulatory Commission (FERC) required when it granted Chugach a new fifty-year license for its Cooper Lake hydroelectric project in 2007.

Adding Salmon to the Kenai River

Chugach spokesman Phil Steyer says when the electric utility went through its relicensing process about ten years ago, resource agencies stated they wanted a three- to five-degree increase in water temperature in the lower part of Cooper Creek.

Chugach placed a dam in the original Cooper Creek drainage in the late 1950s, Steyer explains. The water that flows into the creek now is natural seepage along the creek path and water from Stetson Creek, which drains from high in the mountains, he says. In order to warm the water downstream, the cool mountainous Stetson Creek water will be diverted to Cooper Lake and warmer water from the lake will be allowed to spill out into the creek drainage.

"The two things have the net effect of raising the water temperature at the mouth of Cooper Creek," Steyer says.

What will the project mean in terms of habitat restoration? How many new salmon will be swimming in Cooper Creek or other nearby streams as a result of the project?

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Hard to say, Steyer says. Chugach's original license predates statehood.

"Just finding good empirical data from the 1950s is difficult," he says.

A 2004 report on the potential aquatic habitat benefits conducted by engineering firm HDR for Chugach stated Cooper Creek will likely see "a shift in fish population presence and interaction, an increase in total biomass, and an increase in genetic diversity."

The report states that both resident and migratory rainbow trout populations will likely develop in area drainages and coho and chinook salmon will likely more frequently use the area for spawning, and it could spell more...