Bolts Lake construction may begin as soon as 2027
Providing 1,200 acre-feet of water to Eagle County creates engineering, permitting challenges
Eagle River Water & Sanitation District/Courtesy image
At the Dec. 7 Eagle River Water & Sanitation District meeting, new details were shared on the project to create the Bolts Lake Reservoir. According to the update, a design concept for the reservoir should be ready by early next year, and construction may begin as soon as 2027, and finish in 2029. This timeline, however, is subject to a series of expensive and complicated permits that may stall the project at any point.
Background
The Eagle River Water & Sanitation District and Upper Eagle Regional Water Authority bought the Bolts Lake property from Battle North in 2022 after recognizing the need for increased water storage to accommodate a variable climate and more customers.
The Bolts Lake reservoir should provide storage for up to 1,200 acre-feet of water, which will supplement the valley’s streams in dry times. One acre-foot of water is the amount of water it takes to flood one acre of land one foot deep.
While the district already runs the Eagle Park Reservoir, Bolts Lake will become its go-to source when completed.
“We’re probably going to use this source first, particularly in a really dry year in the summertime, because we can prop up streamflows, it hits things quicker, so we can operate it more efficiently. Eagle Park (Reservoir) would be the backup source,” said Jason Cowles, director of engineering and water resources at the Eagle River Water & Sanitation District.
Support Local Journalism
Filling the reservoir
Following research and physical studies, the current plan is to structure two sources to fill the Bolts Lake Reservoir. Cross Creek, which flows through the Holy Cross Wilderness Area, and has an already-established diversion point along U.S. Highway 24 south of Minturn, will be the primary source. Cross Creek is the easier source to fill the reservoir with, as it can be done with gravity.
The Cross Creek water will be supplemented by water from the Eagle River. A pump system will be installed to ferry water from the Eagle River to the Bolts Lake Reservoir, which will ultimately have lower construction and lower wetland impacts than using gravity.
Cross Creek will supply approximately 1,085 acre-feet per year, while the Eagle River has the ability to supply approximately 995 acre-feet per year, though climate change may reduce the yield from both sources over time.
There are a couple of reasons behind creating a secondary source of water for the reservoir. First, in dry years, Cross Creek may not provide enough water to fill the reservoir. When flows in Cross Creek go below 170 cubic feet per second, water physically cannot be derived from the diversion point, as water levels will be below the diversion.
Second, because Cross Creek is located in the Holy Cross Wilderness, there are limitations on construction techniques and modifications to the stream.
Relying on high flows from Cross Creek to fill the reservoir means it should fill during spring runoff in April through July, and then water will be released as demanded throughout the months of August through September.
“It will be full in early summer, and it will be slowly drained as we need it (in the) late summer and early fall,” said Justin Hildreth, water resources engineer at the Eagle River Water & Sanitation District.
Minturn
As the site is connected with Minturn, the district and authority have gone through extensive litigation with the town of Minturn to establish an intergovernmental agreement that outlines the rights of both parties. District staff will also present to the Minturn Town Council as the project moves forward. At the Dec. 6 Minturn Town Council meeting, Hildreth and Cowles talked through the current state of planning for Bolts Lake.
One of the Town Council’s biggest concerns was whether the water being diverted to the reservoir might impact Minturn’s water rights. Minturn’s water rights are senior to those of the district.
“At a certain flow level, we can’t actually get water into the Bolts Ditch intake, and so there would be no injury to Minturn’s water rights because we simply can’t divert water due to gravity once flows get lower,” Cowles said.
Design elements
Hildreth pointed out a critical design element that will need to be worked through in order to create a successful reservoir. As there is groundwater at the site and the bedrock is very permeable, the reservoir will need a liner to keep the filled water separate from the water already at the site. District and contracted engineers will review and decide whether to use a clay-based liner or a synthetic liner, as well as selecting the best method to drain the groundwater to avoid breaching the liner.
To ensure the reservoir has the capacity to hold 1,200 acre-feet of water, the top of the dam will be 8,153 feet, and the water surface would stop three feet below that, at 8,150 feet. The height of the old dam at Bolts Lake, which was breached, was 8,218 feet.
The east dam, which faces U.S. Highway 24, will be 56 feet tall, and the water there will be 53 feet deep. The southwest dam, near Tigiwon Road, will be 23 feet tall, and the water there will be 48 feet deep.
Timeline
District staff are currently reviewing applications to select the firm that will serve as the program manager for the site, which will be under contract in February 2024. A preliminary design plan for the reservoir site is expected from the Seattle-based engineering firm Shannon & Wilson in March 2024.
The actual timeline for the project is lengthy, in part due to the need to procure expensive and complicated federal permits. Hildreth said district staff expects the federal permitting process to take at least two years, estimated to be from 2024 to 2026. Following federal permits, the project will need county, town and construction permits, due to the amount and type of land the reservoir and its sources cover.
The earliest the estimated three-year construction process might begin is 2027, though this could be delayed at any point in the permitting process. If construction does begin in 2027, the reservoir may be completed as soon as 2029.
