Little Browns Creek Migration Barrier Removal Project


Project Location:  Little Browns Creek is a tributary to Weaver Creek, a major tributary to the Trinity River below Lewiston Dam. The project is located in Section 28 of T34N R9W MDBM and is accessible by taking Highway 3 north out of Weaverville from Highway 299 for approximately 6 miles and turning left at Roundy Road (Trinity County Road #232). The project site is located just before the intersection of Roundy Road and North Roundy Road.Little Browns Creek culverts, pre-project

Link to the location of the remediated barrier in the CDFW Map Viewer (BIOS):

Passage Assessment Database ID: 705975

Project Description:  The purpose of this project was to provide for full passage of all life stages of coho salmon and steelhead to the natural limits of anadromy in Little Browns Creek by removing the three culverts at the Roundy Road Crossing of the creek that were a complete barrier. Additional objectives included eliminating the potential for 1,400 cubic yards of accumulated sediment to deliver to the downstream reaches of the creek and connected downstream watersheds, including the Trinity River; decreasing the potential for upstream headcutting; improving the flow capacity of crossing at Roundy Road; and, restoring natural stream function upstream of the crossing.
Pre-project conditions/barriers/challenges/background:  The old culvert structures did not allow for the passage of bedload and debris
associated with the high flows in Little Browns Creek and flooding at the site, as well as upstream sediment accumulation, was a common occurrence during winter storm events.
Project actions/deliverables: The three culverts were removed and replaced with a 30-foot long concrete cast-in-place bridge, implementing a full stream simulation design through the road crossing.

Little Browns Creek, post-project
Fish benefits/ecological value:  Provide full passage for all life stages of coho salmon and steelhead.
Other benefits: The full stream simulation design complies with the NMFS Guidelines for Salmonid Passage at Stream Crossings (September 2001), allowing for the100-year flood flows and associated bedload and debris to pass safely through the replacement structures. This treatment has prevented future culvert failures, reduced maintenance costs associated with storm flows and culvert plugging, and eliminated the potential for delivery of approximately 2,000 cubic yards of sediment into the downstream reaches of Little Browns and Weaver Creeks as well as the Trinity River.

Amount of habitat made available as a result of project implementation:  3 miles.
Habitat quality and type characterization:  Excellent quality spawning and rearing habitat for coho salmon and steelhead exists both below and above the project site.
Project partners:  5 Counties Salmonid Conservation Program, State Coastal Conservancy, California Department of Fish and Wildlife, Trinity County Department of Transportation, US Fish and Wildlife Service, NOAA, Trinity River Basin Fish and Wildlife Restoration Program
Project cost:  $507,003
Project start date:  2004
Project end date:  2008
Monitoring and evaluation:

  • Photo Monitoring: A photo-monitoring program to determine the project’s effectiveness was developed and is being continually implemented. Photo documentation of pre-project conditions including water turbidity downstream before, during, and after late fall and early winter rains was performed. Photo monitoring during construction and post-project monitoring activities has also occurred.
  • Longitudinal Profile/Thalweg Monitoring: The pre-project longitudinal and thalweg surveys used for designing the bridge and channel were completed in 2004 and entered into AutoCAD. Another pre-project longitudinal profile was taken starting from about 920 feet upstream of the project to 141 feet below the project (total length of 1,061 feet). Four cross-sections were also measured. A post-project profile was taken again immediately following project construction. The third profile will be taken in April/May 2008, and again after the second and third winters (April/May 2009 and 2010). Post-project surveys of the same areas were conducted immediately following construction and again at a future date in response to storm flows and channel adjustments.
  • Biological Monitoring: Spawning and presence/absence surveys will be conducted at the project site. The initial survey data consists of USFS and 5C Migration Barrier Inventory data collected prior to the project. The culverts were assessed as complete barriers to both adult coho and steelhead and juveniles of all age classes during the Trinity County barrier inventory. There is no available presence/absence data for this system upstream of Roundy Road and neither juveniles nor adults have ever been recorded since the culverts were installed. The first post-project spawning survey occurred in the spring of 2008 on about five miles of stream system. The start of the survey was the end of Little Browns Creek Road (about 4 miles upstream of the LBC confluence with Weaver Creek). The 4-mile section is half BLM property and half private property and wsa not initially surveyed. Surveys continued in the fall and winter through 2010; the results were reported in NOAA Open Rivers Grant (project partner) reports.

Did the project make a difference, and if so, how?

  • Stream length treated/assessed/made more accessible (distance in feet): ~15,840 feet
  • Instream habitat structures installed (number): 3 sections of 36-inch diameter, 12-foot long Incense cedar logs
  • Road length treated/assessed (distance in miles): 0.25 miles (North Roundy Road)
  • Stream crossings treated (number): 1
  • Sediment prevented from entering the stream (volume in cubic yards): 2,000 cubic yards
  • Trees planted (number): 25 Douglas-for trees & 274 rooted willow/cottonwood cuttings for a total of 299 trees planted
  • Area planted/preserved/assessed (area in acres): 0.32 acres total (area planted along the riparian zone, the detour and North Roundy Road)

For more information on the project, read the final report.