The Cottonwood Creek Daylighting Project in Boise, Idaho, creates a unique opportunity to place habitat restoration in an urban setting. Cottonwood Creek is currently buried in a flume in Julia Davis Park. Once daylighted, Cottonwood Creek will provide fisheries habitat and endless educational and recreational opportunities in a high visibility location in a popular city park across the street from a major university and research center. The project is expected to:

• Reestablish connectivity and a confluence zone between Cottonwood Creek and the Boise River;
• Create spawning and rearing habitat for rainbow and brown trout and whitefish;
• Increase flood capacity of Cottonwood Creek, currently constrained by the size of the culvert;
• Serve as the third phase of what is shaping up as one of the most significant trout habitat restoration initiatives sponsored by Trout Unlimited in an urban setting;
• Provide educational opportunities as part of TU's efforts in the Boise metro area for the general public, K-12 school children, undergraduate, graduate students, and communicate the importance of small and intermittent streams.

The Ted Trueblood Chapter of Trout Unlimited has been awarded a grant from the national Trout Unlimited Embrace A Stream program that provides seed money to cover costs of developing a plan for daylighting Cottonwood Creek. We believe the early money can leverage the planning and partnership building into on-the-ground action.

The Rotary Club of Boise is a partner on this project. The goal is to complete the restoration work so that it can be dedicated as part of the Rotary Club International centennial in February 2005. Trout Unlimited is very excited to be working with the Rotary Club on this project because of the Rotary track record as an important service club in the Boise area. A window of opportunity exists for Trout Unlimited to be the catalyst behind this project because a supplemental water source will soon become available in the area. Daylighting Cottonwood Creek is identified as a project in the City of Boise's Boise River Management and Master Plan. The Boise Parks and Recreation Board has also included daylighting Cottonwood Creek in its updated master plan for Julia Davis Park, adopted in 2002.

Three large Federal storage projects located in the basin prevent movement of suitable spawning gravel from the headwater streams to the Boise River through town and thus inhibit natural processes of streambed movement of larger and smaller gravel, channel formation, and other ecological processes of a river environment. Smaller diversion and hydroelectric dams along the Lower Boise River trap riverbed gravels thus rendering the lower Boise River through the city dominated by cobble-sized rock.

The Cottonwood Creek Daylighting Project addresses the conservation need for more off-channel habitat for fish and wildlife along the lower Boise River. Habitat studies show the river lacks suitable spawning and rearing habitat for salmonid fishes. Restoring side channels and off-channel habitat is recommended.

To get a closer look, we borrowed the concept drawings for the University Place (formerly Idaho Place) development and imposed a red squiggly line for where a daylighted Cottonwood Creek would be located within Julia Davis Park.

Cottonwood Creek is a tributary to the Boise River and the final mile or so of stream is confined to a concrete flume in downtown Boise, Idaho. The last 440 ft of the flume lies buried underneath Julia Davis Park and can be "daylighted" to restore a natural stream in a public park. Once daylighted, Cottonwood Creek will provide aquatic and riparian habitat off the main channel of the Boise River and will be a project with high visibility to the public because of its location in downtown Boise. The project would affect about four acres in the park.

This aerial photo includes an illustration of the location of the existing buried flume (dashed yellow lines). The flume follows a direction running along a cul-de-sac in the east end of the park. The cul-de-sac is slated for removal, making for a logical location for a daylighted stream. Elevation contours for the park are also shown. In the upper right hand corner of the photo, just east of Broadway Avenue, the overflow for the flume is visible. The intersection in the photo experiences around 30,000 cars per day. Broadway Ave. handles the north-south traffic while the five lane-wide Myrtle Street directs traffic to the southeast. Whether or not they realize it, thousands of people will see Cottonwood Creek be restored to a stream.

Project Summary

This project will restore and reconnect the last 450 ft of Cottonwood Creek where it enters the Boise River in Julia Davis Park in downtown Boise. The additional habitat will support trout spawning, rearing, and over-wintering fish habitat, all of which are limiting to the river fishery. Julia Davis Park is managed by the City of Boise. This project is designated as a priority project in the City of Boise's Boise River Management and Master Plan. Trout Unlimited participated on the Steering Committee that helped the city write this plan in 1999. This plan enhances the management of the Boise River Greenbelt, a nationally recognized river and parkland protection effort that was initiated over 30 years ago. Subsequently, the master plan for Julia Davis Park was adopted in 2002 and includes the daylighting project.

A window of opportunity exists for Trout Unlimited to be the catalyst behind this project. The University of Idaho has commenced construction of the Idaho Water Center phase of University Place, a higher education and research center in Boise. The University Place complex will be constructed north of Julia Davis Park. A planned underground parking structure is under construction on the site of the Idaho Water Center, and it will be necessary to pump groundwater on a fairly constant basis. Plans are to discharge the water into the Cottonwood Creek flume underneath Broadway Avenue. Trout Unlimited has discussed this project with the U of I and presented an option that includes daylighting Cottonwood Creek in conjunction with providing a less expensive location for the groundwater discharge from the Idaho Water Center. We believe that the daylighting project will actually save construction costs for the Idaho Place.

The Ted Trueblood Chapter expects that over time there will be additional partners involved in this project. In addition to the Rotary Club of Boise and Boise Parks and Recreation Department, we expect interest on the part of the University of Idaho, Boise State University, the US Forest Service, Idaho Department of Fish and Game and the Idaho Department of Water Resources.

Cottonwood Creek drains an 8,000 acre watershed of the Boise Front north and east of downtown Boise. At the point the creek meets the valley floor and the city, it is routed through a flume for about one mile in length to the Boise River. It is the final 450 ft of flume that appears feasible for a daylighting project underneath Julia Davis Park near the intersection of Broadway Avenue and Myrtle Street in downtown Boise because it is in a public park.

Flows in Cottonwood Creek generally range from less than 1 cfs to 40 cfs in a normal water year. This chart shows the recorded flows as measured at a USGS gage in Cottonwood Creek in the watershed above town. Click here to observe current flows.

Peak flow is in the early spring as the watershed is a low elevation area (highest elevation is less than 5,500 MSL). Recent watershed rehabilitation efforts and constructed floodwater retention settling ponds function to improve water quality and remove sediment from the stream prior to its being routed to the flume.

Both vegetation establishment and growth and aquatic conditions will be monitored. TU will seek the assistance and advice of Idaho Fish and Game for a proper monitoring plan for Cottonwood Creek. Boise Parks and Recreation will monitor the effects of the restoration project with potential involvement of graduate students from University of Idaho¹s Ecohydraulics Research Group.

Because of the high recreational use along the Greenbelt walking path in Julia Davis Park, there exists a tremendous educational opportunity for the general public. In addition to describing the project and its cooperators, signage will be used to educate the public about the importance of connectivity of tributaries with major streams, as well as riparian and wetland habitat.

Summary of Activities and Expected Outcomes

• Formalize partnerships with cooperators Rotary Club of Boise, City of Boise (both Boise Parks and Recreation and Public Works);
• Extend partnerships to University of Idaho, US Forest Service, Boise State University, Idaho Department of Fish and Game and Idaho Department of Water Resources;

  

• Develop Project Plan including comparison of current and desired conditions, identification of issues and constraints, estimates of materials and equipment, and proposed project schedule;
• Promote the proposed daylighting project in local media and with target audiences;
• Expected Outcome: Roughly 500 feet of daylighted stream (depends on meander wavelength). Channel will function as tributary to main river and support salmonid spawning and rearing habitat. Reconnecting a tributary to the Boise River, even 450 ft of what is often an intermittent stream, will also benefit the aquatic system by adding diversity to the river system, restoring the underlying processes of the confluence zone between a river and its tributary;
• Expected Outcome: Summer flow enhanced with groundwater source pumped from the developed properties north of Julia Davis Park. This summer water will help maintain Cottonwood Creek flows and enhance its fishery values.
• Expected Outcome: Increase public recognition of Trout Unlimited as a credible player in conservation issues and community based projects in southwest Idaho;
• Expected Outcome: Development of a living laboratory, where local biology students can monitor the colonization and ecological development of a real stream.

Questions or comments? tutedtrue@aol.com
Ted Trueblood Chapter of Trout Umlimited