Storing water supplies for the future

StorageWhether it be planning for retirement or saving for college, most long-term plans require a healthy savings account. Storing water for the future, for times of high usage and drought is an essential piece in the overall water puzzle. This ensures the Town will have enough water on an annual basis to maintain the quality of life to which our residents are accustomed now and in the future. Castle Rock Water is securing storage for water supplies in area reservoirs and in underground aquifers.


Castle Rock Water has secured most of the storage needed for the Town's future at an investment of approximately $46 million. This storage space is primarily in Rueter-Hess and Chatfield reservoirs and the Town's current share will meet the water demands of approximately 80,000 people for a year. Reservoirs will be filled with renewable water, replenished from rainfall and snow melt, and reusable water that is treated and released back to the surface streams.

Rueter Hess Reservoir

Rueter-Hess Reservoir was built in 2012 by Parker Water for regional drinking water storage. At full capacity, the reservoir will hold 72,000 acre-feet of water, of which the Town owns approximately 8,000 acre-feet. Castle Rock Water joined regional partners on this project including Parker Water and Sanitation District, Castle Pines North Metro District and the Stonegate Village Metropolitan District.

More financial resources will be needed to build the infrastructure to move the water from the Plum Creek basin to Rueter-Hess Reservoir and then to build treatment capacity at Parker’s RHR Water Purification Facility to get the treated water back to Castle Rock. Furthermore, excess supplies of WISE water can be stored in the reservoir.

While the primary purpose of the reservoir is to store and provide safe, clean drinking water, the Rueter-Hess Reservoir Recreation Authority is also exploring options for possible recreational amenities. For additional information on the reservoir, visit Parker Water and Sanitation District.

Chatfield Reallocation Project

The Chatfield Reallocation Storage Project is a partnership among eight water providers in the Denver metropolitan area and northeast Colorado. Its purpose is to expand Chatfield Reservoir from a flood control structure to include water storage for municipal, agricultural and environmental purposes. In 2014, the U.S. Army Corps of Engineers approved the project and construction began in 2017. The expansion provides an additional 20,600 acre-feet of storage capacity in Chatfield Reservoir and be one and a half times the size of Cherry Creek Reservoir. Castle Rock currently owns 719 acre-feet of storage capacity with the ability to store up to 2,000 acre-feet of water in ‘optioned’ space under an agreement with the Colorado Water Conservation Board.

The total project cost was $170 million and Castle Rock’s investment in the project to date has been $6 million.

Learn more about the Chatfield Reallocation project.

Castle Rock Reservoirs No. 1 and No. 2

Castle Rock Water has the goal to have a year’s worth of water in storage – roughly 3.5 billion gallons for current annual usage, or more than 5 billion gallons in the future. Adding a new storage reservoir near Sedalia and expanding the existing reservoir will help meet this goal. These two, restricted-access reservoirs will increase storage capacity by 1,100 acre-feet which will help Castle Rock Water accommodate daily high demands during summer months with renewable water and will act as an additional storage vessel when Castle Rock Water is able to divert excess surface water from Plum Creek. In the future, we will even be pumping back water from Chatfield into these reservoirs and then back to Town for treatment.

A groundbreaking for the $30 million project took place in May 2023 and commemorated the opportunity for collaboration with regional partners to maximize the use of renewable water in Douglas County. 

Aquifer Storage & Recovery

Aquifer Storage and Recovery illustrationWater from rainfall and snow melt percolates down through the soil and fractures in the rock formations and collects to form aquifers. Castle Rock Water utilizes water from three aquifers ranging from 1,000 to 2,000 feet beneath the Earth's surface. In the past, these aquifers have been the primary source of water for many South Metro communities.

The Town has modified several deep groundwater wells to pump treated water down into the aquifer. When the Town has excess renewable water, it can be treated and then stored in the aquifers through these wells. During times of need, this water can be pumped back up, re-treated and sent to our customers.

A major benefit of underground reservoirs is that water stored deep underground doesn't evaporate like supplies stored in conventional surface reservoirs nor is it exposed to surface pollution which in turn requires more extensive treatment.

Two ASR wells near the Ray Waterman Treatment Plant are also equipped with down-hole power generation turbines. These wells are some of the first in the nation to add the ability to generate power as water is pumped back down into the aquifer. This endeavor greatly reduces the energy costs required for well pumping and potentially will add electricity back to the grid.