Spread Creek Dam to be Removed

Spread Creek dam is slated to be removed
to reconnect about 50 miles of native trout habitat

August 27, 2010
Superintendent Mary Gibson Scott is pleased to announce that Grand Teton National Park, in partnership with Trout Unlimited (TU), will begin a project to remove the Spread Creek dam—a water diversion structure located on a tributary of the Upper Snake River that flows from the Bridger-Teton National Forest into the east boundary of the park. The project will reconnect approximately 50 miles of critical trout habitat along Spread Creek and allow for the natural movement of native cutthroat trout and other non-game fish that historically migrated through this waterway to spawn. This project involves the removal of the dam, installation of natural-design and fish-friendly rock weirs, and the restoration of stream channel contours and vegetation.

The Spread Creek diversion structure is managed by Grand Teton, but located on Bridger-Teton forest land. The National Park Service and Wyoming Game and Fish Department (WG&F) identified the dam as a priority for restoration activities because Spread Creek provides habitat for the Snake River fine-spotted cutthroat trout—a state and federally recognized sensitive species. For more than 40 years, the existing Spread Creek diversion dam has caused a year-round barrier to fish migration because it spans the width of the creek and blocks tributary spawning and rearing habitat for native fish such as cutthroat trout, mountain suckers and whitefish.

Grand Teton will work in partnership with TU, a nonprofit 501(c) (3) corporation dedicated to protecting, reconnecting, restoring and sustaining native trout habitat. TU’s Wyoming Water Project is securing the funding for the project and will oversee and conduct restoration activities, including the removal of the existing diversion structure, construction of a water delivery system, and restoration of the natural stream channel. Grand Teton staff and TU are working closely with stakeholder groups such as the WG&F, Bridger-Teton, and Triangle X and Moosehead ranches who are historic water users along with Grand Teton National Park.

This project involves removal of the dam by mechanical means. Workers will bury a portion of the old concrete edifice to help support a new irrigation infrastructure. In place of the dam, three rock weirs will be installed to maintain water level at a new headgate that will divert irrigation water to authorized users in the park. The weirs are designed to allow for native fish to either pass over or through the structures to access historic spawning and rearing areas. After the dam is removed and the rock weirs are in place, the Spread Creek channel will be reconstructed to establish its natural hydrology, which has been interrupted for decades. Restoration of the channel downstream of the rock weirs will reflect the natural elevation and contour of the streambed and encourage native re-vegetation.

“This is an historic step toward correcting a long-term disruption to fish migration and an important action for restoring Spread Creek’s hydrology,” said Superintendent Mary Gibson Scott. “We appreciate and applaud the work of Trout Unlimited and their funding partners in making this milestone project possible. We also appreciate the cooperation we’ve received from historic water users, Bridger-Teton National Forest staff and the Wyoming Game and Fish Department as we launch this project to improve critical fish habitat outside and inside Grand Teton National Park.”