The upper ends of both the 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.
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. The U.S. Forest Service has also raised objections to placing a dam and reservoir on public land near the Maroon Bells.
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 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. It would require extensive federal review.
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 townsite 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.
“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.”
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.”
1965 water rights
The conditional water rights date back to September 1965 when Dale Rae, a consulting engineer for the city, laid out plans for the reservoirs.
A view from the approximate location of the 15-story dam that would be necessary to create the Maroon Creek Reservoir as described by the city of Aspen’s conditional water rights. The iconic Maroon Bells would be well-within view of the reservoir, which like other reservoirs in the region, would not always be full of water.
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.
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.”
A court official, known as a water referee, agreed.
“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 unnamed referee reported.
“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 referee found.
In October 2010 Garfield County District Court Judge James Boyd agreed with the water referee and issued a new decree good until 2016.
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.
Federal agencies skeptical
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.
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 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: Aspen Journalism is a nonprofit news organization working in the local public interest. More information and additional images are available at www.AspenJournalism.org.