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Trinity County Project News
CONNER CREEK#1 - Conner Creek Road Migration Barrier Removal Project (Construction Scheduled for August-October 2011) An existing box culvert with a jump at the outlet and high velocity flows was replaced with a bridge to accommodate 100-year flows and fish migration. The upper 41% of the watershed burned in a 2008 fire, increasing risk of sediments. An upstream partial barrier will be removed in 2012.
"Before" view of Conner Creek at Conner Creek Road
The 5C Counties use a variety of techniques to improve fish passage, storm flow, bedload and debris passage at county road crossings. Engineering staff strive to design projects that balance site and right-of-way constraints with traffic, safety, biologic, geologic/hydraulic, costs and other factors. This approach has resulted in more than 25 separate design approaches.
"After" image of same location-new bridge accomodates storm flows and natural creekbed beneath bridge allows for fish passage
Read more about this project in the Trinity Journal newspaper:
CHINA GULCH PHASE 2A - China Gulch Road- (Completed) Ten road erosion sites within a 1-mile stretch of China Gulch Road in Trinity County were addressed during 2010. The picture (below, left) shows an upslope, partially-gutted debris slide and culvert inlet before project implementation. Large rock slope protection (RSP) was installed upstream of the stream crossing. A larger culvert was placed at the crossing and a critical dip was installed across the road (below, right). Final grading and rocking are pending.
 
TRINITY RIVER - Dutch Creek Road Sediment Reduction Project – Phase 2 Construction Begins in 2012. Two proposed treatment sites on Dutch Creek are related to fill failures (below, left) and slides (below, right). This project will include upgrading existing culverts and installing additional ones to dewater ditch segments at the base of active slides. Upslope portions of the project area were burned in 2008.
 
 Fisheries Monitoring and Project Design - Sidney Gulch A habitat improvement project for Sidney Gulch is in the planning stages. Sidney Gulch, a tributary to Weaver Creek, is identified as a priority watershed for coho recovery under the CA Coho Recovery Strategy because of year-over-year Coho populations. Sidney Gulch is an integral part of the Weaver Creek fish population matrix. There is potential to increase channel and habitat complexity to support larger populations of Coho, steelhead, and other aquatic species as well as increasing the stream’s carrying capacity.
 Sidney Gulch Migration Barrier Removal Project at Weaver Bally Loop Road The existing structure is a circular corrugated metal pipe 7-foot diameter and 60-feet long set at 4.91%. The culvert is undersized for 100-year flows and estimated to overtop during a 20-year storm flow. When first installed, engineers evaluated the stream and determined the system was aggrading. They subsequently determined that the culvert did not have to be embedded, assuming that it would embed itself naturally. This determination proved to be wrong and the outlet of the culvert remains above grade and has downcut significantly. This new project would improve fish passage and reduce sediment/bedload transport at the stream crossing by replacing one undersized culvert structure with a larger box culvert.
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Image of Chinook Fry at top of page courtesy of USFWS & Dan Cox.
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