The North Fork of Prosser Creek meanders across the Carpenter Valley. A fluvial geomorphic assessment/feasibility study of the creek was conducted to assess effects of a potential bridge structure.
Carpenter Valley extends several miles in an west-east direction. The width varies from about 100 yards to near 1/3 of a mile. The location of the stream has changed numerous time throughout geologic time. This is evidenced by the many oxbows and old channels on the meadow. Currently the channel is on the south side of the meadow impinging on steeper terraces. There were several locations of existing erosion downstream of the proposed bridge crossing on the inside of meander bends and these areas show a potential tendency toward meaner cutoffs. Several conditions existed for this bridge crossing: geomorphology, water quality concerns and environmental permit issues for not only the bridge crossing itself but for the entire roadway length to include traffic frequency and patterns.