DESCRIPTION
Culvert 021(40077)(00103) is an existing 11' x 21.5' precast concrete box, located at
MP 0.103 on Logan Hill Road, on Berwick Creek. This culvert is under ownership of
Lewis County. It was calculated to be 0 percent passable due to a 4.07 percent slope.
This culvert was ranked 156th for replacement within the upper Chehalis Basin and 4th
for replacement within Lewis County. Replacement of this culvert is anticipated to
restore access to an additional 3.73 linear miles of potential habitat; 20,670 square
meters of rearing habitat and 6,036 square meters of spawning habitat. There is a total
of 4.94 miles of upstream habitat that will eventually be available for fish. A priority
index of 16.22 was generated for this culvert.
In addition to barrier removal this project proposes to design a stream realignment in
which 500 ft of stream which currently runs along the roadway will be moved into the
adjacent wetland. The new proposed alignment will provide a more natural crossing,
will remove 250 ft of bank armoring, and will include the addition of meanders,
floodplain terraces, riparian plantings (minimum 50 ft buffer), and large woody debris
to add habitat complexity.
Lewis County provided a design to replace an 11-ft wide bridge with a concrete floor that is 0 percent fish passable with a 60-ft long by 24-ft wide by 11-ft tall fish passable structure. Additional construction will include the regrade and realignment of approximately 620 feet of channel, placement of streambed within the culvert and channel regrade area and incorporation of a low flow notch, construction of meander bars within the culvert, construction of large woody debris features upstream and downstream of the proposed structure, construction of an overflow channel for the Armstrong Rd Ditch, regrading of roadway slopes to improve roadway safety, and planting of a riparian buffer. Replacement of this barrier with a fish passable structure will restore immediate year-round access to 0.0 linear miles of habitat, as there are partial barriers present downstream, and seasonal access to 6.12 linear miles of potential habitat; 26,641 square meters of rearing habitat and 8,389 square meters of spawning habitat for the Southwestern Washington ESU of coho salmon, and Southwest Washington DPS of winter steelhead trout as well as searun cutthroat and resident cutthroat trout (as per WDFW barrier form).
