Enhancing Waterways with Wood for Wildlife
Published December 4, 2025
In and along San Gregorio Creek, ten newly installed pieces of large wood settle in to perform their intended function — increasing habitat complexity in the creek and creating a healthier environment for native fish species. These installations mark the completion of a habitat enhancement effort in Midpen’s La Honda Creek Open Space Preserve, done in partnership with the San Mateo Resource Conservation District.
Across forested landscapes, wood has historically played a critical role in shaping the physical features and ecology of streams. Native fish across California’s forested watersheds have evolved in streams shaped by large wood from old growth forests. Many watersheds across Midpen lands, including San Gregorio, have less large wood available than in the past due to loss of old growth forests and in-stream wood removal.
Inspired by successful projects in the Pacific Northwest and elsewhere in central California, this large wood restoration project aims to increase habitat complexity in San Gregorio Creek for wildlife, including federally threatened steelhead trout and federally endangered coho salmon.
The wood installations may appear natural, but they’re highly engineered and strategically placed. Over time, wood structures create habitat within and alongside the creek, providing refuge for native fish species at every stage of their life cycle.
These new wood structures will help create deep pools where young fish live and hide across the seasons. They also sort sediment during high flows, creating gravel bed streams that serve as spawning grounds for adult fish. Wood structures provide cover for fish from predators in the summer and from high flows in the winter and play host to aquatic insects that serve as a food source for many species, including California red-legged frogs.
The project, funded in part by Measure AA, builds upon similar work completed at the site nearly a decade ago. In 2016, Midpen installed 13 wood structures in San Gregorio Creek, in partnership with the San Mateo Resource Conservation District and California Department of Fish and Wildlife. Monitoring the site post-installation showed that the large wood created new habitat features in the creek and enhanced forage and refuge areas for native fish.
The effects of habitat enhancement efforts like these have the potential to support native fish recovery throughout the watershed. Much of the open space land that Midpen cares for and is actively working to restore is within the headwaters of important watersheds for steelhead trout and coho salmon. In the San Gregorio Creek watershed,
Midpen’s stewardship actions positively impact the health of waterways from upstream tributaries within the Santa Cruz Mountains to downstream reaches that flow to the ocean.