Restoration

Mill Creek Erosion Control & Prevention

The existing road network includes at least 290 miles of roads. During the rainy season, many roads in the project area have the potential for catastrophic failure, which would destroy important salmon and trout spawning and rearing habitat. The road network must continue to be managed to reduce risk to native salmonids. In the longer-term, road removal reduces the cumulative potential for failure and related impacts to aquatic habitat and eliminates maintenance costs. Due to the annual heavy rainfall and high concentration of roads, the highest risk to aquatic life is due to erosion and the potential of high sediment loads from failures at road-stream crossings, in-sloped roads traversing steep terrain, and log landings.

There are 65 miles of high-risk roads and 180 stream crossings with a high risk of delivering sediment to streams and seriously impairing water quality and salmonid habitat. In Spring 2005, DPR completed a road inventory which increased these numbers to: 129 miles of high-risk roads, 350 critically unstable stream crossings, 210 landings and three instream barriers to prime spawning and rearing habitat.

The purpose of erosion control activities is to maintain and enhance water quality by reducing sediment contribution to priority wild salmon and trout streams by decommissioning and re-engineering selected road segments. 

Treatment of Roads: High priority road segments are treated to reduce the threat of catastrophic failure through a combination of decommissioning and re-engineering. Over the 3-year period, 25.8 miles of road will be removed; field crews will revegetate 106 road/stream crossing areas that have been decommissioned in Rock Creek and the East Fork of Mill Creek drainages; 74 landings will be stabilized, and 60 landslide sites stabilized. 

Storm Season Patrol: During the stormy season, field crews patrol the high-risk erosion sites, following routes and protocol defined by DPR for culvert clearing/cleaning, construction of diversion prevention ditches (to prevent catastrophic road failure if a culvert should become plugged), and making contact with equipment operators if larger problems are encountered. The Mill Creek Erosion Control Patrol Crew operates with four individuals from October 1 through April 30. 

Stream Crossing Repair/Improvements: Many of the existing culverts installed by the former landowner are undersized and not properly installed to withstand a 100-year storm event. These culverts are being replaced with improved high capacity culverts in order to prevent road failure and large-scale sediment deposits instream.