Energy policy — hydroelectric: Aspen Castle Creek hydroelectric project in conflict with instream flow needs

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From the Aspen Daily News (Curtis Wackerle):

A city-commissioned report from Miller Ecological Consultants of Fort Collins found that that a minimum of 13.3 cubic feet per second of water needs to be in Castle Creek to ensure healthy fish and plant life, although the stream often doesn’t contain much more water than that…

The city plans to divert a maximum of 25 cfs from Castle Creek to run the turbine of the proposed facility, which would be located in a new building under the Castle Creek Bridge on Power Plant Road. After running the turbine, water would be fed back into Castle Creek. The plant could generate up to 5.5 million kilowatt hours of electricity annually. During spring runoff, Castle Creek can peak between 700 and 900 cfs, or even above like it did this year. But by August in an average year, the creek is running back below 100 cfs. Flows hang around 40 cfs for most of the fall. From about December until the runoff starts again in the spring, water levels in the creek are typically below 20 cfs.

If the Castle Creek hydro plant is built, water levels would be pushed to the minimum stream flow level for a few additional weeks at the beginning and end of the low water season before diversions were reduced or stopped altogether. “With the project in place, you’ll get a longer time period in the fall and spring when (low water) conditions occur,” city public works director Phil Overeynder said. “We’ll have conditions for months at a time when there simply isn’t enough water” and the plant will have to be shut down. The city is committed to maintaining a healthy instream flow in Castle Creek, Overeynder said. “We’re not about to back off of that,” he said…

The city has been working with the Colorado Division of Wildlife on the environmental impacts of the hydropower proposal. It is hoping to get a “conduit exemption” from the Federal Energy Regulatory Commission, which would not require a formal environmental impact statement or environmental analysis. City officials insist that this will save time and money, and that there will still be ample environmental review for the conduit exemption and at the state level.

More hydroelectric coverage here and here.

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