by Ali Freedlund
May 31, 2002

Culverts can present big problem for migrating salmon. Culverts are chutes under roadways that salmon have to negotiate to arrive at the lovemaking climax of their life. These chutes often channel the water too fast, at too steep a slope for many fish to get through to the other side. In addition, water exiting the culvert can create an inaccessible jump pool into the culvert (too high a jump or too shallow a pool).

Humboldt County Public Works, with funding from the California Department of Fish and Game (DFG), undertook a study to prioritize culverts that cross county roads on the basis of improvement to fish passage. This study was completed in 2000. Beginning last summer, with further DFG funding, the county began to actually replace, upgrade and /or redesign culverts that were given highest priority. By the end of this year they will have completed the top 10 prioritized culvert replacements in the county. One culvert in the Mattole, on Clear Creek in the Lower Mattole, was replaced last summer out of eight in the whole county. It was replaced with an arch which allows the stream to flow under the road with a natural bottom.

This summer three of five county culvert replacement projects are in the Mattole. One on East Anderson Creek in the Upper Mattole along Whitethorn Road will be replaced with a 16 foot arch similar to Clear Creek. Transportation will be rerouted in an appropriate place. The two additional culvert jobs are both in Petrolia, and are both named Mill Creek! Both will be upgraded to bridges. That’s Mill Creek on Lighthouse Road and East Mill Creek on Conklin Creek Road. These projects are scheduled to take place in late August. Conklin Creek traffic will be rerouted across the river in the same place as the reroute for the Clear Creek culvert upgrade last fall. Lighthouse Road traffic will have a temporary bridge across Mill Creek while they work on the permanent bridge. Culvert jobs should be completed by the end of September.

Currently, the County is in the application process for next year. If accepted, five additional culvert jobs will then take place in the Mattole: Stanley Creek, Saunders Creek, Indian Creek, Stansberry Creek and Bear Creek. Stansberry Creek presents the biggest design challenge. Bear Creek will probably remain in its current course but be replaced with a box culvert to allow the streambed to naturalize through the crossing.

As an outcome of all these efforts, salmon will have an easier time getting to their spawning gravels to make more salmon for the future. For more information about the current projects, contact Chris Whitworth at the Humboldt County Department of Public Works, 445-7377.



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Table of Contents for Mattole Restoration Newsletter, Issue 18 - Summer/Fall 2002