The shimmering surface of Rueter-Hess reservoir seems out of place in arid Douglas County, where almost all of the water resources are in aquifers a quarter-mile under ground.
Yet the $195 million body of water, southwest of Parker, is poised to play a crucial role in providing water to one of the fastest-growing metropolitan areas in the U.S.
As recently as a few years ago, developers were content to tap the seemingly abundant Denver Basin aquifer to serve the thousands of new homes built each year along the southern edge of metro Denver.
But a problem arose. As homebuilding in Douglas County exploded, the groundwater that once seemed abundant turned out to be finite. Land developers and utilities found that the more wells they drilled into the aquifer, the more grudgingly it surrendered water.
“Now we have a lot of communities on a diminishing aquifer,” said Eric Hecox, executive director of the South Metro Water Supply Authority, a consortium of 14 water suppliers that serve 300,000 residents.
As water pressure in the Denver Basin steadily declines, developers and water utilities that rely on the aquifer are being forced to drill more wells and pump harder from existing wells.
Enter Rueter-Hess. The massive storage facility — 50 percent larger in surface area than Cherry Creek reservoir — aims to help developers wean themselves from groundwater by shifting to other sources.
The reservoir anchors a multifaceted water plan for the south metro area that includes the purchase of costly but replenishable surface water, reuse of wastewater and a greater emphasis on conservation.
Douglas County, long a magnet for builders enticed by easy access to Denver Basin aquifers, is taking the water issue seriously.
A new proposal floated by the county government would give developers density bonuses — up to 20 percent more buildout — for communities that reduce typical water consumption and commit to using renewable sources for at least half of their water.
“In the past, the county had not taken an active role in water supplies because groundwater was sufficient,” said Douglas County Commissioner Jill Repella. “But we understand that we cannot continue to be solely reliant on our aquifers. What we’re doing today will help us plan for the next 25 years.”
Parker Water and Sanitation District launched construction of Rueter-Hess in 2006 and began gradually filling the reservoir in 2011, fed by excess surface and alluvial well flows in Cherry Creek.
Partners in the project include Castle Rock, Stonegate and the Castle Pines North metropolitan district. Parker Water and Sanitation district manager Ron Redd said he expects more water utilities to sign on for storage as they begin acquiring rights to surface water.
The chief source of new supplies will be the Water Infrastructure and Supply Efficiency partnership, or WISE, in which Denver Water and Aurora Water will sell an average of 7,250 acre-feet a year to 10 south-metro water suppliers beginning in 2016. Most of them are expected to purchase storage for the new water in Rueter-Hess. An acre-foot is generally believed to be enough to serve the needs of two families of four for a year
Parker Water and Sanitation also is exploring ways to develop recreational uses at the dam — including hiking, camping, fishing and nonmotorized boating — through an intergovernmental agreement with other Douglas County entities.
Even three years after opening, the reservoir’s stored water has reached just 13 percent of its 75,000-acre-foot capacity. Yet Rueter-Hess is the most visible icon in Douglas County’s search for water solutions.
At stake is the ability to provide water for a county that in the 1990s and early 2000s perennially ranked among the fastest-growing in the nation. The number of homes in Douglas County has soared from 7,789 in 1980 to more than 110,000 today, an astounding increase of more than 1,300 percent.
The building boom slowed after the 18-month recession that ended in June 2009. Growth rates that had reached as high as 10 percent to 15 percent a year during the 1990s ratcheted down to about 1 percent to 2 percent.
But as the economy has begun recovering, Douglas County is once again “seeing high levels of demand” for new residential development, said assistant director of planning services Steve Koster.
One of the biggest Douglas County projects in decades is Sterling Ranch, a proposed community of 12,000 homes south of Chatfield State Park.
The 3,400-acre ranch sits on the outer fringes of the Denver Basin aquifer, making it a poor candidate for reliance on the basin’s groundwater.
As a result, the project developer will employ a mixed-bag of water resources, including an aggressive conservation and efficiency plan; surface-water purchases from the WISE program; well water from rights owned by Denver billionaire Philip Anschutz; and a precedent-setting rainwater-collection program.
Sterling Ranch managing director Harold Smethills described the Rueter-Hess concept as “brilliant,” even though his development has not yet purchased any of the reservoir’s capacity.
“You just can’t have enough storage,” he said.