Corps releases final Chatfield study

Critics say the proposal to increase storage capacity at Chatfield Reservoir could turn the park into a prairie and the South Platte River into a mud puddle. Proponents say it could be the solution to the region's ever-increasing water struggles. Photo by Jennifer Smith
Staff report
Posted

The public has until Sept. 3 to comment on the final Chatfield Reservoir reallocation study, which was released Aug. 2.

The U.S. Army Corps of Engineers has not changed its stance from the draft study. To meet the growing need for water in the metro area, it still recommends reallocating 20,600 acre-feet of water from flood control to usable storage. That would raise the water in the recreation area by 12 feet, covering more of the park with water and requiring reconfiguration of the marina and other amenities.

The Corps notes a study by the statewide Water Supply Initiative that estimates Colorado will need between 600,000 and 1 million acre-feet annually of additional municipal and industrial water by the year 2050.

“There is also a strong need for additional water supplies for the agricultural community in the South Platte Basin, as thousands of acres of previously irrigated land has not been farmed in recent years due to widespread irrigation well curtailments,” reads a Corps press release.

The final report outlines three other options but concludes this is the least costly and has the most local support. It says this option would provide $8.42 million annually in economic benefits, while still acknowledging there could be adverse effects on recreation and the environment that will be “mitigated to the most sustainable alternative to below a level of significance.”

Gwyn Jarrett, project manager, says the Corps worked extensively with groups like Sierra Club and Audubon Society.

“By working together, the (study) captures and reflects a balance of interests and ultimately proposes the recommended alternative,” she said.

The draft report, published in June 2012, received nearly 1,000 comments from the public. Last August, Littleton City Council added its support to the project, but with some reservations.

“While Littleton continues to support the Chatfield reallocation project, it is concerned that the (Corps) has not given sufficient consideration to the potential environmental impact that may result under the (plan),” they write. “Specifically, Littleton is concerned that the potential impacts to aquatic and riparian habitat immediately downstream of Chatfield in (South Platte Park) have not been adequately addressed.”

In the final version of the study, the Corps acknowledges downstream flows are a key uncertainty.

“While mitigation and modification plans have been developed … in coordination with resource agencies, there is still a level of concern that implementing a reallocation could lead to a somewhat different condition for which environmental mitigation or recreational facility modification has not been designed appropriately,” reads the study. It says the water providers are working closely with resource agencies on projects that could pick up where the mitigation efforts leave off.

A statement last summer listed 49 entities supporting the plan, including Denver Water and a host of smaller water districts, several upstream counties and towns, the South Metro Fire Rescue Authority, Shea Homes, some water conservation boards and environmental groups.

The Highlands Ranch Metro District also submitted a letter of support, and the Highlands Ranch Community Association joined them but added some reservations. It expressed concerns about damages to the environment and recreational amenities in its letter, but Chairman Scott Lemmon said he felt confident that these concerns were being addressed by the Corps.

“I think that the long-term water security for Highlands Ranch far outweighs the 500 acres (of recreational space affected), even though it is a concern,” said board member Brock Norris.

Following the Sept. 3 close of the public comment period, the Corps will submit the report to the assistant secretary of the Army for Civil Works for final approval.