By Paul Jones, February 2019
The main trail in San Pedro Valley County Park is the Weiler Ranch trail, which runs parallel to San Pedro Creek for about 3/4 of a mile until it crosses over the creek affording a good look down at the stream. From long ago until 2001, the trail crossing consisted of a 6-foot diameter culvert about 25 feet long that was topped by soil and other waste material the farmer dumped to get the farm road level with the field. Over time, the Creek developed a “scour pool” on the downstream end of the culvert, making it almost impossible for adult steelhead to migrate past the barrier.
In 2001, the San Pedro Creek Watershed Coalition, working with San Mateo County Parks, County Maintenance Division, the City of Pacifica and volunteers, took to removing the old crossing and replacing it with a free-spanning bridge. The culvert was removed and we laid back the banks to match the upstream and downstream contours, installed rock weirs to control the stream, and used “bio-engineering” to stabilize the banks. This involved planting willows and alders to supplement the coir blankets that held in the soil until native plants could re-colonize the site. A 45-foot long bridge was anchored down, providing a great view down into San Pedro Creek and a refreshing place to take a break on a warm day’s hike.
December 1-3 of that year produced a whopping 8″ of rain and we were really worried about the site. But the good news is that it held up. Later that month, Dr. Jim Mackay, retired professor from San Francisco State University, sent an email telling me he just watched an adult pair of steelhead spawning in the large pool right under the bridge. Success!
This past Martin Luther King holiday, a similar sight was to be had as visitors made recordings of an adult, estimated to be 24″ long, prospecting in the same pool below the bridge before swimming off downstream. The San Pedro Creek continues to be a steelhead supporting stream, despite the pollution and habitat losses associated with development in Linda Mar. But given half a chance, these formidable fish will find a way to persist. The middle fork of San Pedro Creek is the most productive area for adults and rearing habitat, though fish can be found throughout the main stem and in the South Fork, also in San Pedro Valley County Park.
Paul Jones is a founding member of the San Pedro Creek Watershed Coalition, has been active in open space issues in Pacifica for years, and recently retired from the US EPA where he worked in wetland and stream protection programs for 27 years.