The location of a potential dam and reservoir just below the confluence of East and West Maroon creeks, which is about a mile-and-a-half below Maroon Lake and well within view of the Maroon Bells.Smith Credit: Brent Gardner-Smith

The upper ends of both Castle and Maroon creek valleys would be the sites of two new city of Aspen water storage reservoirs and dams, under 47-year-old conditional water rights that the city has continued to keep alive.

(Please see maps of the potential Maroon Creek and Castle Creek reservoirs).

With the threat looming that global warming could eventually render Aspen’s municipal water supply system inadequate, a state water court in 2010 extended the conditional water rights necessary for the reservoirs and their dams.

The extension is good through 2016.

“It is the city’s policy to maintain and protect its water rights,” said Aspen City Attorney Jim True, pointing to a 1993 City Council resolution on water policy.

Though the plans are little known to local residents, the city has done enough procedurally with the water court to keep the projects on the table.

They are seen by officials as a long-term contingency plan.

The feasibility of the dams and reservoirs is questionable, however.

One Bureau of Reclamation study found that soil conditions in the wetlands area where the Castle Creek dam would be built would make construction difficult.

And the U.S. Forest Service has also raised objections to placing a dam and reservoir on public land near the Maroon Bells.

Looking upvalley in the vicinity of the Castle Creek Reservoir site. The river and the wetland on the valley floor between Fall Creek and Sandy Creek, two miles below Ashcroft, would be flooded behind a 170-foot dam if the city exercised its current conditional water rights. Much of the land that would be flooded is privately owned.Smith Credit: Brent Gardner-Smith

If built as currently described by the city’s conditional water rights, 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.

By comparison, Ruedi Reservoir stores about 90,000 acre-feet and Grizzly Reservoir about 600 acre-feet.

The Maroon Creek Reservoir would cover 85 acres of U.S. Forest Service land about a mile-and-a-half below Maroon Lake, which is one of the most highly visited sites in the National Forest system.

The reservoir would inundate portions of both the East and West Maroon Creek trails in the Maroon Bells-Snowmass Wilderness.

As currently conceived, 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.

The reservoir, inundating 120 acres, would affect mostly private land between Fall Creek and Sandy Creek, but would also flood a small piece of Forest Service land within the Maroon Bells-Snowmass Wilderness.

Both reservoirs would require extensive federal review as well as approvals from Pitkin County and Aspen City Council.

“Aspen will build the Castle Creek and Maroon Creek reservoirs if necessary and in the best interest of the citizens of the community,” a committee of city officials wrote to Aspen Journalism last week in response to questions.

The answers were prepared by True, the city’s Denver-based water attorney Cindy Covell, and Phil Overeynder, a utilities engineer with the city and former head of the department.

“Aspen views these reservoirs as a contingency plan,” the city officials stated. “Maintaining options is prudent municipal planning.”

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

Few in the Aspen community are aware that the city has been keeping the prospect of the two dams alive since 1965.

“I didn’t know that the city had conditional water rights for these two reservoirs,” said John Ely, Pitkin County’s attorney and in-house expert on local and regional water issues.

Sloan Shoemaker, executive director of environmental watchdog group Wilderness Workshop in Carbondale, also said he was unaware of the conditional water rights.

“I wasn’t aware of those potential reservoirs,” Shoemaker said. “I had to pick my jaw off the desk top.”

But the city’s draft “1990 Comprehensive Water Management Plan,” which informed the 1993 City Council resolution affirming the long-term planning strategy, states that “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.”

If the city were to move forward with the reservoirs, officials said a number of factors would be considered, including whether such measures as water conservation had been put in place and how much water was available in the face of a prolonged drought.

“Any construction at these sites would require extensive permitting as well as consideration of environmental values and community priorities at the time,” the city officials wrote in their responses to questions from Aspen Journalism.

They also noted that the conceptual design of the reservoirs would likely change during a review process.

City officials have barely mentioned the reservoirs in the context of a proposed hydropower facility on lower Castle Creek.

A 2010 environmental report by biologist Bill Miller on Castle and Maroon creeks includes a one-sentence mention of the dams, acknowledging that the city owns the conditional water rights.

Both reservoirs would be upstream from the city’s diversion dams on lower Castle Creek and Maroon Creek, so water from the reservoirs could easily be delivered to the proposed Castle Creek hydro plant.

In 1989 the city told the water court that water from the Maroon Creek Reservoir could be used to power the Maroon Creek hydropower plant it had recently built.

But city officials said last week that “these reservoirs are not part of the Castle Creek hydroelectric project.”

A view looking downstream at the approximate location of the dam for the Maroon Creek Reservoir.Smith Credit: Brent Gardner-Smith/Aspen Journalism

The conditional water rights
date back to September 1965 when Darrel Rae, a consulting engineer for the city, laid out plans for the reservoirs.

In November 1966, Rae testified in water court that given low seasonal flows and occasional dry years, Aspen would need at least one reservoir by 1975.

He predicted that both reservoirs would likely be in place by 2000 to meet the water demands from a projected population of 30,000.

Today there are 6,600 residents in Aspen but the peak holiday population reaches about 30,000, according to the city’s 2010 Comprehensive Annual Financial Report.

The conditional water rights were first recognized by the water court in a 1971 decree which stated that the dams “shall be completed” within “a reasonable length of time.”

The city has since obtained extensions of the original decree at least eight times, and filed evidence of its diligence in 1972, 1977, 1981, 1985, 1989, 1995, 2002 and 2009.

In its September 2009 diligence filing the city told the water court “it has steadily applied efforts to complete” the reservoirs “in a reasonably expedient and efficient manner.”

“To date, the city of Aspen has not needed to construct the storage structures as it has devoted considerable resources to reducing per capita water consumption,” the city claimed in a proposed decree.

“However, during the last diligence period, the city has analyzed studies on global warming and climate change, and implications for the city of Aspen’s future water demand and supply and water management strategies.

“Such studies have indicated a widespread and large increase in the proportion of rainfall versus snowfall and the need for the city of Aspen to develop these reservoir storage rights to preserve and retain its water supply for future needs,” the city’s proposed decree said.

In October 2010 Garfield County District Court Judge James Boyd issued a new decree good until 2016.

A beaver pond off of the main Castle Creek channel in the area of the potential Castle Creek Reservoir.Smith Credit: Brent Gardner-Smith

The city’s decision to hold on to its conditional water rights differs from a recent decision by the Colorado River District and the West Divide Water Conservancy District in Rifle.

Those districts voted in 2011 to abandon conditional water rights for the 129,000-acre-foot Osgood Reservoir, which would have flooded Redstone, and to reduce a potential Placita Reservoir, located below Marble, from 62,000 acre-feet to 4,000 acre-feet.

“It was not economical, it wasn’t politically feasible, and there certainly was not institutional or local support for such a project,” Chris Treese, the external affairs director for the Colorado River District, said at the time about the Osgood Reservoir.

A number of groups are preparing to go to trial in water court in August 2013 to oppose the conditional water rights for the smaller Placita dam from being renewed, including Pitkin County, American Rivers, and Trout Unlimited.

In 1970 the Bureau of Reclamation drilled three test bores at the Castle Creek dam site and found 142 feet of “pervious sand gravel” piled up below the valley floor, which meant it would be hard to keep water in the reservoir from seeping out.

It also said “the bedrock was also quite broken and believed to represent a possibly dangerous fault zone.”

The bureau concluded it was a relatively poor location for a dam and told city officials it would not study the Castle Creek Reservoir any further.

The city recently acknowledged the 32-year-old drill tests and said that “costly mitigation of soil conditions, such as grouting and lining,” would likely be necessary for the Castle Creek Reservoir.

More recently, the U.S. Forest Service weighed in on both reservoirs.

A November 2009 letter from Scott Fitzwilliams, forest supervisor for the White River National Forest, told the city the reservoirs would require federal review and “would not comply with the goals and objectives” of the current forest plan.

“For example, the Maroon Creek Reservoir, as currently sited, would not be compatible with the specific management of this highly visited area for the protection of its high scenic value,” Fitzwilliams wrote. “Both proposed structures would conflict with our management objective to maintain or improve long-term riparian ecosystem conditions in the forest.”

Both reservoirs would flood what are today complex wetland areas.

A frothing hole in the woods near the potential Maroon Creek Reservoir dam site.Smith Credit: Brent Gardner-Smith

The city also got recent pushback from a private property owner in the Castle Creek Valley.

Mark and Karen Hedstrom, who own a home and 21 acres of land on what would be the upper shore of the Castle Creek Reservoir, formally opposed the city’s 2009 diligence filing in water court.

But in May 2010 the Hedstroms agreed that if the reservoir did not flood any of their land, they would withdraw their opposition.

Another property owner whose land would be flooded by the Castle Creek Reservoir, Simon Pinniger, said the notice he was sent by the city’s water attorney in Denver in 1990 obscured many of the details of the city’s reservoir plan.

“Wouldn’t it have been nice if the city had explained to the three landowners affected, in non-legal jargon and with a decipherable map, exactly how each property would be affected if the Castle Creek Reservoir is built; what would make the reservoir necessary, why it has to be located on our land and when this might happen,” Pinniger said in an email.

In 1965, the Castle Creek Reservoir was estimated to cost $790,000, while the Maroon Creek Reservoir was estimated at $770,000, according to the original plat maps of the reservoirs.

According to a 2007 report prepared for the city and Pitkin County by Grand River Consulting, reservoirs on the Western Slope now cost between $5,000 and $10,000 an acre-foot to build.

At $7,500 an acre-foot, the 9,062-acre-foot Castle Creek Reservoir would cost $68 million and the 4,567-acre-foot Maroon Creek Reservoir would cost $34 million.

Editor’s note:
This story was also published on Monday, July 9, 2012, in the Aspen Daily News in collaboration with Aspen Daily News Managing Editor Curtis Wackerle. On Thursday, July 12, 2012, the Daily News published an editorial entitled “Get the dam plans off the books.”

Update: Since the story was published, there have been several letters to the editor about the issues raised by the story published in the Aspen Daily News. They were published on July 24 (“You’d better believe it”), on July 25 (“Don’t buy into scare tactics from hydro opponents”), and on July 26 (“An honest discussion on hydro”).

Additional Documents and Story Notes:

There are also a number of other documents related to this story that are not specifically mentioned in the above story.

The draft 1990 Comprehensive Water Management Plan.

This document is apparently the most recent, complete and up-to-date Comprehensive Water Management Plan for the city of Aspen. It is, at least, the most recent document provided to Aspen Journalism through a Colorado Open Records Act request.

We have asked if the draft document was ever finalized, but apparently the draft document informed the 1993 water policy resolution but was not ever finalized. If it was, we’ve yet to receive a copy.

We’ve posted the complete 252-page document on DocumentCloud and annotated the sections relevant to the two reservoirs. One section is also linked above in the body of the story.

  • 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

The authorizing legislation for the Fry-Ark project

Here is the authorizing federal legislation for the Fry-Ark project which put forward the Castle Creek Reservoir as something of a consolation prize for taking the Roaring Fork Reservoir off the books. That reservoir was once proposed to be built three miles east of Difficult Creek on the Roaring Fork River. Here is the plat map (albeit in sideways format) for that reservoir, now apparently taken off the books. More on the reservoir can be found in this historical note from The Aspen Times.

1987 letter from Aspen Assistant City Engineer Chuck Roth

This letter provides some insight into how the city viewed the prospect of the reservoirs in 1987. Roth asks a consultant for more information about using the Maroon Creek Reservoir for hydropower and about the prospect of recreation on the new body of water.

Guide to Colorado Well Permits, Water Rights, and Water Administration

There is a good brochure from the state on Colorado water rights, including a definition of conditional water rights. In its definition of a “conditional water right” it states that “it gives the holder of that right time to complete a project as long as they diligently pursue completion of the project.”

Another view of the potential dam and reservoir site just below the confluence of East and West Maroon creeks. The Maroon Bells, the most photographed peaks in Colorado according to the U.S. Forest Service, are visible in the background up West Maroon Creek. Credit: Dan Bayer

Editor’s note: This article was updated on Jan. 30, 2017 to correct a reporting mistake. The article had stated that a water court referee had approved Aspen’s diligence arguments regarding climate change, but the reference was to a proposed decree submitted to the court by Aspen’s attorney, and was not the water referee’s document.

Brent Gardner-Smith

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...

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