Long-Awaited Partnership Project Breaks Ground on the Coastside
Published June 4, 2026
Collecting water in the winter when it is abundant and storing it for agricultural use in the summer is simple in theory, but difficult in practice without the right infrastructure. This has been an ongoing challenge at Johnston Ranch near Half Moon Bay particularly since the late 1990s when the listing of steelhead trout under the endangered species act required that dams on Arroyo Leon Creek be opened for the fish, significantly reducing water storage for the farmer.
A new project is breaking ground this summer in Midpen’s Miramontes Ridge Open Space Preserve, led by the San Mateo Resource Conservation District (RCD). It will provide more reliable year-round water for conservation grazing in the preserve and row crops on the neighboring farm. Midpen’s unique mission on the San Mateo County coast, where agricultural roots run deep, includes supporting viable agriculture.
Rare native frogs and other wildlife will also benefit as the existing pond habitat they depend on is being expanded and improved. Fish will benefit from higher summer flows in Arroyo Leon Creek as the new off-stream storage replaces creek diversions during the summer irrigation season.
An existing human-made pond for livestock water will be expanded from one acre-foot—enough water to cover an acre of land one foot deep—to five acre-feet. Winter runoff will flow from the pond into a new reservoir that will store an additional 20 acre-feet of water for the row crops on adjacent land owned by the private, nonprofit Peninsula Open Space Trust (POST) and farmed by a local family.
“This project achieves conservation goals for California red-legged frogs and steelhead trout, provides new water storage for Midpen’s conservation grazing program and achieves an original goal of replacing the agricultural water supply that was lost because of the decommissioning of the dams,”said Midpen Senior Resource Management Specialist David Liefert.
Water is Life for Wildlife
Steelhead trout are a threatened fish that swim up Arroyo Leon Creek from the ocean to spawn and lay their eggs in the gravelly creek bed. The young fish stay in the creek up to three years before migrating back out to the ocean. The threatened California red-legged frog breeds in human-made ranch ponds, which commonly do double-duty on the Coastside both supporting agriculture and providing critical remaining habitat for native wildlife. The project includes changes to how water drains across the landscape to reduce sediment in the watershed that impairs fish habitat.
Increasing Local Food Production
When complete, the expanded pond and new reservoir are estimated to reliably support at least 20 acres of crop land and many more acres of conservation grazing. This means some surrounding agricultural fields that are currently fallow in dry years can be brought back into viable production for the long-term, increasing local food production and improving local agriculture’s resilience to drought.
Public-Private Partnerships
The Johnston Ranch property encompasses more than 800 acres of open space and working agricultural lands bordering the southern edge of the City of Half Moon Bay. Midpen, a public agency, finalized the purchase of 644 acres of the property from POST in 2024, and incorporated them into Miramontes Ridge Open Space Preserve.
This portion of the land includes rolling coastal grasslands with active cattle grazing, creek and stream corridors and the site of this project. Grazing by a local ranching family continues on the property under Midpen’s Conservation Grazing Program.
POST retained private ownership of the surrounding 224 acres of farmland and intends to sell it to a private farmer with a conservation easement permanently protecting it from development. Long before Midpen acquired the land and became involved in this project, other partners were leading the effort to rebalance the availability of water for both wildlife habitat and agriculture on the Coastside.
“POST and the RCD have worked for more than 20 years towards these multi-benefit, win-win projects where we can find ways for agriculture to be viable and creeks to be protected, and this project shows that,” said RCD Executive Director Kellyx Nelson.
In 2023, the RCD secured grant funding from the California Department of Water Resources to design and implement the project. Midpen is contributing a total of $2.8 million in Measure AA funds towards a portion of the design and construction costs.
“It’s really gratifying seeing this project come to fruition. It’s been a great partnership. We all bring different strengths and resources and perspectives,” Nelson said. “The project team considered different sites and design concepts, worked with the farmer to find something that really works for him and protects conservation values, and found a sweet-spot where there’s cost-benefit.”