Streambed Alteration Agreement concerning San Diego River

Streambed Alteration Agreement concerning San Diego River

The operator did alter the stream through the unauthorized discharge of fill as a result of a rock slide caused by blasting at the rock quarry above the river. The rock slide impacts are estimated at 0.35 acres of southern cottonwood-willow riparian forest, 0.2 acres unvegetated stream, and 0.25 acres of riparian scrub in a pre-existing mitigation site, for a total of 0.8 acres. The rock slide caused the diversion of the river's flow over Manhole #74 of the East Mission Gorge Trunk Sewer Line, owned and maintained by the City of San Diego, Metropolitan Wastewater Department. In order to avert a potenital sewage spill, the City of San Diego initiated an emergency repair consisting of the clearing of a temporary access road and placement of on-site rock around the manhole and across the secondary channel to redirect the river back into the main channel (SAA R5-2002-0316). Impacts associated with the City of San Diego's emergency repairs are considered temporary and consist of 0.09 acres of southern cottonwood-willowriparian forest, 0.3 acres of riparian scrub in a pre-existing mitigation site, and 0.04 acres of unvegetated stream, for a total of 0.43 acres. The operator proposes to further alter the stream to remove the unauthorized fill. The removal project involves the excavation fo the existing mined slope to create a 75-foot bench adjacent to the river, but above the level of the 100-year flood plain. Once the rock fall area is reached, the rock will be removed from the river with an excavator parked on the bench. The removal of the rock may result in up to 0.17 acres of additional temporary impact. Native riparian habitats found on site include: southern cottonwood-willow riparian forest, riparian scrub, mule fat scrub, freshwater marsh, and open water.

San Diego

San Diego