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| Blue River |
Summit County, Colorado |
Primary Project Type: Instream Restoration
Secondary Type: Instream Restoration |
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Pre-project habitat on the Blue River was limited during low-flow periods due to... |
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Primary Problem: Flow Alteration
Secondary Problem: Loss of Fish Habitat |
| Main Restoration Action(s): Channel reconstruction, Habitat enhancement |
| Native Fish Focus: N/A |
Is this project part of a watershed scale restoration? No
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| Project Dates: January 2003 to August 2003 |
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Initial Monitoring: 2001
Restoration Implementation: 1/2003 to 8/2003
Follow-up Monitoring: 2004 |
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Lead Agency:
Northwest Colorado Council of Governments (NWCCOG)
Town of Silverthorne
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| Project Location:
The project area is a 0.6-mile stretch of the highly visible and accessible Blue River from the base of Dillon Dam to just below the Interstate Highway 70 Bridge in Summit County, Colorado.
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Project Description:
The Blue River is a famed gold medal trout stream in the heart of the Central Colorado Rockies. Because of its reputation, it is a destination river for anglers from all over the world. The Blue River rises high on Hoosier Pass in the White River National Forest and flows northward approximately 60 miles to its confluence with the Colorado River near the town of Kremmling. In its course, it falls nearly 5,000 feet in elevation and flows through some of the most scenic, historic and recreationally utilized mountain terrain in Colorado. The Blue River also fills three reservoirs for thirsty Front Range communities and flows through the fastest growing region of Colorado, a region growing at twice the rate of the state of Colorado as a whole.
In 1963 the Dillon Dam was constructed on the Blue River just downstream of the confluences of the Snake River and Tenmile Creek in Summit County, Colorado. The dam, which is located west of the continental divide, is used for water supply with a significant amount of the water stored in the reservoir being diverted across the continental divide as part of Denver’s water system. Construction of the dam significantly altered the hydrology and sediment loads for the Blue River downstream of the dam. In general, the magnitudes of both peak flows and typical baseflows have been reduced. The river, which was accustomed to annual peak spring flows in the range of 1000 cubic feet per second now might go years between such large flows. Increased water demands in the future will only exacerbate this problem. From the latter part of 2001 through June of 2003, releases from the dam were maintained at approximately 50 cubic feet per second for 20 straight months.
In addition to the dam's impact on flows, the natural incoming sediment load has been significantly altered, with the source of all larger sediment completely cut off by the dam and fine sediment limited greatly. In response to these changes, the river had become over widened and stripped of fine-grained materials, deficient in pool habitat or cover, and characterized by shallow, low gradient riffle habitat. Consequently, there were food producing areas (riffles), but little available resting/security habitat (pools and runs), which resulted in a lower productivity stream with regards to sustainable trout biomass. |
| Project Goals: The goal of this project was to insure that the Blue River, below Dillon Reservoir, remains a high-quality destination river for anglers. This included restoring viable trout habitat and the natural aesthetics of the river. The goal was not to restore the river to pre-dam conditions, but to create a natural stream that functions within the new hydrologic regime. To do so required the river be rehabilitated in a manner that mitigates current and projected flow conditions and impacts of the dam, and provides a variety of high quality trout habitat and fishing opportunities. The wide and shallow river needed to be modified with a new stream width and profile, and optimized for trout habitat. |
Project Methods:
For the Blue River restoration work, the ecology of the system and specifically the biologic requirements for high-quality trout habitat dictated physical parameters of the flowing stream, such as habitat types and ranges of depths and velocities. Appropriate ranges for slopes, pool-riffle spacing, meander geometries, bottom width and bankfull channel widths were determined by analyses of the altered hydrologic regime and by geomorphologic evaluations. Streambed and bank stability were then evaluated based on fluvial hydraulic calculations and engineering requirements. These calculations provided valuable insight into the rock sizes required to maintain stability in this sediment deprived system and indicated stable channel cross sections within the riffle sections.
To create an optimal trout fishery (many large trout) a variety of specific habitat features are required. In general, optimal trout riverine habitat can be characterized by clear, cold water; a silt-free rocky substrate in riffle-run areas; an approximately 1:1 pool-to-riffle ratio, with areas of slow, deep water; well-vegetated stream banks; abundant instream cover; and relatively stable water flow, temperature regimes, and stream banks. Evaluations indicated that the primary limiting factors for trout habitat below the dam were average water depth and over-wintering pool habitat.
Project design focused on creating these features. Deep over-wintering pool habitat was one of the primary objectives, as low flows provide reduced-quality habitat during this critical phase of the life cycle. Additionally, well-oxygenated riffles (at appropriate depths and flow velocities) and glides were all included, to replicate natural conditions and provide the range of habitat typical of a healthy ecosystem. This combination of habitat types will increase the overall holding capacity of the stream and create a diverse fishing experience. The final design will provide the fisherman with a wide variety of fishing opportunities, including deep pools, rock features, riffles and glides/runs.
Click here for more information on methods used.
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Constructed conditions on the Blue River. The restoration work created a meander... |
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Constructed conditions on the Blue River. The creation of bars on alternating ri... |
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| Monitoring Data and Collection
Methods: Electrofishing surveys were conducted on the Blue River between 2001 and 2004.
Click here for the results of the surveys.
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Was this project effective
and how was this determined? The town of Silverthorne and Colorado Division of Wildlife conducted fish surveys within the project area and downstream. Although more years of surveys are necessary to be certain, preliminary results indicate that the project was successful in restoring the habitat and improving the fish populations.
In addition to direct fish counts, project success can be determined by qualitative observation of the restored reach immediately after completion, as well as 18 months thereafter. The restoration work was successful in that it resulted in a more appearance with a variety of new trout habitat present. Quality habitat prior to the project was limited to two pools in the 0.6-mile stretch, whereas now trout and anglers can be found throughout the entire length of the project area.
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(Before) Pre-project conditions on the Blue River. In areas the pre-project chan... |
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(After) Constructed conditions on the Blue River. The appropriate width and flow... |
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Confounding Effects/Additional
Information: The Blue River Restoration project was a collaborative effort involving representatives from several jurisdictions and agencies, including federal, state and local levels of government along with several non-profit organizations. The working committee was key to the success of this project. Once the group was able to define the common vision for the project, the committee members met regularly and worked together to keep the project moving forward. The town of Silverthorne served as the project coordinator for the Blue River restoration project. The NWCCOG Foundation served as the fiscal agent, project administrator and facilitator for the Building Bridges partnership. Trout Unlimited coordinated volunteers and focused on the fundraising efforts.
In November 2002, the National Forest Foundation’s (NFF) challenge grant launched the fundraising efforts for the Blue River restoration project and served as the catalyst that gave the project credibility and momentum. Between November 1, 2002 and November 1, 2003, the working committee raised $99,898 to match the National Forest Foundation’s $94,750 challenge grant. The design for the restoration project was finalized in May 2003; construction began in early July 2003 and was completed in less than eight weeks. The Blue River restoration project was completed on time and on budget, and serves as a model for successful multijurisdictional projects. |
| Project
Specs (all specs are estimates): |
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Overall Estimated Cost:
$194,648
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| For more information on this project
contact: |
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Bill Linfield, Public Works Director, Town of Silverthorne, Email: wlinfield@silverthorne.org
Troy Thompson, Ecological Resource Consultants, Inc., Email: troy@erccolorado.net
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| This information
was collected by: Kristin Keith |
| Project last updated on: 4/6/2007 |
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