Alameda Creek Alliance


Northern Watershed Arroyos

The highly urbanized Livermore-Amador Valley is drained by Arroyo de la Laguna and its tributaries Arroyo del Valle and Arroyo Mocho. Most of the arroyos have intermittent stream flow and have been channelized and straightened. Arroyo Valle runoff is impounded by Lake del Valle, while the upper Arroyo Mocho gorge is unregulated and relatively pristine.

Zone 7 Stream Management Plan
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 for flood protection and stream restoration in Livermore and Pleasanton. The plan 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. 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.

Living Arroyos Program
Living Arroyos is a joint program of Zone 7 Water Agency, City of Livermore and the Urban Creeks Council to restore the streams of the Livermore-Amador Valley, to return functional, beneficial native habitats to the Valley's riparian zones.

Zone 7 Environmental and Hydrologic Analysis
Zone 7 has begun an environmental and hydrologic analysis of instream flow, critical passage, potential habitat utilization and opportunities for stream and riparian habitat enhancements for fish and amphibians in the arroyos, to be completed by 2014.

Castlewood Drop Structure Removal

In 2013 Zone 7 Water Agency removed a failing in-stream concrete structure located in Arroyo de la Laguna in Pleasanton, at the Castlewood Country Club pedestrian crossing. The obsolete structure was removed because it was a flooding and public safety hazard, but it was also a potentially significant migration barrier for fish. See photos of the structure removal. Before: aerial view - side view - from downstream. After: aerial view - from downstream. Read Zone 7's final report on the structure's removal.

Lower Arroyo de la Laguna Stream Stabilization
In 2011 and 2012 the Alameda County Resource Conservation District, Natural Resources Conservation Service and other agencies completed two stream bank stabilization and restoration projects along a highly eroding reach of lower Arroyo de la Laguna in Pleasanton, at Verona Bridge. These projects are intended to minimize streambank erosion and demonstrate inexpensive and environmentally friendly stream stabilization and bioengineering restoration methods, such as a log crib walls, boulder placement and re-vegetation with native plants. They help improve fish passage and habitat quality for western pond turtles and migratory birds. See the Alameda County RCD web page on the Arroyo de la Laguna restoration projects.

Granada Fish Barrier Removal
In 2007 Zone 7 Water Agency and Livermore Valley School District removed a concrete crossing from Arroyo Mocho that was a potential fish passage barrier. This restored a more natural stream bed in the reach behind Granada High School and reduced trash in the creek. Read a Zone 7 flyer on the completed project.

Lawrence Livermore Lab Stream Crossing
In 2004 Lawrence Livermore National Laboratory removed a 160-foot long and 80-foot wide low flow cement stream crossing from Arroyo Mocho at LLNL’s Arroyo Mocho Pump Station. The crossing was undermined by stream erosion and was in danger of failure, creating potential fish passage problems. LLNL replaced the crossing with a freestanding bridge above the 100 year flood mark. Since Arroyo Mocho is relatively pristine, extreme care was taken to preserve habitat and restore the natural flow characteristics of the stream. LLNL wildlife biologists successfully moved hundreds of amphibians, reptiles and fish out of harms way during the project, and the project area was restored with native plants.

Arroyo Mocho Groundwater Recharge Project
In 2003 the Alameda Creek Alliance and Friends of the Arroyos 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.

Arroyo Mocho/Arroyo Las Positas Realignment and Fish Ladders
In 2003 Zone 7 Water Agency constructed two fish ladders as part of a project to widen, realign and restore the confluence of Arroyo Mocho and Arroyo Las Positas in Livermore. Zone 7 removed existing concrete fish passage barriers, added fish ladders to steep sections of the creek, restored a more natural stream channel and planted native vegetation to enhance fish and wildlife habitat. The ladders will allow steelhead trout the potential to access spawning and rearing habitat in the Arroyo Mocho gorge when barriers in lower Alameda Creek are removed. View photos of Arroyo Las Positas fish ladder and the Arroyo Mocho fish ladder.