Chippy Creek Project

The Chippy Creek stream crossing on the Lanes Creek Cutoff Road was identified as a high priority for restoration by the U.S. Forest Service during their Upper Blackfoot Watershed Analysis. An undersized crossing was causing channel instability and loss of aquatic habitat. Nearly 700–1,000 ft of channel has been lost near the crossing. Caribou County identified this as the highest priority for replacement in the upper Blackfoot drainage. 

The Chippy Creek stream crossing structure replacement portion of this project was completed during the week of November 7, 2018. We replaced the existing undersized crossing consisting of 2 squash pipes (36ft long by 3 ½ft x 5 ½ft) with a concrete box culvert (15ft x 6ft) and add two floodplain culverts to handle a 100-year peak flow event. 
Bridge was installed in Nov. 2018, but the floodplain culverts remain as there was hopes of reusing the existing culverts for the floodplain culvert.  Corroded conditions of those culverts did not allow them to be salvaged and reused. We constructed a natural channel within the box and placed cobble-gravel substrate approximately one foot deep to form the channel bed. 


We also elevated and stabilized approximately 300 ft of channel downstream from the crossing when we installed the new structure. The remaining ~5,000 feet of stream channel work will be completed in 2019, including a total of 2,210 ft upstream from the structure and 3,118 ft downstream from the structure.


The cumulative benefits of the project include (1) improved fish passage, (2) reduced erosion, (3) flood mitigation and road protection, and (4) restored stream function and stability due to increased channel length and floodplain reconnection. The channel and floodplain elements also restore streamside vegetation and adjacent wetland complexes that were lost when the stream down-cut.

Before

After

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