Alameda Creek () is a large perennial stream in the San Francisco Bay Area. The creek mainstem runs for from a lake northeast of Packard Ridge to the eastern shore of San Francisco Bay by way of Niles Canyon and a flood control channel. Along its course, Alameda Creek provides wildlife habitat, water supply, a conduit for flood waters, opportunities for recreation, and a host of aesthetic and environmental values. The creek and three major reservoirs in the watershed are used as water supply by the San Francisco Public Utilities Commission, Alameda County Water District and Zone 7 Water Agency. Within the watershed can be found some of the highest peaks (Mount Isabel and Mount Hamilton) and tallest waterfall (Murietta Falls) in the East Bay, over a dozen regional parks, and notable natural landmarks such as the cascades at Little Yosemite and the wildflower-strewn grasslands and oak savannahs of the Sunol Regional Wilderness.
After an absence of half a century, ocean-run steelhead trout are able to return to Alameda Creek to mingle with remnant rainbow trout populations. Completion of a series of dam removal and fish passage projects, along with improved stream flows for cold-water fish and planned habitat restoration, enable steelhead trout and Chinook salmon to access up to of spawning and rearing habitat in Alameda Creek and its tributaries. The first juvenile trout migrating downstream from the upper watershed through lower Alameda Creek toward San Francisco Bay was detected and documented in April 2023.
History Whereas other Bay Area streams flow down from, or around, mountain ranges, Alameda Creek is unique in that it cuts across the Diablo Range at Niles Canyon. To geologists this is evidence that it is an antecedent stream that existed prior to the rise of the East Bay hills about a million years ago. As the mountain range was lifted by tectonic forces, the creek kept pace by eroding the canyon, which continues to this day. The large alluvial fan under Fremont, Newark, and Union City which juts into San Francisco Bay is further evidence that this creek has been in place for a very long time.
Five Spanish expeditions led by Portolà, Ortega, Fages, Anza and Amador passed over Alameda Creek between 1769 and 1795. El Camino Viejo between Pleasanton and Mission Pass crossed it near Sunol. Mission San José, in Fremont, was dedicated in 1797. The Mission thrived for 49 years until the Mexican government's Secularization Order liquidated mission lands in 1834. Alameda Creek was the boundary of the mission lands and the Rancho Arroyo de la Alameda granted to Jose de Jesus Vallejo, who built a flour mill near the mouth of Niles Canyon. The mill and the importance of the canyon as a passage through the hills led to growth of Niles (which in 1956 became part of Fremont, California) in the 1850s. A favorable climate, excellent soils, and a fast-growing population helped agriculture to boom. Early roads led to landings where small ships would load grain and other foodstuffs for transport to market.
Alameda Creek is the most important stream in Alameda County, which was named after it. It was the boundary between Contra Costa and Santa Clara counties between 1850, when Contra Costa and Santa Clara counties were formed, to 1853, when Alameda County was carved from the two counties. The portion of Alameda County south of Alameda Creek is the only part of Alameda County that is not derived from Contra Costa County.
Completion of the Central Pacific Railroad through Niles Canyon in 1869 was essential to completion of First transcontinental railroad that terminated at Alameda Terminal and Oakland Long Wharf that same year. The Western Pacific was also routed through Niles Canyon, connecting Sacramento, California and San Jose, California in 1906.
The creek bed had once been used as a gravel quarry.Chen, E., McMahon, P., Shorno, A., By, F., Bautista, J., Goza, G., ... & Inn, S. D. (2012). Alameda County Water District, Engineering Department, Groundwater Resources Division. When the gravel pits were flooded by water purchased by the public for groundwater recharge of the Niles Cone, the gravel harvesters began to daily pump out enough water to meet the needs of 30,000 people down the creek into San Francisco Bay.Victor E. Gleason, Water Projects Go Underground, 5 Ecology L.Q. (1976) discussing Niles Sand & Gravel v. Alameda County Water Dist., 37 Cal. App. 3d 924, 112 Cal. Rptr. 846 (Ct. App. 1974). After the pumping was declared to be an illegal waste the Alameda County Water District acquired the quarry in 1975.
In May 2015, vandals damaged an inflatable dam across the creek in Fremont, releasing 50 million gallons (190 million litres) of drinking water into San Francisco Bay.
Alameda Creek watershed
After the Sacramento and San Joaquin Rivers, Alameda Creek is the largest watershed draining into San Francisco Bay, with a total watershed of . It contributes about 20% of the total drainage area for the South Bay. Two-thirds of the watershed is in Alameda County including the reach through the Sunol Valley, the rest is in Santa Clara County. The tributaries of Alameda creek include Arroyo de la Laguna, Arroyo Valle, San Antonio Creek and Calaveras Creek, whose main tributary is Arroyo Hondo. The watershed includes three man-made reservoirs: Lake Del Valle, San Antonio Reservoir and Calaveras Reservoir.
The Alameda Creek Watershed can be divided into six major reaches: Alameda Creek Flood Control Channel – the channelized, trapezoidal section extending from the Bay upstream to the Niles Canyon area Niles Canyon – the area above the flood control section to the confluence of the Alameda Creek mainstem and Arroyo de la Laguna Upper Alameda Creek (above the confluence with Arroyo de la Laguna) – the reach extending up the mainstem of Alameda Creek into the canyons of the Sunol-Ohlone Regional Wilderness Area and beyond Arroyo de la Laguna – the reach paralleling Interstate 680 upstream of the confluence with the mainstem Alameda Creek, including the Alamo Canal, to its source at the confluence of South San Ramon Creek and Arroyo Mocho Arroyo Valle – the reach extending from the confluence with Arroyo de la Laguna upstream through Shadow Cliffs Regional Park to Del Valle Regional Park Arroyo Mocho – the reach extending upstream from the confluence with Arroyo de la Laguna through the Livermore–Amador Valley and into unincorporated ranch and agricultural lands
A more comprehensive list inclusive of minor as well as major named tributaries includes (from top of mainstem heading downstream) Valpe Creek (right), Bear Gulch (right), Whitlock Creek (right), Calaveras Creek (left), Leyden Creek (left), Indian Joe Creek (right), Welch Creek (right), Haynes Gulch (left), Pirate Creek (left), San Antonio Creek (right), Arroyo de la Laguna (right), Stonybrook Canyon (right) and Dry Creek (right). Alameda Creek now runs through the man-made Alameda Creek flood channel near the Bay, the latter is parallel to and south of the old Alameda Creek channel. Ward Creek is a tributary to old Alameda Creek.
Ecology, past and present
Alameda Creek historically supported spawning runs of at least three salmonid species: steelhead (the anadromous form of the coastal rainbow trout Oncorhynchus mykiss irideus), coho salmon (Oncorhynchus kisutch) and Chinook salmon (Oncorhynchus tshawytscha).
Return of Steelhead and Salmon Alameda Creek is considered a potential 'anchor watershed' for steelhead, regionally significant for restoration of the threatened trout to the entire Bay Area, although by the late 1950s the California Department of Fish and Game decided the steelhead run was no longer viable due to numerous man-made barriers to fish runs. By the early 1970s the Army Corps of Engineers channeled and rip-rapped the lower of the creek. The last steelhead and coho salmon runs in the 20th century were seen in the lower creek in 1964, the latter confirmed by photographic records.
Confirmation that adult steelhead captured attempting to migrate into the Alameda Creek watershed, and the rainbow trout sampled in the upper watershed (trapped above complete migration barriers), were native fish associated with the federally threatened steelhead Central California Coast Evolutionarily Significant Unit spurred a major effort to restore this historically important steelhead stream by removing barriers to migration and improving habitat quality. Since steelhead in the Bay Area and California's Central Coast were listed as threatened under the Endangered Species Act in 1997, numerous organizations, including the Alameda Creek Alliance, and governmental agencies have cooperated on restoration projects to allow migratory fish from the Bay to reach spawning habitat in upper Alameda Creek, beginning in 1999. This coalition of agencies and organizations is called the Alameda Creek Fisheries Restoration Workgroup.
In 2009, the Alameda County Water District removed a rubber dam that blocked trout passage in the lower creek, adjacent to Quarry Lakes Regional Park. In June, 2010 environmentalists and water district officials celebrated the removal of a dam on Alameda Creek in Fremont, and the planned installation of fish ladders to allow salmonids to bypass two other dams on the lower creek. At the same time, PG&E worked to modify a cement barrier farther upstream in Sunol to help steelhead swim farther into the watershed, water officials said. Ground was broken on the first ladder the Alameda County Water District was building in April 2018, just west of the Mission Boulevard overcrossing in the Niles district of Fremont, allowing passage around a rubber dam. The second ladder, which was planned to start construction in 2019, is about a mile downstream at the concrete structure, called a weir. The two ladders were funded by nearly $10 million in grants from several agencies, including $5.36 million from the California Wildlife Conservation Board and $3 million from the California Natural Resources Agency. The goal was that when those projects were completed in 2021, steelhead would be able to migrate upstream to spawning habitats in the Sunol Valley for the first time in a half-century.
In April 2023, one juvenile steelhead was found in the creek. The following year, monitoring by the San Francisco Public Utilities Commission recorded 50 tagged steelhead making the migration up Alameda Creek to the San Francisco Bay.
By November 2025, Chinook salmon (Oncorhynchus tshawytscha) had also ascended mainstem Alameda Creek into and beyond Niles Canyon, for the first time in decades, thanks to removal of the above weirs and dams. At least one salmon was seen upstream mainstem Alameda Creek.
Other fish California's archaeological record has contributed to knowledge of the prehistoric distribution of fishes in Alameda Creek and its tributaries including Sacramento perch (Archoplites interruptus), Sacramento suckers (Catostomus occidentalis occidentalis), Tule perch (Hysterocarpus traskii), Hitches (Lavinia exilicauda), Hardheads (Mylopharodon conocephalus), Sacramento blackfish, and Sacramento pikeminnow (Ptychocheilus grandis). Recent physical evidence has proved that the southern limit of coastal Chinook salmon included the southernmost tributaries of South San Francisco Bay. Many of these fishes still occupy the creek.
In 2023, a likely new species of lamprey (Lampetra sp.) was discovered in Alameda Creek by mitochondrial DNA genetic testing.
The number of introduced exotic fishes continues to increase in Alameda Creek and other San Francisco Bay tributaries with man-made reservoirs. Exotic fish species such as the largemouth and smallmouth basses (Micropterus salmoides and Micropterus dolomieui) respectively, were introduced to Alameda Creek (and the Napa River) by Livingston Stone in 1874.
Beaver