Restoring Roads, Protecting Streams: The Stenner Creek Watershed Enhancement Project

Tucked into the beautiful rolling hills above campus, Cal Poly’s Serrano and Peterson ranches are places long used by students, researchers, community members and the university’s beef operations cattle for recreation, land management research and learning, and grazing.

Access to these ranches was becoming difficult, until Cal Poly partnered with four other agencies to address access problems as well as other obstacles challenging the ranches’ operations.

Serrano Ranch, which is usually reached using Stenner Creek Road, is frequently visited by recreationists. Peterson Ranch, accessed via Poly Canyon Road just past the “architecture graveyard,” is mostly used by students. Both ranches offer a gateway to roads and trail networks within their boundaries and beyond that connect to public land owned by the city of San Luis Obispo and the U.S. Forest Service. These ranches provide important habitat for many fish, fungal and wildlife species. While these roads and trails have long-provided access to all, they now face significant maintenance issues.

Many of these roads were built decades ago, with undersized culverts, poor drainage and little consideration for long-term erosion. During storm events, these roads easily erode and deliver large amounts of sediment directly into creeks. The result is both an ecological issue, as fish habitat declines, and a management issue, as roads require frequent maintenance, cause access problems and pose safety hazards. 

The creeks that run through Serrano and Peterson ranches, Stenner Creek and its main tributary Brizzolara Creek, are critical habitat for federally threatened South-Central California Coast steelhead. These fish depend on cool, clean water and healthy streambed gravels for spawning and rearing. For decades, however, excessive fine sediment has impaired these habitats, filling deep pools that fish rely on for summer refuge, reducing oxygen flow through gravels and smothering eggs before they can hatch. A major source of this sediment is the road networks across the watershed.  

In response, a partnership between the Coastal San Luis Resource Conservation District (RCD), Cal Poly, Pacific Watershed Associates, the California Department of Conservation and the California Wildlife Conservation Board came together to implement solutions designed to last. The goal: to stormproof three miles of ranch roads and upgrade 20 stream crossings across the two ranches, reducing sediment delivery and ensuring safe, sustainable access. Together, these treatments are projected to prevent more than 4,000 cubic yards of sediment from entering Stenner Creek, the equivalent of hundreds of dump trucks of material.  

Construction on the project was limited from July to mid-October to protect water quality and sensitive habitats. Additionally, biological and tribal monitors, including representatives from the Salinan Tribe of San Luis Obispo and Monterey counties and yak titʸu titʸu yak tiłhini (ytt) Northern Chumash Tribe, were on site to ensure sensitive resources were protected during construction. 

The most visible upgrades include new culverts and stream crossings designed to mimic natural hydrology and handle high flows during major storm events. Unlike the older crossings that frequently plugged or washed out, these new designs are “storm-proofed,” meaning they allow natural sediment and water movement without eroding or sending debris downstream. 

Other improvements are subtler but just as transformative. Improved road drainage treatments, including rolling dips and reshaped road sections now guide rainwater off the road surface and into upland areas where it can infiltrate naturally. Instead of water rushing down rutted roads and funneling sediment into streams, these new features spread the flow out, providing small amounts of water in many places rather than a great deal of water in one place. The result: improved water quality, healthier steelhead habitat and more resilient ranch roads. 

By blending ecological restoration with practical land management, the Stenner Creek Watershed Enhancement Project leaves a lasting legacy, supporting both the people who use the land and the fish that depend on its waters. 

Read more stories in the Fall 2025 Newsletter