City of Aspen directs staff to develop reservoirs in Woody Creek

The Aspen City Council has directed the city manager to buy a parcel of land in Woody Creek, regardless of the results of a current ballot question, and told staff to “proceed with plans to develop the Woody Creek parcel for water storage.”

The parcel is 60 acres of land now owned by Woody Creek Development Co. (WCDC) that the city plans to buy for $3 million, even if city voters reject a $5.5 million bonding question to finance the purchase in next week’s election.

And the water storage includes a variety of potential reservoirs on the WCDC property and the neighboring gravel pit, which is operated by Elam Construction.

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The biggest reservoir in the city’s options could top out at 8,000 acre-feet, would cost $81 million and require “construction of a 5,000-foot-long dam, with a 60-foot maximum section,” according to a study completed in September for the city by Deere and Ault, an engineering firm in Longmont.

The study includes four alternatives, all of which are flexible and could be adjusted, city officials said.

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The first option is to build a 1,000 acre-foot surface reservoir in the existing gravel pit. That could be built “relatively quickly, possibly within a few years,” the study says, while additional reservoirs on the WCDC site could then be completed within “the order of a decade.”

The city has no stated plans to buy the gravel pit, and the mine’s current reclamation plan, regulated by Pitkin County, does not mention turning the gravel pit into a reservoir. Nonetheless, the existing gravel pit and potential new pits on the neighboring WCDC parcel are at the center of the city’s water storage plans.

“The city and its consultant, Deere and Ault, have identified a property located in the Woody Creek area … as a high-value property for water storage,” states a resolution approved by Aspen City Council on Oct. 23. The resolution directs city manager to buy the property and staff to move forward with developing the water storage.

The WCDC parcel and the neighboring gravel pit are a short walk up a hill behind the Woody Creek post office, on a level bench formed by 200 feet of cobble, gravel and large boulders left behind by melting glaciers.

Margaret Medellin, a utilities portfolio manager in the city’s water department, said the reservoirs in Woody Creek, seen by the city as good options to potential reservoirs in Castle and Maroon creeks, will not be built anytime soon.

“Developing water storage is an effort that will take time to fully implement, as it involves property acquisition, studies, planning, permitting, engineering and design before any construction can begin,” Medellin said. “This is not an overnight process. Securing the property is the first step.”

Another step is clarifying the city’s demand for stored water.

A recent risk analysis done for the city by Headwaters Corporation suggests in a worst-case scenario in 2065, the city might see occasional shortages in the range of 2,000 acre-feet, but more work needs to be done to see how that translates into a specific water-storage need.

The Deere and Ault study recommends that the city should next “perform a water resources analysis to better understand how the (Woody Creek) site can be used to optimize the flexibility of the city’s water rights.”

Finance and water rights

Before voting to approve Resolution 139 on Oct. 23 to buy the WCDC parcel, Councilman Adam Frisch described how he saw the ballot question.

“This is an election question (and) council’s direction is that this (is) going to be purchased, it’s just a matter of how,” Frisch said. “And it’s either going to be done with using general obligation bonds, if the voters give us approval, (or) with COPs, which will be slightly more expensive, but we’re planning on executing that path if the voters don’t support us.”

Certificates of participation (COPs) are an alternative method for the city to obtain project financing.

Aspen City Manager Steve Barwick then said, “We may not use COPs. COPs would be possible. But we could also do some internal financing and use cash. You’ve identified the key issue though. It’s about the financial method rather than whether or not you are going to buy it.”

And while the city has said it intends to develop reservoirs in Woody Creek as an alternative to building potential reservoirs on upper Castle and Maroon creeks, it is still officially pursuing approval in water court for two due-diligence applications that would allow it to maintain conditional water storage rights on Castle and Maroon.

The city issued a news release in July stating its intent to transfer a portion of its water storage rights out of the Castle and Maroon creek valleys to Woody Creek, but it has not done so to date. It also is in settlement talks with the 10 parties opposing its due-diligence applications, and a status conference is set for Nov. 9.

The city holds conditional water rights to the potential Castle Creek Reservoir, 2 miles below Ashcroft, and to the potential Maroon Creek Reservoir, about a mile below Maroon Lake.

An Oct. 13 staff memo from David Hornbacher, the city’s director of utilities and environmental initiatives said the city is working to transfer “some or all of its Maroon and/or Castle creek conditional water storage rights” to the Woody Creek parcel.

In his remarks last week, Frisch said “this is about a stage of protecting water rights and hopefully, possibly, moving our water storage plans from the upper Ashcroft and Maroon Creek down to the Woody Creek area.”

Reservoir details

The potential reservoirs studied by Deere and Ault are not on either a creek or a river, but are “off-channel” reservoirs that would be filled “using a pipeline from existing ditch structures,” which are not specified.

Water in the reservoir would be released via an outlet pipe and a spillway to the Roaring Fork River, which is 150 feet below the reservoir sites.

The first phase of the first alternative in the Deere and Ault study is to build a 1,000 acre-foot reservoir in the lower end of the existing gravel pit. The reservoir would require “low asphalt cored dams” to hold back the stored water.

The next phase is to excavate the lower end of the WCDC parcel to create a 700-acre-foot reservoir. It would require a 20-foot-high dam and a “geosynthetic liner” on the bottom of the excavated area.

A second reservoir could then be dug out and lined on the WCDC property to hold 800 acre-feet of water.

Building the two reservoirs on the WCDC site would require mining 3 million cubic yards, or 4.5 million tons, of material, according to Deere and Ault.

Combined, the three reservoirs — two on the WCDC site, one in the existing gravel pit — would hold 2,500 acre-feet and would cost $73 million to build ($29,000 an acre-foot of stored water).

The next alternative “represents the maximum storage vessel that could be realized using both parcels,” according to Deere and Ault.

This reservoir requires a 5,000-foot-long dam wrapping around the downvalley end of the existing gravel pit and then along the west side of the WCDC parcel. It would store 8,000 acre-feet and cost $81 million ($10,000 per acre-foot).

It would also require excavating 11 million cubic yards, or 16.5 million tons, of gravel.

The third alternative describes a 1,000-acre-foot reservoir in the existing gravel pit and another 2,000-acre-foot reservoir on the WCDC parcel. These two reservoirs would together store 3,000 acre-feet and cost $74 million ($25,000 an acre-foot).

The fourth alternative is a small and expensive underground reservoir built on the WCDC parcel and would hold 320 acre-feet and cost $48 million ($150,000 an acre-foot).

Aspen Journalism is collaborating with The Aspen Times, the Glenwood Springs Post Independent, the Vail Daily and the Summit Daily on coverage of rivers and water. More at http://www.aspenjournalism.org.