Aspenites weigh in on water rights for possible reservoirs on Castle, Maroon creeks |

Aspenites weigh in on water rights for possible reservoirs on Castle, Maroon creeks

This image by the conservation group Wilderness Workshop shows how a possible city of Aspen dam and reservoir would affect Maroon Creek Valley.
Wilderness Workshop/courtesy image |


The city of Aspen is looking at Maroon and Castle Creeks as long-term supplies for its water. While there is no current plan to develop dams and reservoirs,it has been maintaining conditional water rights since 1971 as an option.

Possible Castle Creek Reservoir is 9,062 acre feet

Possible Maroon Creek Reservoir is 4,567 acre feet

The city of Aspen took what an environmental consultant labeled an unusual and amazing step Thursday night by asking residents if it should retain conditional water rights tied to dams and reservoirs on two cherished streams.

Environmentalists didn’t show up in droves with pitchforks or divining rods in hand, but roughly 40 people outside of city government attended to learn more and weigh in.

The city filed for water rights on Maroon and Castle Creeks in 1965 as part of a long-term plan to address water supply. Aspen was awarded a “place in line” in 1971 by a water court. The conditional water rights were awarded for a proposed 9,062-acre-foot reservoir in Castle Creek Valley and 4,567-square-foot reservoir in Maroon Creek Valley.

The city has to submit a diligence filing periodically, currently every six years, to show “they’re making progress on these water rights and not just sitting on them,” said Larissa Read of Common Ground Environmental Consulting. She facilitated the city meeting.

The filing is routine, she said, and it’s unusual for a governmental entity to ask its residents if it should pursue them. Having faced a controversy over developing hydropower in the Castle Creek Valley, the city is erring on the side of caution by inviting public input on the unrelated water-rights issue.

“What would happen to the water if we didn’t keep it?” asked Scott Writer, a candidate for Pitkin County commissioner. Specifically, he asked, if it would go to the Eastern Slope.

The answer isn’t easy, said David Hornbacher, director of utilities and environmental initiatives for the city of Aspen. Hundreds of downstream requests have been filed for water in the streams. He said he didn’t know who would have priority.

Hornbacher assured the audience that Aspen has no immediate plan to build the reservoirs, but it wants to make sure it keeps options open for supply.

The city has looked at demand assuming zero growth, the 1.2 percent annual growth it has historically experienced and 1.8 percent growth forecast by the state demographer.

It’s also examined demand based on climate-change models that would result in higher temperatures creating peak runoff earlier in the spring and diminished runoff earlier in the summer.

“Without climate change, we wouldn’t really have an issue,” said Ashley Perl, director of Aspen’s Canary Initiative, a broad-ranging plan to examine global warming and develop strategies to reduce the effects on Aspen or to adapt to them.

A handful of attendees asked questions during a presentation by city officials and in small-group discussions that followed. Will Roush, conservation director for Wilderness Workshop, asked how much of the capacity of Maroon and Castle creeks is currently being used. That obviously depends on the season, Hornbacher said, but “our actual use is below our rights.”

Castle and Maroon already supply Aspen’s domestic water supplies.

A resident of Castle Creek Valley who didn’t give his name expressed concern for the health of the streams as well as the fish and other creatures that depend on them. If the dams and reservoirs get built, a minimum streamflow of roughly 14 cubic feet per second would have to be maintained. The concerned resident said that’s a legal requirement, but not one that sustains life.

City staff was compiling participant comments and will summarize them for the Aspen City Council for a work session that will be held in late September or early October.

Residents also can weigh in by sending comments to waterrights@city​ by Aug. 19. Public hearings are unlikely since the city has to submit its diligence filing by late October, officials said Thursday night.

Even if the city gets its conditional water rights renewed, there’s no guarantee the reservoirs will be constructed.


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