SCH Number 2025010259

Project Info

Title

Sunol Valley Passage Project

Description

Currently in Sunol Valley, a concrete erosion control mat (Er-Con mat) protecting a 36-inch pipeline, L303, owned and operated by Pacific Gas and Electric Company (PG&E), blocks upstream and downstream fish passage on mainstem Alameda Creek between the San Antonio Creek confluence and Calaveras Dam. The Er-Con mat is approximately 200 feet long, 70 feet wide, totaling .03 acres. The project is centrally focused on removal of the Er-con mat which will restore fish passage upon completion. The existing L303 pipe crossing Alameda Creek is operating in an effective and safe manner and the intent of this project is solely to restore ecological function to benefit fish and riparian habitat in upper Alameda Creek. Pipeline L-303 will be replaced with a new pipeline buried about 18 feet below the existing Alameda Creek grade to eliminate any need for an erosion control structure in the creek bed that limits fish migration and ecological function. The new pipeline will be located approximately 114 feet north of the existing one to allow for an open trench with shallow side slopes to account for soil stability during the construction excavation. The new pipeline will be connected to the existing pipeline outside of the creek banks, on both the east and west sides, at the same locations that the old line was cut out. The project will also regrade the Alameda Creek channel several hundred feet upstream and downstream of the pipeline crossing. No changes to hydrology or flooding regimes will result from the restoration activities, except for a slight reduction in the flood elevations and a reduction in the amount of erosion that otherwise would have occurred due to the 7-foot drop after Er-Con Mat removal. Sediments upstream of the fish passage barrier are not contaminated, and sediment currently passes over the Er-Con Mat in large flow events. The project phases would include fish and exclusion bypass; pipeline burial; regrading; and revegetation.Alameda Creek is an essential watershed for Central California Coast steelhead distinct population segment (Oncorhynchus mykiss; CCC steelhead; DPS), a federally threatened species (NMFS 2016) and may have the highest steelhead restoration potential of any stream in the Bay Area, being the largest local tributary to San Francisco Bay and given the extensive suitable upstream habitat now available to migratory fish. The NMFS recovery plan lists the upper portion of Alameda Creek as having a moderate to high Intrinsic Potential for Steelhead (NMFS 2016) and being Essential habitat for species recovery.Removal of the Er-Con mat will allow steelhead and potentially Chinook salmon and lamprey to access approximately 20 additional miles of spawning habitat in Alameda Creek and its tributaries. It is critical that these native fishes including steelhead have the opportunity to migrate unimpeded upstream or downstream as streamflows and conditions change throughout the year to access perennial habitat with cool water, food, cover, and sufficient spawning and rearing habitat. This is critical for recovery of steelhead in a changing climate where cool perennial streamflow and spawning gravel lie at higher elevations upstream of the project site.

1 documents in project