Much of the upper Alameda Creek
watershed is protected public land or remote ranchlands. The Calaveras
Creek tributary draining Mount Hamilton is almost completely blocked to
anadromous fish by Calaveras Dam. Efforts are underway to aid steelhead
migration into upper Alameda Creek above Little Yosemite and the Alameda
Diversion Dam, eight miles below the headwaters of Alameda Creek.
Calaveras Dam Rebuild and Stream Flows
The San Francisco Public Utilities Commission began a project to replace the seismically challenged Calaveras Dam in the upper Alameda Creek watershed in 2011. The SFPUC has agreed to future dam and reservoir operations that will benefit restoration of threatened steelhead trout. The SFPUC will reduce water diversions and construct a fish ladder and fish screens on the Alameda Diversion Dam, and provide water flow releases from Calaveras Reservoir into Alameda Creek when construction is done in 2018. They will also improve screens in the reservoir to prevent juvenile trout from being diverted or trapped during water operations and initiate a management plan to monitor stream flows and improve habitat conditions, with the goal of restoring a self-sustaining steelhead population in the watershed.
After the dam is rebuilt, the SFPUC will provide year-round water releases into Alameda Creek from Calaveras Reservoir ranging from 5 to 12 cubic feet per second, depending on the time of year and water-year type (wet, normal or dry). Particularly important will be cold-water flow releases during summer months to improve water quality and rearing conditions for trout. The SFPUC will modify operation of the 32-foot diversion dam in upper Alameda Creek, reducing its water diversion capacity by more than 40 percent, closing the diversion gates for more of the year to allow unimpaired natural flow to continue downstream, and ensuring minimum flows of 30 cubic feet per second past the dam during winter and spring.
Alameda Diversion Dam Fish Passage
The SFPUC will construct a fish ladder around the Alameda Diversion Dam from 2016-2017 to help adult steelhead migrate into the headwaters of Alameda Creek, the best trout habitat in the watershed below major dams. The SFPUC will also install a fish screen on the diversion dam intake structure.
Little Yosemite Fish Passage
The SFPUC changes to operation of the upstream diversion dam will increase winter and early spring flows in upper Alameda Creek and improve fish passage conditions at Little Yosemite in wet years. The SFPUC has assessed potential natural barriers to future steelhead upstream migration in upper Alameda Creek, including through the boulder cascades at Little Yosemite. The SFPUC is proposing some physical modifications to the boulder field to assist steelhead migration into the upper reaches of Alameda Creek. In November 2014 the SFPUC proposed a Little Yosemite Fish Passage Project. Proposed fish passage measures included constructing concrete weirs shaped like natural boulders or bedrock in three strategically located water features, with select boulders cut or removed and some holes, or slots through large boulders, may be filled with concrete to stabilize landing pools at the tops of waterfalls along the fish migration path. Planning for this project was suspended in 2015 due to concerns over impacts to imperiled frogs in Little Yosemite.
Sunol Park Swim Dam Removals
Two small swim dams were removed from upper Alameda Creek in the Sunol Wilderness by the East Bay Regional Park District in 2001.
SFPUC Steelhead Trout Migration Studies
Since 2000, SFPUC biologists have been studying the migratory patterns of landlocked steelhead/rainbow trout spawning in tributaries to Calaveras and San Antonio reservoirs. The SFPUC has conducted fish trapping to study the upstream and downstream movements of the fish in tributary creeks to the reservoirs. The information gathered on timing of steelhead spawning runs, water flow required for juvenile smolt movement downstream, and population size and genetic makeup of reservoir trout will be useful for steelhead restoration projects proceeding in the lower watershed.