The view looking upstream from Castle Creek in the area that would be flooded by a Castle Creek Reservoir.
The view looking upstream from Castle Creek in the area that would be flooded by a Castle Creek Reservoir.Smith Credit: Brent Gardner-Smith

City of Aspen water officials are now working to update the city’s comprehensive water management plan and the process could inform future decisions about potential new dams, reservoirs and hydropower plants.

The 260-page plan, covering all aspects of the city’s water supply and use, was last updated in 1990 and a revised version is expected to be finished in 2014.

(Please see links to the five sections of the plan at the bottom of this story, as well as links throughout the story to specific parts of the document annotated in DocumentCloud.)

The plan was supposed to be updated every 10 years, so a revised version is more than 20 years overdue. And the emerging reality of climate change and long-term drought could make the analysis of future water supplies especially relevant.

A recent study published in “Nature Climate Change” concluded that the headwaters of the Colorado River — which include Castle and Maroon creeks — could see a 10 percent reduction in flow by 2040.

When complete, the updated water plan should give Aspen officials new insight into, among other things, the potential need to build two large dams on Castle and Maroon creeks to store spring runoff to meet municipal water demands.

“We’ve got studies that we’re going to do in the next two years that will inform us about the need for those reservoirs,” said Debbie Quinn, Aspen’s assistant city attorney, who works on city water issues.

The planning process could afford local citizens the first real chance in several decades to discuss and debate the two potential reservoirs in public.

The 1990 plan states that “the Maroon Creek Reservoir and Castle Creek Reservoir were conditionally decreed in 1971 for 4,567 acre-feet and 9,062 acre-feet respectively. The reservoirs are the final step to be implemented in the upgrading of the entire Aspen water supply system, to ensure reliability of water quality and quantity during successive drought years.”

While the 1990 plan was left as a working draft and never formally adopted by City Council, it has nonetheless guided official city water policy and subsequent directives from council to staff members for more than 20 years.

Many recommendations in the 1990 plan have been successfully implemented, including replacing leaking municipal water pipes and setting up a rate structure designed to encourage water conservation.

“Use peaked in 1993 at a much higher number, despite the fact that we’ve got two-and-a-half times as many customers hooked up to our system,” said Phil Overeynder, a senior water engineer with the city of Aspen.

But the 1990 plan also called for the active investigation into the feasibility of reservoirs on Castle and Maroon creeks, something the city has not done.

“The city manager shall seek proposals from engineers specializing in the fields of engineering, geology, and hydrology to determine the supply available to each reservoir, for the purpose of determining how to best design, schedule, and utilize existing system and new system development, as well as to determine optimum reservoir construction,” the plan states.

Toward that end, the 1990 plan called for the city to spend $50,000 in 1993 for a “feasibility study for Castle Creek Raw Water Reservoir.”

And, while acknowledging that building either reservoir would be a “major undertaking” for the city, the 1990 plan also called for spending $24 million to build the Castle Creek reservoir in 2000 and $15 million to build the Maroon Creek reservoir in 2005 as part of a “15-Year Water Improvements Program.”

The city has not studied in detail, or built, the reservoirs, both of which were envisioned to include a hydropower component. The city has, however, periodically filed to maintain the conditional water rights tied to both reservoirs, citing the 1990 plan and subsequent City Council policy as the basis for its actions.

(Please see related story: “City maintains rights for dams on Castle and Maroon creeks.”)

And since the 1990 plan was written, city officials have become increasingly concerned that global warming will reduce future water supplies and increase the need for the reservoirs.

“It is the ultimate hedge against climate change,” Overeynder said about a reservoir in which to store water from spring runoff. “It is the one option that you know will produce the results that you are ultimately after if you are faced with climate change.”

But the “ultimate hedge” may not be an easy bet to make.

The 170-foot-tall dam, and resulting reservoir, on upper Maroon Creek below Maroon Lake would be wholly on Forest Service land and the project conflicts with current White River National Forest regulations regarding wetlands and scenic values.

And the 155-foot-tall dam and reservoir on upper Castle Creek below the former Elk Mountain Lodge property would be mainly on private land, where results from test drills in 1970 found poor soil conditions for a reservoir.

“It’s still got very high hurdles in terms of the cost, environmental impacts, public perception, permitting, all of those things — but it is a tool the city has because of the filing it made in the 1960s,” Overeynder said about the dams and reservoirs.

One of the first steps in updating the 1990 comprehensive water management plan is to update the city’s raw water supply study, which will be done in 2013.

That study will likely take a much closer look at potential reductions in water supply due to global warming, which is expected to cause lower snowfall amounts and earlier spring runoffs.

With climate change in mind, city water officials are now loath to walk away from the prospective dams on Castle and Maroon creeks, as the Colorado River District recently did from a potential large dam below Redstone on the Crystal River.

“Given that we’re sitting here in 2012, and you’re talking about things decades from now, it is still reasonable and prudent to keep that as part of what we look at,” said David Hornbacher, the city’s director of utilities and environmental initiatives, about a reservoir.

But if climate change is already happening, as the water officials themselves suggest, will it really be “decades” before the city needs to store water in two new reservoirs?

It’s an unanswered question.

“We don’t know how big the hole is,” Overeynder said about potential water shortages. “We’re saying, let’s do the study first, and then decide.”

The 1990 comprehensive water management plan was also bullish on hydro, citing the city’s recent success with developing hydro facilities at Ruedi Reservoir and on Maroon Creek.

The plan states that “the city will continue to evaluate the hydroelectric potential of area streams and city water projects, and continue to expand the hydroelectric generating capacity of the city and the Roaring Fork Valley whenever technically and economically feasible.”

It also called for a series of site-specific reviews to be conducted on potential locations around Aspen for new hydro plants.

While such studies were not done, city officials did conduct a planning effort in 2006 that screened out a number of options and the decision was made to build a new hydro plant under the Castle Creek bridge where a pioneering hydro plant had generated power from the late 1880s to 1958.

In 2007, Aspen voters approved a new hydro project on the site.

But by November 2012 a majority of voters had soured on the increasingly expensive and contentious project and they passed an advisory question directing the council to take no further action on the new plant.

The City Council is now slated to discuss potential next steps for the hydropower project in January.

The council will do so against the backdrop of November’s vote against a specific hydro plant, but also with the knowledge that the city’s long-standing policy is to expand its hydropower assets whenever it is “technically and economically feasible.”

Editor’s note:
This story was published in collaboration with the Aspen Daily News, which ran the story on Sunday, Jan. 6, 2013.

Aspen’s 1990 Draft Comprehensive Water Management Plan:

Draft 1990 Comprehensive Water Management Plan, part 1
Draft 1990 Comprehensive Water Management Plan, part 2
Draft 1990 Comprehensive Water Management Plan, part 3
Draft 1990 Comprehensive Water Management Plan, part 4
Draft 1990 Comprehensive Water Management Plan, part 5

Maps of the potential reservoirs:

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

A map 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. Source: Aspen Journalism via the Pitkin County GIS/Mapping Department

[documentcloud id=”394353-potentialreservoir-castlecreek-1″]

This map 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. Source: Aspen Journalism via the Pitkin County GIS/Mapping Department

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...