Introducing Halo Ranch

The restoration of Halo Ranch is a textbook example* of using historical ecological studies to inform the design. Historically, the dark green areas were wet meadow, and the light green were tidal marsh and sloughs. Restoring tidal marsh and seasonal wetlands at the Bank (blue outline), where they historically existed, will create diverse habitats that can extend through the Turnkey site (pink) to connect to the Petaluma Marsh across the river. *Petaluma Valley: Historical Hydrology and Ecology Study, March 2018, San Francisco Estuary Institute-Aquatic Science Center.

Halo Ranch Mitigation Bank, prior to the beginning of the restoration, following a long period of agricultural use.

RES designed this restoration to follow the State Water Resources Control Board’s requirements for siting mitigation banks in accordance with watershed plans. Restoring this mix of seasonally wet meadow, tidal marsh, stream, and riparian areas also meets the USFWS goals for creating “substantial areas of wide diversity of tidal marsh and associated habitats.”

The Petaluma Marsh, which abuts the Halo Ranch Turnkey Mitigation Site opportunity, is the largest remaining natural tidal brackish marsh in California. It is established habitat for the California Ridgeway’s rail (yellow) and the salt marsh harvest mouse (purple). Halo Ranch can extend that habitat in accordance with the USFWS recovery plan for the area: “Habitat connectivity will increase the potential for population and genetic exchange, especially for less mobile species such as the salt marsh harvest mouse. If fringing marshes are used to establish connectivity, they should be as deep (from shore to bay) as possible from inboard to outboard edge, and should have wide and well vegetated high tide refugial habitat, capable of accommodating sea level rise.”

As the USFWS plan calls out, “opportunities to restore upland ecotones and accommodate upper extremes of sea level rise exist…around the Petaluma Marsh.” The location of Halo Ranch, at the interface with rising terrain to the northeast, puts it into a strong position to create habitats resilient to even the worst-case sea level rises. This map from the Bay Conservation and Development Commission Adapting to Rising Tides study shows that Halo Ranch can accommodate worse case scenarios for sea level rise while still containing upland transitional habitats.

The first release of credits is expected in late 2023 for Halo Ranch Mitigation Bank, covering wetlands, stream and riparian mitigation needs. It is the only bank in the northern region of the San Francisco Bay estuary area that will offer these credits. Site tours are available for both the Halo Ranch Mitigation Bank and the Halo Ranch permittee-responsible mitigation (PRM) turnkey opportunity, which contains habitat for the salt marsh harvest mouse and California Ridgway’s rail. Photo credit: Drone image by California State Lands Commission