Old reservoir gets makeover
February 22, 2008
SUMMIT COUNTY – The hike up to Old Dillon Reservoir, described in Mary Ellen Gilliland’s “Summit Hiker” trail guide as “a nostalgic walk for those who remember Old Dillon,” may soon undergo a radical transformation.Growing concern about the sufficiency and safety of the local water supply has prompted Dillon, in conjunction with the town of Silverthorne and Summit County, to develop a proposal to increase the aging reservoir’s capacity and improve its ability to store water, Colorado River District engineer Ray Tenney told Snake River Planning Commission members Thursday night.The proposal, now under consideration by the Forest Service for issuance of a special-use permit, would serve the increasing water needs of the county as well as provide a backup water supply for Dillon in the event of any disruptions to its existing Straight Creek inflow, he said.Built in 1939 by the original town of Dillon, the old reservoir has been maintained principally as a recreation area since the town’s relocation to its current site in the early 1960s.Its potential as a source of water independent from the Denver Water Board, however, makes the small lake too valuable to be left in an underdeveloped state.”We’ve been meeting on the (proposed) enlargement for two years,” Dillon director of public works Eric Holgerson said. Both the 2002 drought and the devastation caused by the pine beetle have intensified the desire of local authorities to develop alternative water supplies.”Luckily, we made it through in 2002,” Holgerson added. “But the pine beetle epidemic really scares me.”Water stored in the old reservoir is unusual in that it originates from Salt Lick Creek in the Wildernest area and isn’t subject to the senior water rights from the Blue River owned by Denver Water. In the complicated world of Colorado water rights, this makes the old reservoir’s water especially valuable. Construction impact The existing trail to the quiet 10-acre reservoir, a popular after-work dog-walking and casual hiking destination, begins at a parking lot on the north side of the Dam Road and climbs more than 150 feet to the lake, where it overlooks I-70 and the expanse of the “new” Dillon Reservoir. To the casual visitor, the area can appear to be natural – not an artificial lake created by two, 6-foot-tall earthen dams now obscured by plant growth.Proposed improvements, while still allowing for recreational use, will have a major impact on the site’s appearance. The reservoir’s surface area will increase from 10 acres to about 15.4 acres, but the major aesthetic change will involve construction of two modern earthen dams that will tower 20 to 25 feet about the existing structures.”It’ll look more like a dam and a reservoir,” Tenney said.Even without the enlargement, however, some construction at the site would still be necessary to maintain the dam in its present state.If work proceeds as planned on the project, hiking and fishing will be restricted temporarily, but once completed, access would resume as before.The increased capacity of the renovated reservoir from its existing 46 acre-feet to the proposed 255 acre-feet (an acre-foot is equal to about 326,000 gallons, or enough water to cover one acre with one foot of water) might prove to be a boon for fishing, Silverthorne utilities director Zach Margolies observed.”It may be deep enough to be a reproducing fishery,” he said.Independent of the proposed enlargement, the Forest Service plans to move forward this summer with its pine beetle mitigation project in the area around the reservoir, which involves removing all lodgepole pines of greater than five-inch diameter trunks at chest height. TimelineThe public comment period for the Forest Service’s scoping report on the project ends next week, and, once the agency’s formal review process is completed, the county expects to receive the special use permit it requires. Other necessary approval steps for the proposal include those of the Army Corps of Engineers and the county’s own planning process.The towns of Dillon and Silverthorne and Summit County are negotiating the establishment of an “Old Dillon Reservoir Water Authority” through an intergovernmental agreement (IGA) process. The financial obligation of each of the project’s partners will be determined based on each entity’s percentage of ownership of the final project.Engineering for the enlargement has not yet been finalized, but preliminary site work could start as soon as this year, Forest Service community planner Paul Semmer told the commission.”Optimistically, the reservoir could be drained at the end of this summer for construction to begin in 2009,” he said.Harriet Hamilton can be reached at (970) 668-4651, or at email@example.com.