Thanks to a robust effort to improve the habitat of the steelhead trout, the close relative of the rainbow trout is on the rebound in San Pedro Creek after its population dropped to fewer than 200 in 2004.
Since the bulk of the work to repair the creek bed on either side of the Capistrano Avenue bridge was finished last winter, the population of “steelies” has blossomed to between 1,000 and 2,000 fish, said Scott Holmes, Pacifica’s Public Works director.
“Overall, the stream is starting to function pretty good from a fish standpoint,” Holmes said.
That was not the case in Sepetember 2005. Changes to the creek’s watershed — including concrete culverts that sped the water’s flow and urban development that fed more water into the creek — narrowed its channel and ultimately created a drop-off of 19 feet in the bed below the bridge.
The banks were beginning to collapse, threatening some nearby houses, and fish were having difficulty getting past the barrier despite the installation of several fish ladders. The fish travel upstream during spawning runs, and their offspring swim downstream to the ocean.
“It’s a classic example of how creeks respond to changes to their watershed,” said Jerry Davis, a geomorphologist and member of the San Pedro Creek Watershed Coalition.
Between September 2005 and November 2006, crews fixed the banks, put approximately 10,000 yards of dirt in the channel, built several pools and ripples for the fish, and planted large trees and put in large rocks to complete the Capistrano Fish Passage Project, Holmes said.
Now there isn’t a 19-foot hitch in the creek bed, and fish can get up and downstream in the graded creek.
The project, fueled heavily by grant funding, cost roughly $2.3 million, with Pacifica contributing less than $200,000, Holmes said.
“It’s really just a matter of the environmental ethic of the city,” Pacifica Mayor Pro Tem Jim Vreeland said. “It’s one of the few productive steelhead streams in the urban habitat in California.”
First listed as a threatened species in 1997, steelhead were reaffirmed as threatened at the beginning of this year.
Dave Highland, a fish habitat specialist with the California Department of Fish and Game, said steelhead was an “indicator species,” meaning that if an environment has a healthy population then that is a sign it has good water quality and habitat conditions.
“It’s an impressive thing when you have a stream running through a highly developed urban area like that,” Highland said of the thriving fish population.
San Mateo County’s steelhead runs appear in “fair shape” overall, although most struggle with the effects of urbanization, water diversions and flood control measures.
Creeks along the more rural south coast between Half Moon Bay and Santa Cruz have healthier populations than others, but they face the same problems — primarily water diversions for domestic or farming usage — seen in other creeks in the county, biologist Jonathan Ambrose of the National Marines Fisheries Service said. The service administers the federal Endangered Species Act for steelhead trout.
Ambrose rated Pescadero Creek as having a good steelhead run — the best in the county.
Because of the difficulty in determining fish populations due to budget constraints and other obstacles such as the variation in numbers between juvenile and adult fish, Ambrose said a general metric used by biologists is that a good run equals more than one juvenile fish per linear foot of stream. A fair run is between one-half and one juvenile fish per linear foot, and a poor run is less than one-half fish per linear foot.
The county’s southernmost creek, Gazos, is in “really good shape” and also has the
county’s only consistently maintained Coho salmon run, Ambrose said, adding that San Gregorio, Tunitas, San Pedro and San Francisquito creeks are all in fair shape.
Pilarcitos Creek, however, which runs through Half Moon Bay, is in “very poor shape,” primarily because “everyone’s taking water” from the watershed, including San Francisco and Half Moon Bay.
“Fish and water kind of go hand in hand,” Ambrose said. Dams in San Mateo Creek have created barriers to steelhead and left the creek in poor