Streambed Alteration Agreement Concerning an Unnamed Tributary to the San Luis Rey River

Streambed Alteration Agreement Concerning an Unnamed Tributary to the San Luis Rey River

The proposed project consists of altering the streambed to replace an existing culvert which has become undermined. The streambed consists of an unnamed tributary to the San Luis Rey River that flows from the hillsides north of the river, under State Route 76 and, except during high flows, terminates at an agricultural field between the highway and the river. Within the project limits, it consists of a channel only a few feet wide at the top of the banks and supports only weedy exotic species. Immediately adjacent to the project, there is riparian vegetation dominated by willows. Arroyo toads are known to occur in the vicinity of the project. The culvert is located under State Route 76, west of Rice Canyon Road, at Post Mile 18.57. The proposed project includes removal of the existing 0.6m corrugated steel pipe and replacement with a 1.2m reinforced concrete pipe. A headwall will be constructed 9m from the edge of pavement on the westbound side of SR-76 and a flared end 7m from edge of pavement on the eastbound side. The total area of streambed impact is 0.81 acre, consisting of .0064 acre of permanent impact and 0.75 of temporary impact.

San Diego