Chatfield Reservoir

Background:

Chatfield Reservoir is a flood-control reservoir on the South Platte River owned and operated by the U.S. Army Corps of Engineers. It was built in response to the devastating floods of 1965 that caused millions of dollars of damage in Denver. The reservoir has the ability to store more than 300,000 acre-feet of flood waters from the South Platte River and Plum Creek. Denver Water can use about 27,400 acre-feet of space in Chatfield, and uses its own water rights to fill and maintain water in the reservoir. Pursuant to an agreement with the State of Colorado, Denver Water manages its water for municipal supply, while also maintaining water levels for recreation. The land at Chatfield is leased to the State of Colorado, which operates Chatfield State Park. Below are some common questions we receive concerning Chatfield:

• How does Denver Water use its storage space in Chatfield?
  Denver Water uses its space in Chatfield to capture bypass flows it releases from Strontia Springs Reservoir, located a few miles upstream of Chatfield. The bypass flows maintain the trout fishery in Waterton Canyon.
• How does Denver Water use its water in Chatfield?
  Denver Water uses its water in Chatfield primarily for exchange to Denver's upstream reservoirs. An exchange is a trade of water. Water is released from Chatfield to supply a senior agricultural water right downstream of Chatfield, in exchange for allowing Denver Water to divert a like amount of water at its upstream reservoirs that have junior water rights, such as Cheesman or Eleven Mile. Exchanges of water help fill Denver's upstream reservoirs, from which water can be delivered to Denver Water's treatment plants. Without exchange, Denver Water would miss opportunities to store more water in its upstream reservoirs. Denver Water also has a temporary pump installed in Chatfield that can access the top five feet of the reservoir. This water is pumped to Marston Reservoir. (Western Water Law)
• How low can Chatfield get?
  Denver's use of its water in Chatfield is governed by an agreement between Denver Water and the State of Colorado. In most years, the reservoir stays above elevation 5,426 feet until around Labor Day to maximize recreation. However, in a drought, Denver can lower the reservoir level to an elevation of 5,423 feet. During severe drought conditions, Denver may lower the reservoir below 5,423 feet. Recreation at Chatfield is impacted at elevations below 5,423 feet.
• What is the Chatfield Reservoir Reallocation project?
  The Army Corps of Engineers has determined that a 20,600 acre-foot portion of Chatfield’s storage space currently reserved for flood control can be used (reallocated) for municipal and agricultural water supply. If the reallocation receives final approval, the total amount of storage for uses other than flood control will be about 48,000 acre-feet, including Denver Water’s current space. A group of 15 water suppliers have agreed to divide amongst themselves the new storage space that would be made available if the Army Corps of Engineers decides the project is feasible and the environmental and recreational impacts can be mitigated. The Corps is now conducting a study of the impacts of storing additional water in the reservoir. They plan to issue an Environmental Impact Statement (EIS) and Record of Decision (ROD) late in 2008.
• What is Denver Water’s role in the Chatfield Reallocation Project?
  In the mid-1990s Denver Water began seeking solutions to help enhance stream flow in the South Platte River through Denver. Denver Water supports this project because the additional water stored in the reservoir for the users downstream of the metro area could be released from the reservoir in ways to benefit the stream flows and fisheries in the South Platte River through Denver.
• Will Denver Water get any of the water from the Reallocation project?
  Denver Water will not receive water from the reallocated storage space in Chatfield. Denver Water is working to fully utilize its existing storage space in Chatfield and is also pursuing other options for increasing water supplies for the future. Denver Water recognizes the need for new water supplies for the 15 suppliers, many of whom now rely on non-renewable groundwater, and is interested in these suppliers’ success in developing renewable water. Denver Water will still maintain its original storage pool of 27,400 acre-feet and will remain involved in the overall operation of Chatfield after the reallocation is completed.

Also on the Web:

State of Colorado – Colorado Water Conservation Board

State of Colorado-Colorado State Parks

US Army Corps of Engineers
    Corps Lake Gateway
    Chatfield Dam and Lake