Several years of assessment of the potential human demand and the actual need for flow augmentation for the endangered fish resulted in the 2006 enlargement to create more human supply and 5,000 acre-feet of storage for endangered fish flow management. Construction of the enlargement took two years and was completed in 2006 at a total project cost of $31 million dollars.
The enlargement required raising the height of the dam 25 feet raising the normal pool 20 feet creating 11,956 acre feet of new storage; new outlet works and tower with an outlet capacity of 550 cfs, and a new labyrinth weir and spillway capable of conveying discharges up to 25,000 cfs.
Uniquely, the Upper Colorado River Recovery Program invested $13.6 million, including $6.5 million from the State of Colorado Native Species Conservation Fund, in storage in Elkhead Reservoir to assist with flow management on the Yampa River. Unlike other Colorado River tributaries, the Yampa River has no federal or other large storage to reprogram for flow enhancement in the effort to recover these endangered fish.
The Recovery Program is designed to protect the Colorado pikeminnow, humpback chub, the boneytail and the razorback sucker in the Upper Colorado River Basin. The other 6,750 AF of the enlargement is allocated for future water needs in the Yampa River Basin and funded by $17.3 million from the Colorado River District, which is partially financed through a construction loan with the Colorado Water Conservation Board (CWCB). Two-thousand acre feet of this pool is currently leased to the Recovery Program for 20 years. The varied ownership and uses of water stored in Elkhead Reservoir creates some unique management issues, none more important than the competition between the resident sport fish within the reservoir and the endangered fish downstream.
A major component of the planning and design of the enlargement had to clearly address containment of the resident sport fish within Elkhead Reservoir. Resident sport fish in Elkhead consist primarily of warm-water species like northern pike and smallmouth bass; however, the DOW does stock rainbow trout as a put and take species. Competition from non-native species has adverse impacts on the recruitment and restoration of the endangered fish population. Pike and bass are known to prey on the endangered fish in the river.
The recreational resource value of sport fishing in the area was deemed a valuable asset to the public and needed to be maintained. In order to maintain these seemingly opposing management goals, a means of containment for nonnative species in the reservoir is included. The Elkhead fish separation project was born and an advisory committee formed to evaluate the most effective means to achieve fish separation.
In the end a combination of the labyrinth weir design and stainless steel fish screens on the outlet works were recommended. The fish screens are equipped with a self cleaning pneumatic blower system to help prevent debris from clogging the screens. The construction of the fish screens alone added $750, 000 in costs to the enlargement which was funded by the Recovery Program in addition to the purchase price of the storage. Nonnative sport fish are not the only management concerns at Elkhead Reservoir.
The project also benefited from a $1.5 million CWCB mitigation grant which was shared by the River District and the Recovery Program to meet the other mitigation requirements such as wetlands impacts.
Like most reservoirs in the state Elkhead Reservoir has instituted a boat inspection program to help prevent the spread of the invasive zebra and quagga mussels. An infestation of these mussels could prove problematic to the effectiveness of the fish screens and severely limit outflow capacity and raise operating costs for divers to scrape the screens.
Operating and maintaining reservoirs in today’s environmental climate requires cooperation and sometimes complex solutions in order to achieve management goals. In the world of reservoirs Elkhead may seem small in size but is large in management complexity. Next time you find yourself in northwest Colorado looking to do some boating or fishing be sure to visit Elkhead Reservoir.
In 1990 the City of Craig entered into a transfer agreement with the Colorado Parks and Wildlife and acquired the dam and reservoir. Currently after the 2006 enlargement, maintenance and operation is shared between the City of Craig and the Colorado River District, and the recreation facilities are managed by Colorado Parks and Wildlife.
Former capacity: 13,800 acre-feet
Enlarged capacity: 25,550 acre-feet
Cost to enlarge: $31 million
Old dam elevation: 6,378 feet
New dam elevation: 6,403 feet
For the latest information Elkhead Reservoir, contact River District Deputy Chief Engineer Ray Tenney at 970.945.8522, ext. 220, or email firstname.lastname@example.org.
Elkhead Hydrology Figures
Yampa Valley Water Demand Study
Feasibility Evaluation of Non-Native Fish Control Structures
Fish Separation Preliminary Design Report
Your Water, Your Fish, Your Future
by Melanie Fischer, Information and Education Coordinator
Colorado River Recovery Program
The Colorado River District has been an active partner in the Upper Colorado River Endangered Fish Recovery Program since its inception and supports this successful program. Water that supports your family also supports healthy rivers for plants, birds, and fish, including four endangered native fishes: bonytail, Colorado pikeminnow, humpback chub and razorback sucker.
Found only in the Colorado River Basin, these four ancient species evolved over millions of years to live in a desert river system. These “dinosaurs of the river” are part of our western heritage and a critical part of overall river ecology. Conserving these fish enhances the overall health of your rivers.
The Recovery Program is a public and private partnership that works together to bring these fish back from the brink of extinction. This program provides streamlined Endangered Species Act compliance so that water development can proceed as fish populations recover. Water development is important to Colorado’s citizens, but it can change river flows and temperature, and block fish migration. The Recovery Program uses science and partnerships to manage those threats and support fish recovery in a way that minimizes impacts to water users. The River District is proud to be a partner in the recovery of these unique fish. We and other Colorado River water users provide water releases from reservoirs on the western slope. This water benefits Colorado River fish in times of low water, fish spawning, or other habitat needs.
The biggest remaining obstacle to recovering the endangered fish is large numbers of predatory nonnative fish that now live in the river. The three most damaging nonnative species are smallmouth bass, northern pike, and walleye. These fish compete with and prey on the endangered fish. Colorado Parks and Wildlife (CPW) and the U.S. Fish and Wildlife Service manually remove these invasive, non-compatible fish from the river, but it’s not enough. We also must eliminate illegal introduction of nonnative fish (people moving fish from reservoirs to the river) and nonnative fish escaping into the river from reservoir spills during spring runoff. The River District led the Elkhead Reservoir Spillway Fish Barrier Net Project, completed in 2016. The Recovery Program and its partners have installed nets at other reservoir outlets on the western slope to prevent fish escapement. Nets are a temporary measure while CPW replaces non-compatible sport fisheries with compatible fish like trout, kokanee salmon, wiper, largemouth bass, tiger muskie (sterile hybrid) and triploid walleye (sterile fish). CPW also offers fishing tournaments at Elkhead Reservoir east of Craig and Ridgway Reservoir south of Montrose. Tournament anglers help remove non-compatible smallmouth bass, northern pike, and walleye. You can help recover these unique endangered fish by participating in CPW’s fishing tournaments and by reporting illegal fish stocking.
Your efforts to help native fish contribute to a healthy river system for the future. This means better water for all of us. For more information about the endangered fishes of the Colorado River, visit coloradoriverrecovery.org. To learn more about CPW’s fishing regulations on the Colorado River, Click Here
Thanks to the leadership of the Colorado River District, preservation of fishing opportunities at Elkhead Reservoir near Craig, Colorado and critical efforts in support of protecting endangered fish downstream from the reservoir were accomplished with the installation of a spillway barrier net.
The Elkhead Reservoir spillway barrier net is an important component of the Recovery Program plan directly benefiting the native fish species in the Yampa River, including the razorback sucker, Colorado pikeminnow, humpback chub and bonytail by increasing survival rates.