Gravity dam
From Aspen Journalism (Brent Gardner-Smith):
A top utility official with the city of Aspen voiced his support last week for building “small reservoirs” on a number of streams in the Roaring Fork River watershed, including on Hunter, Castle, Maroon, and Avalanche creeks.
“Small reservoirs would improve stream flow on tributaries,” said Mike McDill, deputy director of utilities for the city of Aspen, referring to the ability to store water in the spring and release it later during low-flow periods.
“A small reservoir on Castle Creek would improve the stream health on Castle Creek and also help our drinking water reserves,” McDill said. “I think there may also be benefits to Hunter Creek, Maroon Creek and maybe even Avalanche Creek. All of our tributaries could use that kind of small reservoir and stream-flow calming.”
Today, the city of Aspen owns two diversion dams, one on lower Castle Creek next to Dick Butera’s estate, and one on lower Maroon Creek near the T-Lazy Ranch. Both of the dams are river wide and completely block fish passage, but they do not form reservoirs of water behind them.
McDill also said the city fully intends to keep its options open for two large dams on both upper Castle and Maroon creeks, which he referred to as “serious water storage reservoirs.”
McDill’s remarks were made during a public meeting of the Roaring Fork Watershed Collaborative, held at the Third Street Center in Carbondale.
At the watershed meeting, consulting engineers from SGM were facilitating a group-planning exercise in an effort to determine the top three water projects in the Roaring Fork River basin for inclusion in the forthcoming statewide Colorado Water Plan.
The effort did not result in a definitive shortlist of water projects, and no one else at the meeting spoke in favor of Aspen building new dams.
The Colorado River Basin Roundtable is slated to finalize a water project list for the entire Colorado River basin March 23.
“Serious water reservoirs”
McDill represents the city of Aspen on the Colorado Roundtable, and over the past year has consistently said the city needs to develop or acquire water storage.
“The city of Aspen, most of the cities in the region, none of them have any storage,” McDill said. “Their storage is snowpack, as is ours. I can tell you that that works great in the spring, works great through the summer. But believe it or not, our times of greatest concern are January, February, March, because Castle Creek, where we take most of water, is so low that we have to send a crew out almost every morning to chip the ice off of our intake bars, because the development of an inch or so of ice is enough to block our intake.”
McDill said the city, in addition to exploring new storage options, also is developing new water-supply projects, such as a reclaimed-water system and a deep-water well originally drilled as part of a geothermal energy project.
“The reason that we are doing that and the reclaimed water system,” McDill said, “is they are all really part of this idea of continuing due diligence to try to investigate every other possible way to provide the security for our drinking water system before we go to the point of building serious water storage reservoirs.
“We have reservoir storage rights on Maroon Creek and Castle Creek,” McDill added. “We know that’s going to be a really hard sell whenever we would start to do that, so before we even try, we’re going to look at every other alternative.”
The city holds conditional water rights for dams and reservoirs on both upper Castle and Maroon creeks.
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, about a mile-and-half from Maroon Lake.
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 city’s conditional water rights for the Castle and Maroon creek reservoirs are officially on the state’s books through 2016, when the city will need to convince the state water court it is diligently making progress toward building the dams.
(Please see related stories: “Aspen’s Ruedi water buy may bolster prospect for new dams on Castle and Maroon creeks” and “City maintains rights for dams on Castle and Maroon creeks“)
Small and large reservoirs
When McDill was asked at Thursday’s meeting what his definition of a “small dam” is, he pointed to the city’s Leonard Thomas Reservoir at the city’s water treatment plant, which he said holds 14 acre feet of water. The dam at the reservoir is 19 feet tall.
“But it’s a good question,” McDill then said. “What’s a large reservoir?”
He went on to say that the conditional water rights for the Maroon and Castle creek reservoirs were “in the neighborhood of 10,000 acre-feet,” and that the other “smaller” reservoirs under discussion were in the “4,000 to 5,000 to 6,000” acre-foot range.
Editor’s note: Aspen Journalism is collaborating with The Aspen Times on coverage of rivers and waters. The Times published this story on Friday, March 13, 2015.
More Roaring Fork River watershed coverage here.
Filed under: Castle Creek Watershed, Climate Change, Colorado River Basin, Colorado Water, Maroon Creek, Roaring Fork Watershed, Water Law 
