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Aspen pumps up effort for hydropower

Rustin Gudim/The Aspen TimesAn aquatic biology study will be conducted to determine what the effects would be if the city diverts water from Castle Creek to power a new hydroelectric plant in Aspen.
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Carolyn Sackariason

The Aspen Times

Aspen, CO Colorado



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An aquatic biology study will be conducted to determine what the effects would be if the city diverts water from Castle Creek to power a new hydroelectric plant in Aspen.

An aquatic biology study will be conducted to determine what the effects would be if the city diverts water from Castle Creek to power a new hydroelectric plant in Aspen.ENLARGE

ASPEN – The Castle Creek hydroelectric power plant continues to move forward with the latest $2.3 million expenditure approved by the Aspen City Council last week.



The council approved a contract with Denver-based Western Summit Constructors to build a pipeline that will deliver water from Castle Creek via the Thomas Reservoir to the plant, which will be located below the Castle Creek bridge.

The city plans to circumvent a full-blown environmental analysis and instead apply to the Federal Energy Regulatory Commission (FERC) for what’s called a “conduit exemption” to build the hydroelectric plant once the pipeline is under construction.

Officials say by delivering water from the reservoir to the plant, the city can take advantage of water for hydropower while providing needed flood protection to properties downhill of the Thomas Reservoir, such as the hospital.

The council also approved a $48,400 contract with Miller Ecological Associates to conduct an aquatic biology study to determine the effects of taking water from the creek. The study was requested by the Colorado Division of Wildlife to evaluate the effect of stream-flow changes between the point of diversion and the point of return in the creek.

The result of the study may mean more water will be available for in-stream flows, rather than for creating electricity.

Last fall, the city held a public meeting, and several individuals who live in the Castle Creek Valley and hold water rights in the creek called for a full environmental impact statement (EIS) to be done before the project is completed.

That analysis would address whether the city’s environmental goal to create hydropower comes at the expense of the streams, wildlife and individuals who own water rights.

Several people said they were concerned about a decreased flow in Castle and Maroon creeks because water will be drained out of both to generate power. Under an agreement with the state, the city of Aspen would never go below 12 cfs in Castle Creek and 14 cfs in Maroon Creek.

A 2007 vote by Aspen citizens overwhelmingly supported the $6.1 million project, with 77 percent of the public voting for it.

A conduit exemption is a more expeditious, less expensive way to bring the hydro project online, compared to applying for a new hydro license with FERC, city officials said.

They say the environmental requirements are stringent for a conduit exemption, and neither an EIS nor an environmental assessment (EA) is required.

If Aspen applies for a new license instead of a conduit exemption, FERC may require an EA or EIS. If either is required in the licensing process, FERC would oversee the analysis. City officials say that would result in considerable expense and delay, but no more environmental protection.

The environmental analysis Aspen has undertaken to date, in addition to the new studies the state wildlife division has requested, will be the same analysis that would be required for an EA or EIS, according to city officials. The only difference is that the city is overseeing the studies, which means more of a commitment to local environmental issues, a quicker project time frame and much less money.

“If FERC oversees these environmental analyses, there is no guarantee that they will seek increased in-stream flow or increased environmental protections,” said Phi Overeynder, director of public works.

The city tentatively plans to begin construction on the conduit May 1.

Paul Noto, an Aspen-based water attorney who represents several residents who live along Castle Creek and near the proposed facility, said in November that if the city of Aspen touts itself as an environmental leader, it ought to engage in a full environmental review of its proposed project.

If approved, the water would travel down a 42-inch pipe, supplying the hydro plant with approximately 25 cubic feet per second (cfs) coming from Castle Creek and 60 cfs out of Maroon Creek.

The city diverts water from both creeks for the primary purpose of supplying municipal water and maintains the in-stream flow of 12 and 14 cfs. The third priority would be for hydroelectricity, but if there isn’t enough water available in a dry year or during certain times of the year, it wouldn’t be diverted, officials have said.

The project would utilize existing water rights, head gates and water storage of the original Castle Creek hydroelectric plant, which met all of Aspen’s electric power needs from 1892 through 1958, when the plant was decommissioned.

The facility’s turbine and generator would be designed to convert the force of falling water into electric power. The water comes from Thomas Reservoir, which is located at the top of Doolittle Drive and is the home of the water treatment facility.

The electricity would be placed on the city’s grid and taken up to the water treatment campus to power those facilities, and to potentially produce hydrogen for hydrogen fuel cells and hydrogen vehicles.

When completed, the 1.05 mega-watt facility is expected to increase electric production by 5.5 million kilowatt hours annually. That power production will prevent more than 5,000 tons of carbon dioxide from entering the atmosphere each year, officials said.

It would generate renewable energy for the city and increase its supplies by 8 percent over its current level of about 75 percent.

City officials say that switching from primarily coal-fired energy purchases to hydroelectric power production would represent a 0.6 percent community-wide reduction in carbon emissions based on a 2004 greenhouse gas emission inventory.


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