On Tuesday, August 29th, members of the Pikes Peak chapter attended a site visit for stakeholders of the Eleven Mile Canyon Diversion Dam Removal project. Partners include the Coalition for the Upper South Platte, US Forest Service, Colorado Springs Utilities, Park County, Colorado Parks and Wildlife, and FlyWater, Inc.
The project is on track to completely remove the dam by the end of the year. All remaining work, including the parking lot, restrooms, trails, revegetation, and a new pay station, is scheduled for spring 2024.
The project follows several steps for removing the dam structure, which include:
Creating a channel around the diversion dam to route water during removal
Rerouting the river into the newly created channel
Removing and storing dry sediment behind the diversion dam to be used as fill later in the project
Demolishing the main diversion dam structure down to the original channel
Rerouting the river into the newly restored channel
The clear channel around the diversion dam has been created, and engineers are beginning to reroute the river. They have installed two bridges over the channel to transport heavy equipment to the original channel. A rock weir has been created below the dam to help contain any sediment, and a boom is set up across the channel to contain any accidental petroleum spill. In addition, a French drain has been created to capture seepage from the river and route it back into the channel below the dam via a notch cut in the dam.
The clear channel was designed to handle flows up to 300 cfs, but the current protocol calls for a maximum flow of 150 cfs in case of significant rain events. Additionally, sediment behind the dam is being tested for toxins and will continue to be tested as the dam is removed.
Before the diversion dam removal, USFS and CPW will perform a fish salvage near the dam. After removing the dam structure and restoring the original channel, the old parking lot will be revamped with new restrooms. An ADA trail with additional fishing access is also planned. The temporary clear channel and bridges will be removed, and all the disturbed areas will be restored and revegetated with willows and other native plants.
