Rivers board: Aspen hydro project could harm streams | AspenTimes.com

Rivers board: Aspen hydro project could harm streams

Janet UrquhartThe Aspen TimesAspen, CO Colorado
Michael Faas/Aspen Times fileCastle Creek flows past the site of a proposed Aspen hydroelectric plant.Pitkin County's Health Rivers and Streams Board has expressed concerns about the impact of the project on the health of both Castle and Maroon creeks.

ASPEN – Pitkin County’s Healthy Rivers and Streams Board has raised concerns about the impact of a proposed Aspen hydroelectric project on the health of two local creeks from which water would be diverted.The board, which met Monday, forwarded a two-page letter to David Hornbacher, the city’s deputy director of utilities and renewable energy, on Friday – the final day the city was accepting comments on its draft application to the Federal Energy Regulatory Commission for the hydro plant.Attached were 58 pages of attachments comprising the analyses of four experts hired by the county rivers board to review the city’s studies of the project. The county spent $50,000 on the review, which involved a Denver water attorney, Boulder engineering consulting firm, an aquatic specialist based in Eagle and a Telluride firm hired to review the expected energy output of the plant.”We have significant concerns about the health and quantity of the waters in Castle and Maroon creeks,” said the board’s letter, signed by Chairman Greg Poschman. “The city’s hydroelectric project represents a potential conflict with the mission of our board.”Among the board’s suggestions: The city should define and preserve a “healthy” streamflow as opposed to merely adhering to minimum streamflows.The board also called on the city to make a legal commitment to maintain stream quality and quantity throughout the year as part of its operation of the hydro plant, and concluded that more complete data is needed over a longer period of time in order to assess the impacts associated with the hydroelectric facility.Aspen is seeking a “conduit exemption” from the Federal Energy Regulatory Commission for its project. Such exemptions, granted for small hydroelectric projects that use infrastructure that is primarily used for other purposes, involve less onerous environmental reviews.The county rivers board, however, has encouraged the city to revisit the appropriateness of the exemption in its application to the commission.Among the experts hired to review the city’s application, water engineering firm AMEC Earth & Environmental urged a more thorough study of the available water on Castle and Maroon creeks during all months of the year and during a range of wet, average and dry years. The monitoring should continue for at least 20 years, the firm’s report said.The firm also urged real-time measurements and publicly accessible reporting of the flows left in the creeks as water is diverted for the hydro plant.Aqautic specialist Greg Espegren’s report questions the impact of drawing down the creeks to minimum flows for extended periods of time during the fall and winter months, as well as the barriers that the diversion structures themselves will create for fish movement.City voters approved $5.5 million in bonds to build the hydro project in 2007. The city’s goal is increasing its use of renewable energy to generate electricity, but critics of the controversial project have called into question its potential impacts on the health of the creeks.The new hydro plant would be constructed along Castle Creek, where a hydropower facility once existed before it was taken out of service in the late 1950s.The city’s plan calls for diverting no more than 25 cubic feet per second from Castle Creek and as much as 27 cfs from Maroon Creek to run the plant’s turbine. Water from both creeks would be diverted to the city’s Thomas Reservoir and then flow down a drain line to the plant, before being returning to Castle Creek. Flows would be reduced along 2.4 miles of Castle Creek and 2.7 miles of Maroon Creek.janet@aspentimes.com

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