A beaver dam and wetland on the portion of Castle Creek that the city of Aspen has designated as the location for a potential 170-foot-tall dam and a 9,000 acre-foot reservoir.
Credit: Brent Gardner-Smith

Aspen City Council tonight will consider entering into a water contract with the federal Bureau of Reclamation that could bolster the prospects of two potential dams being built someday on upper Castle and Maroon creeks.

The Dec. 3 meeting is a follow-up to a meeting on Nov. 26, where council members and water department officials discussed the option to contract for 400 acre-feet of Ruedi water for augmentation purposes.

The $511,000 contract is seen by city officials as a way to help protect the city’s future diversion and storage projects from being called out by downstream water owners.

For example, if irrigators in Grand Junction with senior water rights on the Colorado River called for water from the Roaring Fork River watershed — including the city’s water — the city could ask Ruedi to release water instead and it would run down the Fryingpan to the Colorado River.

That way, the city would not have to drain the ponds it plans on its golf course and park lands to meet the demand. Or, according to city officials, they would not have to fully drain one or both of two potential reservoirs on upper Castle and Maroon creeks, should they be built in the future.

As such, the first meeting on the Ruedi water contract produced a brief, and rare, discussion of the potential for the city to build the dams on upper Castle and Maroon creeks.

The stretch of Maroon Creek, just below the confluence of East and West Maroon creeks, where city of Aspen plans show a large dam. City officials say climate change may someday make either the Maroon or Castle creek dams a good option, and buying water in Ruedi now could benefit the reservoirs if they were built.
Brent Gardner-Smith/Aspen Journalism

The stretch of Maroon Creek, just below the confluence of East and West Maroon creeks, where city of Aspen plans show a large dam. City officials say climate change may someday make either the Maroon or Castle creek dams a good option, and buying water in Ruedi now could benefit the reservoirs if they were built.

Aspen’s conditional water rights

“Aspen holds conditional water rights for raw water storage on both Castle and Maroon Creek totaling in excess of 15,000 acre feet,” says a document attached to a Nov. 14 memo from Phil Overeynder, a utilities engineer with the city who also is the point person for municipal water projects.

If built as currently described by the city’s plans, which were first presented to a water court judge in 1965, the Maroon Creek reservoir would store 4,567 acre-feet of water behind a 155-foot-tall dam just below the confluence of East Maroon and West Maroon creeks.

While only about a third of the size of the Paonia Reservoir, which can hold 15,553 acre-feet when full, a Maroon Creek reservoir would still cover 85 acres of U.S. Forest Service land about a mile-and-a-half below Maroon Lake. It would also inundate portions of both the East and West Maroon Creek trails in the Maroon Bells-Snowmass Wilderness.

The Castle Creek reservoir would hold 9,062 acre-feet of water behind a 170-foot-tall dam located about two miles below the historic town site of Ashcroft. It would inundate 120 acres of mostly private land between Fall Creek and Sandy Creek and would also flood a small piece of Forest Service land within the Maroon Bells-Snowmass Wilderness.

[documentcloud id=”394355-potentialreservoir-marooncreek-1″]

A map (above) of the potential Maroon Creek reservoir. (Use the zoom slider in the upper right corner and the framing bars for a closer look.) The city of Aspen holds conditional water rights for the reservoir, which, if ever built, might differ from this depiction. This is, however, an accurate representation of the city’s current conditional water rights for the reservoir based on a 1965 plat map on file with Pitkin County. A larger view and a link to the original pdf is available on DocumentCloud.

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This map (above) depicts the potential Castle Creek reservoir and the private property ownership in the area based on the city’s 1965 conditional water rights and a plat map updated in 1977. City officials note that the upper end of the reservoir should be shown ending below the property owned by the Hedstroms, due to a 2010 agreement not to flood their property. The city also questions whether Castle Creek Road would be flooded to the extent shown. A larger view and link to the pdf is on DocumentCloud.

Unwise to eliminate the option

“The existing Water Management Plan makes it clear that other less costly and intrusive alternatives would be implemented prior to constructing reservoirs,” Overeynder told council in the attachment to his memo.

“However, it would be unwise to eliminate these two projects as options until other options are evaluated more fully and proven as a feasible means of addressing future potential changes in climate and resulting runoff patterns,” he wrote.

The city’s conditional water rights for the dams are on the books until at least 2016, at which point the city will need to convince a judge in water court that it “can and will” build the reservoirs and that it is diligently making progress toward doing so.

Purchasing augmentation water in Ruedi to the benefit of the potential reservoirs could help the city make its case in water court in three years’ time, according to Pitkin County Attorney John Ely.

“It protects their position,” he said.

Ely also noted that Pitkin County considered purchasing additional water from Ruedi, but couldn’t find a good reason to do so.

Overeynder further established the connection between the Ruedi water purchase and the Castle and Maroon reservoirs in an attachment to the Nov. 14 memo.

“If constructed, these two reservoirs could benefit from Ruedi water in two ways,” he wrote.

One way is to establish a “minimum pool” for “aesthetic and recreational purposes,” Overeynder wrote.

A minimum pool is the amount of water always maintained in a reservoir. With Ruedi water, the city could release water down the Fryingpan and leave water in one or both of its reservoirs that might otherwise be called out.

“Second,” Overeynder writes, “future oil shale development may, to the extent it occurs, develop a more or less permanent water shortage on the Colorado River mainstream, limiting opportunities to store water from Castle and Maroon Creek.

“A supplemental release of Ruedi water would alleviate this condition (in part) and increase opportunities to store water from Castle and Maroon creeks.”

Looking down Maroon Creek this summer toward the location of a potential 155-foot-tall dam and a 4,567 acre-foot reservoir. The area includes a complex wetland and stream-channel pattern.
Credit: Brent Gardner-Smith/Aspen Journalism

Quiet renewals

The city has quietly renewed the water rights for the two reservoirs eight times since they were decreed in 1971.

Today the city maintains two small diversion dams on both lower Castle and Maroon creeks. They send water into pipes and then to the city’s water plant at the tiny Thomas Reservoir above Aspen Valley Hospital. Those dams only divert water, and do not store it.

At the Nov. 26 council meeting, Overeynder told the council that climate change is shifting runoff patterns and the spring melt is coming earlier than it used to, which means there could be less water for municipal uses in the late fall and winter.

“That will change your need for water and therefore the need for new projects,” Overeynder said. “And this would be the last priority, and the absolute last thing we would do, would be to construct reservoirs on Castle and Maroon creeks.”

While Overeynder stressed that the reservoirs are only a last resort, he is recommending that the city take steps to secure the potential for the dams to be built someday.

On the Crystal River, Pitkin County, American Rivers and other groups are suing the West Divide Water Conservancy District and the Colorado River District in an effort to force them to abandon conditional water rights that would allow for a dam on the upper Crystal at Placita.

To date, there has been no organized opposition against the city’s conditional water rights tied to dams on upper Castle and Maroon creeks. The rights were extended for another six years in 2010 by a judge in water court after the city reached an agreement with a private landowner on Castle Creek not to flood their property.

Castle Creek and adjacent wetlands this summer. The city's plans tied to its conditional water rights show a 170-foot-tall dam and a 9,062 acre-foot reservoir here.
Credit: Brent Gardner-Smith/Aspen Journalism

More info requested

At the City Council meeting on Nov. 26, there was little discussion among the five council members about the idea of someday building two large dams, although council member Adam Frisch said the public might want more information about them.

Frisch suggested that there should be more community dialogue about the city’s long-term water plans, the dams and why the city thinks they might be necessary in the face of climate change.

“ … I think fleshing that out, so to speak, would be helpful for us and the public to understand that if we don’t do this there are some other options that might have to happen,” Frisch said. “ … If we have peak runoff in March, that’s not a small thing … to have happen here — to switch from June to March.”

At today’s meeting, which starts at 4 p.m., the council is scheduled to discuss the contract for Ruedi water, but it is not clear if council members will discuss its ties to the two potential dams.

Aspen, along with 17 other entities, including the Snowmass Water and Sanitation District, are in the early stages of agreeing to contract for water stored in Ruedi.

The Bureau of Reclamation is selling 19,585 acre-feet of water in order to pay off a remaining $34 million debt on the reservoir, which was built in 1968.

Editor’s note: This story was published in collaboration with the Aspen Daily News, which published the story on Monday, Dec. 3.

The Daily News covered the Aspen City Council meeting on Dec. 3 and published a follow-up story on Dec. 4, 2012.

For more information, please see “City maintains rights for dams on Castle and Maroon creeks” on Aspen Journalism.

Brent Gardner-Smith, the founder of Aspen Journalism, and who served as AJ’s executive director until August 2021 and as editor from 2011-2020, is the news director at Aspen Public Radio. He's also been...