Arroyo Mocho

Arroyo Mocho is a tributary of Arroyo de la Laguna, which joins Alameda Creek in Sunol. The headwaters of Arroyo Mocho are southeast of Livermore. Arroyo Mocho through the Mocho Gorge (along Mines Road) has been identified as suitable spawning and rearing habitat for steelhead trout. Arroyo Mocho was a historical migration route and habitat for steelhead trout.

Many small potential fish passage barriers have been identified in Arroyo Mocho between Arroyo las Positas in Pleasanton and the Mocho Gorge. The ACA and Friends Of The Arroyos are lobbying for fish passage at these barriers and connection of the Mocho Gorge habitat with the Bay.

Friends Of The Arroyos Power Point Presentation

Migratory Fish Report for the Arroyos

August 2007 - Granada Fish Barrier Removed from Arroyo Mocho in Livermore

In August of 2007 Zone 7 Water Agency and the Livermore valley School District removed a concrete crossing from Arroyo Mocho behind Granada High School. Removal of this potential fish passage barrier also allowed Zone 7 to restore a more natural stream bed in this reach and reduce trash in the creek.

Read the Zone 7 June 2007 press release about the planned Arroyo Mocho Crossing Removal and a flyer on the completed barrier removal.

2007 - Zone 7 Stream Management Plan

The Zone 7 Water Agency is planning for multiple fish passage projects in Arroyo Mocho, Arroyo del Valle, and Arroyo de la Laguna as part of their Stream Management Master Plan (SMMP) projects in Livermore and Pleasanton. The SMMP proposes about a dozen restoration and enhancement projects which will remove or modify fish passage barriers, restore natural stream meander, plant riparian vegetation or replace non-native vegetation with native plants, create wetlands and other habitat for sensitive species, and install educational kiosks. There is also a project proposed to construct a trail along Alameda Creek from the confluence of Arroyo de la Laguna over 2 miles downstream into Niles Canyon to Stonybrook Creek. Although there appear to be a few traditional flood control projects that involve hardening stream banks in already-altered stream reaches, most of the proposed flood protection and erosion control projects appear to be quite visionary and take environmental and habitat consideration into account.

Information about the SMMP can be found here on the Zone 7 web site.

The initial comments of the Alameda Creek Alliance on the SMMP can be found here.

Fall 2006 - Lower Arroyo de la Laguna Restoration

In 2006, multiple agencies completed an erosion control and streambank restoration project along a 1,000-foot section of lower Arroyo de la Laguna, about a half-mile south of the Verona Road bridge between Pleasanton and Sunol. Visit the Zone 7 web page on the restoration project and read the September 2006 press release about the project.

2004 - LLNL Bridge Replacement

Congratulations to Lawrence Livermore Lab! Lawrence Livermore National Laboratory completed the Arroyo Mocho Road Improvement and Anadromous Fish Passage Project, which involved removal of a cement stream crossing from Arroyo Mocho, in fall of 2004. LLNL removed the low flow cement crossing of Arroyo Mocho, the primary access to the LLNL’s Arroyo Mocho Pump Station. The crossing was 160 feet long and 40 to 80 feet wide, containing a pipe that delivers Hetch Hetchy water to LLNL. The crossing had eroded and was in danger of failure due to undermining by the stream, creating impassable conditions for steelhead trout. LLNL replaced the crossing with a freestanding bridge above the 100 year flood mark. Since Arroyo Mocho is relatively pristine, extreme care was taken by LLNL to preserve habitat and restore the natural flow characteristics of the stream. LLNL Wildlife Biologists successfully translocated hundreds of amphibians, reptiles, and fish out of harms way during the project..Once the bridge was in place, native plants previously collected and raised elsewhere were planted in the project area to complete restoration activities. The new bridge is located about 6 miles downstream of Mocho Falls, upstream of Mines Road.

2003 - Arroyo Mocho/Arroyo Las Positas Realignment and Fish Ladders

Congratulations to Zone 7 Water Agency! In 2003, Zone 7 constructed two fish ladders as part of a project that widened, realigned, and restored the confluence of Arroyo Mocho and Arroyo las Positas in Livermore. Zone 7 removed existing concrete fish passage barriers, added the ladders to steep sections of the creek, restored a more natural stream channel, planted native vegetation, and generally enhanced wildlife habitat in the project area. The ladders will allow steelhead trout to access spawning and rearing habitat in the Arroyo Mocho gorge when barriers in lower Alameda Creek are removed. Read the ACA's February 4, 2003 press release supporting the fish passage projects.

More photos of new Arroyo las Positas fish ladder

Photos of new Arroyo Mocho fish ladder

2003 - Arroyo Mocho Groundwater Recharge Project

The ACA and FOTA were able to change another project proposed by Zone 7 Water Agency that would have added a potential fish migration barrier to Arroyo Mocho. Zone 7 made modifications to a proposed rubber dam which will be used for groundwater recharge, including operational constraints and a fish screen to avoid impacting juvenile fish. Read the ACA February 2003 press release on the revised project.

Stanley Boulevard Weir

An abandoned railroad bridge crossing at Stanley Blvd. on Arroyo Mocho has a low weir which requires modification for fish passage. Friends Of The Arroyos has written a letter to Southern Pacific RR requesting action on this project.