Optimism runs high for project to fill looming water crisis in Douglas County

Along the arid Front Range, water has long replaced gold as the key to population growth. South of Denver, one water district has struck pay dirt with the construction of the Rueter-Hess Reservoir.

By Stephanie Sommers

Twenty years ago, before the population boom in Douglas County and before drought forced water restrictions on homeowners, Parker Water and Sanitation District Manager Frank Jaeger projected a water shortfall.

Since then, residents and municipalities have improved their conservation efforts through higher water rates, voluntary water restrictions, low-water use products and water-wise landscaping measures. However, with the increase in Douglas County's population projected at 65 percent over the next 30 years, conservation alone is not enough to eliminate water shortages. The area needed a new water storage system.

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Growing Demand

Designed by GEI Consulting Inc. with the area's growing water demands in mind, the $105 million Rueter-Hess Reservoir - located approximately three miles southwest of Parker on Newlin Gulch, a tributary of Cherry Creek - consists of a 16,000-acre-ft water supply reservoir, diversion structure and pump stations. When complete, it will reduce the area's reliance on groundwater and pumping water from underground aquifers.
Currently, groundwater depletion exceeds its recharge, and the PWSD is approaching maximum yield of the aquifers.

Original plans required a 135-ft-high earthen dam. But since construction began in 2004, the communities of Castle Rock, Castle Pines North and Stonegate have requested storage at Rueter-Hess. This has increased need for storage capacity from 470 water surface acres to 1,170 water surface acres and expanded the dam height to 185 ft. By comparison, Cherry Creek Reservoir is 880 water surface acres.

The municipalities that opted into Rueter-Hess will pay to store water in the reservoir.
Castle Rock plans to pay for the cost through a combination of new development impact fees and water rate adjustments. Impact fees and new customers will pay for two-thirds of Castle Rock's water program.

Multiple Phases

Weaver General Construction is the general contractor; Sema Construction did the earthwork at Rueter-Hess; Ames Construction is building the large structure conduits; and Heyward Baker is handling the curtain wall grouting.

Jim Nikkel, assistant district manager with PWSD, said that Sema finished the six million cu yds of earthmoving required by Phase I this year. PWSD plans to finish the soil cement for the dam face by Thanksgiving.

Permitting for Phase I is in process with the U.S. Army Corps of Engineers. The project is eight months ahead of schedule, and Nikkel said they expect approval by spring 2007.

While they wait for approval on Phase II, Doug Voss, project superintendent with Weaver General Construction, has his hands full overseeing construction of the 48-in. pipeline, which will divert surface water from Cherry Creek pump station to the reservoir.

PWSD has in-priority surface and ground water flows averaging up to 4,275 acre-ft per year from Cherry Creek. In addition, PWSD holds the rights to in-priority flow from Newlin Gulch.

Rueter-Hess will employ a water management system that captures storm runoff normally lost downstream. The water will be drawn from eight wells along Cherry Creek, mostly stormwater, and from advanced wastewater treatment effluent pumped by exchange.

Surface drainage will come from Newlin Gulch and Cherry Creek. Shallow wells near Cherry Creek will pump water to the reservoir for storage. Water that is normally lost through business and residential use is treated and either stored in the reservoir or returned to Cherry Creek to help maintain stream flows.

Aquifers in the Denver basin - Dawson, Denver, Arapahoe and Laramie-Fox Hills - serve nearly 85 percent of Douglas County's residents. These aquifers are limited to overlying land ownership and specific yields and represent a finite supply of water.
Under ideal conditions, PWSD can replenish underground aquifers in low-demand years. Known as aquifer storage recovery, this can provide seasonal water storage during the wet season and allow for quicker recovery during dry seasons.

Dam Structures

The dam will have a reinforced concrete low-level intake structure, including a trash rack to capture and remove heavy debris. A reinforced concrete gate tower will allow selective withdrawal from three elevations for delivery to PWSD water treatment facilities or back into Newlin Gulch.

The service spillway is a reinforced concrete impact basin at the downstream end combined with the outlet works. A 78-in.-diameter reinforced pipe will dissipate the service spillway and large stream releases before entering Newlin Gulch. It can safely carry large inflow runoff like a 100-year flood.

An excavated channel around the left abutment of the dam forms the auxiliary spillway and is capable of withstanding the 100-year flood.

When filled, Rueter-Hess will meet the area's long-term water needs while providing 2,000 acres of open space and recreational use for area residents. Still under development, the recreation plans call for nonmotorized boats, fishing and soft trails surrounding the park.

The decision to go with nonmotorized boats was an easy one, "We have a water treatment plant directly below the dam," said Nikkel. "We can't have oil and gas from motorized boats getting into the water supply."

Construction of Phase II can begin when the U.S. Army Corps of Engineers approves the enlargement permit. PWSD anticipates completion of the entire Rueter-Hess project by 2009.

In 2010, 25 years after Frank Jaeger predicted water would become a scarce resource in Douglas County, water may start lapping at the shores of Rueter-Hess.

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