Restoring Water, Wetlands, and Wildlife at Johnston Ranch

At Johnston Ranch on the San Mateo County coast, a new water project is restoring wetlands, improving habitat for wildlife, and helping local farms thrive. More than 20 years in the making, the project demonstrates how conservation and agriculture can work together to build a more resilient landscape.

The San Mateo County coast has a way of stopping you in your tracks. The fog-softened light, the fields rolling down towards the ocean, the smell of salt and soil mixed together. There’s nowhere quite like it in California. It’s also some of the most productive farmland in the state, where generations of farming families have grown strawberries, Brussels sprouts, and heirloom beans in conditions found nowhere else. Protecting that land, and the people and ecosystems that depend on it, is at the heart of POST’s work on the coast. 

This summer, crews broke ground at Johnston Ranch near Half Moon Bay on a project that’s been more than 20 years in the making. When the work is done, the landscape will include new ponds, restored wetlands, and new hope for farmland and wildlife alike. But the story behind it is deeper than infrastructure: this is what’s possible when people commit to a place for the long haul. 

How the Project Supports Steelhead Trout and Local Farms

In the late 1990s, steelhead trout gained protection under the Endangered Species Act, and dams on Arroyo Leon Creek were opened so the fish could pass. It was the right call for the creek, but it also significantly reduced the water storage that Coastside farmers had depended on for years. Finding a way to restore that supply without harming the creek became one of the defining challenges of conservation work in the area. 

Now, the San Mateo Resource Conservation District (RCD), in partnership with POST and Midpeninsula Regional Open Space District (Midpen), is expanding the existing stock pond to hold nearly 1.6 million gallons of water and adding a second reservoir that will store nearly 4.9 million gallons. Combined, that’s enough water to fill almost ten Olympic-sized swimming pools.

Unlike a traditional reservoir built by damming a creek, the new reservoir will collect water from winter storms and store it for use during the dry season. That stored water will irrigate 20 to 30 acres of row crops and support conservation grazing across several hundred acres of grasslands. By relying on stored rainwater instead of drawing from local creeks in summer, the project helps leave more water in the stream when fish need it most.

Wetland Restoration Benefits Farms, Fish, and Frogs

Beyond improving the water supply problem, the project will create lasting benefits across the property. Wetland and riparian habitats will be restored and expanded, chronic erosion issues will be repaired, and fields that have sat fallow in dry years will come back into production, growing food tended by farming families who have worked this land for generations. 

Protected species win too. California red-legged frogs breed in stock ponds like the one crews are expanding here, and better pond habitat means more of this precious species. Steelhead trout, which swim up Arroyo Leon Creek from the ocean to spawn, will benefit from protected summer flows and improved creek conditions. 

It’s a genuine win-win, the kind that only comes together after years of careful planning, relationship-building, and refusing to treat farming and conservation as opposing forces. 

Why POST Stayed Involved Beyond Ownership

In 2024, Midpen purchased 644 acres of Johnston Ranch from POST, incorporating the land into Miramontes Ridge Open Space Preserve. POST retained the surrounding 224 acres of farmland, which we’re working to sell to a private farmer with a conservation easement that permanently protects it from development. 

POST had been working toward a water solution at Johnston Ranch for years before the sale, and our commitment continued after the ownership changed hands. Protecting land isn’t a transaction. It’s an ongoing relationship with the landscape, with the people who work it, and with the partners who share the vision. 

That’s why POST is contributing to this project alongside the RCD and Midpen, made possible in part by a Department of Water Resources grant secured by the RCD. The work we started here belongs to all of us, and we’re proud to see it through. 

Worth the Wait

When construction wraps up, the expanded pond and new reservoir will be ready to capture the season’s first rains, and the fields, the frogs, and the fish will all be better for it. 

Conservation wins like this one take time to unfold. We’re grateful to our partners at the RCD and Midpen, and to the farming and ranching families at Johnston Ranch who have been part of this effort from the start.