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RESERVOIR OPERATIONAL PHILOSOPHY

The Parker Water and Sanitation District (District) is located in Douglas County, one of the fastest-growing counties along the Front Range, as well as in the entire nation. Rapid development has increased demand on the finite water supplies available in the county, and the District believes that water management of these limited resources is critical. Therefore, the District has adopted a long-range water planning strategy to manage the limited water resources to achieve optimal longevity for all of the available water resources by efficient water management.

The District will develop Rueter-Hess Reservoir as the central management tool for increasing the longevity of the District’s water resources. Rueter-Hess Reservoir can provide terminal storage for many water sources and can then be used to manage these water resources. For example, water sources include in-priority Cherry Creek surface water and ground water, effluent from the advanced wastewater treatment (AWT) process that is pumped by exchange from Cherry Creek and in-priority Newlin Gulch surface flows.

Rueter-Hess Reservoir Benefits
Rueter-Hess Reservoir is a management tool and capital asset to help ensure a long-term, reliable water supply.
  • Direct use for municipal water supplies.
  • Carryover storage for reliable yields in dry years.
  • Source for bedrock aquifer storage.

Management of these water resources by reservoir operations will include providing carryover storage to continue to provide yields in dry years, serving as a water supply for subsequent bedrock aquifer injection, providing a means to get an increased benefit from low-yielding Denver Basin aquifer wells which can be pumped solely to provide base load demands and exchanging AWT effluent during the wintertime months for Cherry Creek water, then using this water to satisfy peak summertime demands.

RESERVOIR SITE [ top ]

The Rueter-Hess Dam axis crosses the section line between Sections 30 and 31 of Township 6 South, Range 66 West, approximately three miles southwest of the downtown Parker, Colorado, area. The reservoir site is located on Newlin Gulch, a tributary drainage to Cherry Creek that encompasses approximately 20 square miles upstream of the proposed dam axis. As such, the proposed dam may provide some flood regulation function.

Based on data generated from the preliminary dam design, this reservoir site can accommodate an approximate 14,300 acre-foot (ac-ft) reservoir that will be used to meet the needs of the District. The District has currently purchased 1,882 acres which includes the dam axis, as well as most of the reservoir area. The District is planning to obtain additional acreage to complete the site acquisition for the dam.

Rueter-Hess Reservoir Water Sources
Rueter-Hess Reservoir water sources include:
  • In-priority Cherry Creek flows.
  • In-priority Cherry Creek alluvial ground water.
  • Advanced wastewater treatment effluent pumped by exchange.
  • Irrigation return flows.In-priority flow in Newlin Gulch.

In addition to obtaining a reservoir site capable of storing up to 14,300 ac-ft of water, the District also obtained all of the Denver Basin ground water beneath the lands that it has purchased. Given a final surface acreage of about 2,000 acres, the District will have acquired approximately 3,000 ac-ft of water that can be extracted annually from the four principal Denver Basin bedrock aquifers. Since there will be no demands associated with the ground water beneath these undeveloped parcels, this Denver Basin ground water will serve as a supplemental supply to the District’s water supply portfolio.

There are several ancillary facilities that will also be completed on the reservoir site and between the reservoir site and Cherry Creek to divert Cherry Creek flows into Rueter-Hess Reservoir. Since Rueter-Hess Reservoir will store raw water, a water treatment plant is planned near the northeast corner of the reservoir site. This water treatment plant will process raw water from the reservoir, and then deliver these potable supplies into the District’s distribution system.

Water will be delivered to Rueter-Hess Reservoir from Cherry Creek by a surface-water and a ground-water diversion system. The alluvial wells, diversion structures, pumps, and pipelines are described below as the points of diversion for the water rights adjudicated on Cherry Creek.

HISTORICAL RESERVOIR DEVELOPMENT STUDIES [ top ]

In 1985, John C. Halepaska and Associates, Inc. (JCHA), as the hydrologic consultant to the District, prepared a report which showed that the District would face a 3,000 ac-ft shortfall at ultimate development based on the then-current District master plan, and the District’s then-adjudicated water rights. That report set in motion a series of studies which has resulted in the development of Rueter-Hess Reservoir.

To evaluate how the District could overcome its water supply shortfall, JCHA did a subsequent study on various water supply alternatives. One of these alternatives was to build an upstream storage vessel on Cherry Creek that would capture in-priority Cherry Creek flows. This study identified three potential reservoir sites that could provide an average annual yield between 2,100 and 2,800 ac-ft/yr.

Once the District identified these three potential upstream reservoir sites, the District filed for water storage rights in Division 1 Water Court in Case No. 85CW448. This case sought the right to store water in any of the sites identified in the JCHA 1985 study.

Given the potential yields from upstream reservoirs on Cherry Creek, the District pursued additional studies of these reservoir sites through the Colorado Water Resources and Power Development Authority (Authority). This project was funded by the Authority, and Morrison-Knudsen Engineers conducted studies related to the economic and technical viability of upstream reservoirs on Cherry Creek, as well as other imported water supply options. This study was completed in 1987, and the site of the former Castlewood Canyon dam was the recommended alternative for an upstream Cherry Creek on-stream reservoir.

Based on the results of the Authority’s study, as well as subsequent studies by the District, it was determined by the District that the Castlewood Canyon site was the most favorable location for upstream water storage and, therefore, the two additional sites were dropped from the Water Court application in December 1991.

Since the Castlewood Canyon dam site is located within the Castlewood Canyon State Park, it was necessary to get Colorado Parks and Outdoor Recreation’s approval to build the dam at this site. Even though the District proposed to dedicate 2,200 ac of land as parks and open space to Castlewood Canyon State Park, the Colorado Parks and Outdoor Recreation Board chose not to cooperate with the District in obtaining the right to construct at the old Castlewood Dam site. The District’s right to acquire the site for a dam at Castlewood Canyon was denied by the Colorado Supreme Court in November 1993.

However, prior to this decision by the Supreme Court, in June 1993 the District filed a motion in Division 1 Water Court to add two alternate reservoir sites in case the Castlewood Canyon dam site was disapproved by the Colorado Supreme Court. These two alternate dam sites are Lake Gulch Reservoir, located on a tributary of Cherry Creek just upstream of Castlewood Canyon State Park, and Newlin Gulch Reservoir, the current site of Rueter-Hess Reservoir.

With the elimination of the Castlewood Canyon Dam site, the District has turned its attention to Rueter-Hess Reservoir, with Lake Gulch Reservoir being a potential future option for additional upstream storage. Rueter-Hess Reservoir is considered comparable in many ways to the old Castlewood Canyon dam site. In fact, in many cases, the Rueter-Hess Reservoir site is superior to the Castlewood Canyon dam site. While Rueter-Hess Reservoir has a larger surface area-to-volume ratio, creating the potential for more evaporation at the Rueter-Hess Reservoir site, and it is an off-stream reservoir that reduces the efficiency of the collection of in-priority flood flows, there are several distinct advantages to construction at the Rueter-Hess Dam and Reservoir site. These advantages include:

  1. Proximity to the District’s water supply facilities, which allows reservoir filling from District Cherry Creek water resources and for distribution directly to the District’s municipal water supply system.
  2. Fewer permitting issues, due to the off-stream nature of this reservoir.
  3. Proximity to the District’s treatment plants, which facilitates the use of AWT effluent that is pumped by exchange from Cherry Creek.
  4. Proximity to the District’s Denver Basin well fields, which allows the District to implement a conjunctive use plan.
  5. Regional support for this reservoir site, as evidenced by its recognition in the Front Range Water Forum final report.

The originally-estimated 3,000 ac-ft shortfall that the District would face in the future at ultimate development has been relieved, based on actions the District has taken since 1985, including conservation, water re-use, and the purchase of additional lands where there would be no water demand associated with the ground water beneath these undeveloped parcels. In addition, with the proposed development of Rueter-Hess Dam and Reservoir, the District is moving toward its objective of providing the District with renewable water supplies to lessen the demands on the Denver Basin aquifers. These renewable water supplies are being developed with in-basin Cherry Creek and Newlin Gulch water.

Water conservation methods instituted in 1986 have resulted in a 40 percent reduction in residential water use as of 1998. A tiered pricing schedule has assisted in this water conservation effort.

PRELIMINARY WORK COMPLETED AT RUETER-HESS [ top ]

The first step in the development of Rueter-Hess Dam and Reservoir was to obtain a Division 1 Water Court decree which allows the storage of water in this proposed facility. The District has completed this task in Case No. 85CW448. In the decree in Case No. 85CW448, the District is allowed to divert water from Cherry Creek from two separate aqueducts. Aqueduct No. 1 is envisioned to be a manifolded pipeline from Cherry Creek alluvial wells at a design capacity of 12 cubic feet per second (cfs). Aqueduct No. 2 is envisioned to be a diversion of Cherry Creek flows to a point where the water can be pumped into a pipeline at a capacity of up to 150 cfs to be delivered to the reservoir. The date of appropriation for this water right is March 20, 1985. Under this decree, the District can divert water from Cherry Creek into the off-stream Rueter-Hess Reservoir whenever its water right is in priority.

Rueter-Hess Reservoir Site Advantages

Advantages of the Rueter-Hess Reservoir dam site:
  • Proximity to District water supply facilities for reservoir storage and for direct distribution.
  • Proximity to District treatment plant for use of AWT effluent.
  • Proximity to District Denver Basin well fields for a conjunctive use plan.
  • Fewer permitting issues due to the off-stream nature of the reservoir.
  • Recognized by the Front Range Water Forum.

In addition to being able to store in-priority Cherry Creek flows, the District has also adjudicated an augmentation plan (Case No. 83CW348), which allows the District to (a) operate its other Cherry Creek water rights under their own priority, (b) re-use its Denver Basin aquifer water, and (c) operate an exchange essentially through the stream reach that is within the District’s boundaries. The augmentation plan allows the District a greater degree of flexibility for water that is available for storage in Rueter-Hess Reservoir.

Preliminary work has also been conducted at the dam and reservoir site relative to the geotechnical feasibility of the dam and a preliminary environmental assessment of the dam and reservoir area. Knight-Piesold (KP) conducted a preliminary geotechnical investigation for the proposed Rueter-Hess dam axis in 1994 that included the drilling of four boreholes along the proposed dam alignment to evaluate subsurface conditions. In 1996, KP conducted a follow-up subsurface exploration that included the drilling of an additional four exploratory boreholes along the abutment areas of the proposed dam alignment and the digging of 23 test pits in the reservoir basin and embankment footprint areas to gain additional knowledge about the near-surface soils and bedrock, in addition to obtaining a cursory material assessment.

The results of the KP studies that have been conducted to date indicate that there are no geotechnical factors that preclude the ability to build the desired structure based on the data available to date. Specific findings of these studies include:

  1. The proposed dam abutments contain some non-cemented sandstones and possibly some unconsolidated sand, as well as being underlain by hard to very hard, low-permeability claystone.
  2. The porous materials on the abutments may require some engineering treatment.
  3. The valley bottom contains significant quantities of porous sand and gravel, which likely will have to be removed from the dam footprint prior to construction.
  4. Areas outside of the valley bottom are underlain by silty to clayey sand and sandstone, which offer good embankment founding conditions.

Further geotechnical work will need to be done for a complete assessment of the Rueter-Hess Reservoir area, as well as the dam axis. However, these preliminary studies were used in developing initial cost estimates for the Rueter-Hess Dam.

Environmental baseline studies were initiated at the Rueter-Hess Reservoir site by Woodward Clyde Consultants (WCC) in 1998. These environmental baseline studies included an evaluation of cultural resources, paleontology, vegetation, and wildlife. A second study was also performed by WCC in the summer of 1999 to further evaluate threatened and endangered species. The results of the WCC environmental baseline studies indicate that there will be environmental issues associated with this site. However, none of the issues raised by WCC is considered to be a fatal flaw. The studies conducted by WCC have yielded the following preliminary conclusions:

There are some areas of moderate to high potential for cultural resources on the site (300 to 400 acres) which should be further studied.

  1. Few fossils were found on the site and all of the fossils that were found in the study area are common to the region, thereby not having a high research significance.
  2. No Federal threatened or endangered plant species (Ute Ladies’ Tresses Orchid or Colorado Butterfly Plant) occur within the study area.
  3. Two rare and sensitive plant species, and one sensitive plant association, were found on-site. Dislocation of these plants could require mitigation.
  4. Jurisdictional wetlands were identified within the reservoir areas.
  5. Potential habitat for the Prebles Meadow Jumping Mouse (PMJM) occurs within approximately 10.4 acres of the site. However, during trapping conducted in 1999, no PMJM were found.
  6. No other Federal- or state-listed threatened or endangered animal species are known to occur or potentially to occur on site.

The District has proceeded with the initiation of environmental permitting and further geotechnical engineering studies to get the project to the preliminary design phase by early 2000.
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