Environmental Review Toolkit
Water, Wetlands, and Wildlife

Cactus Wren perched on cactus
Cactus Wren. (Caltrans)
cactus and wildflowers on hillside
(EDAW Inc.)

California Department of Transportation

California's South Bay Expressway Mitigation Program

Imagine a highway-construction project with more than 1,000 environmental commitments. That's the South Bay Expressway, SR 125 South--the last new freeway planned for San Diego County. The 10.8-mile alignment crosses through sensitive habitat for threatened and endangered species, known historic and cultural sites, community park areas, and established residential communities. The daunting commitments include everything from restoring habitat to mitigating noise and air pollution to protecting water quality to recovering cultural-resource data.

The California Department of Transportation (Caltrans) has spent approximately $20 million to acquire about 2,000 acres for ecological mitigation. Specific mitigation preserves were identified in close collaboration with resource agencies, local municipalities, and the region-wide Multiple Species Conservation Program. Caltrans' goal: to develop mitigation within a landscape context. To meet this goal, the sites were strategically selected to help fill large gaps in open preserve areas. A long-term habitat management plan was then prepared for each preserve and the Center for Natural Lands Management was hired to develop Property Analysis Record software.

The 202-acre Johnson Canyon Open Space Preserve is renowned for being the first habitat restoration designed specifically for the federal ESA-listed (endangered) Quino checkerspot butterfly. The preserve also safeguards sensitive species and their habitat, such as the federal ESA-listed (threatened) Otay tarplant, coastal sage scrub (habitat for coastal California gnatcatchers), maritime succulent scrub (habitat for coastal cactus wrens), and vernal pools (habitat for the San Diego fairy shrimp). The preserve will become part of the Otay Ranch Preserve--an 11,375-acre habitat conservation area. What's more, thanks to a partnership among Caltrans, U.S. Fish and Wildlife Service (USFWS), California Native Grassland Association, Jepson Herbarium, and other local organizations, the preserve can offer environmental-educational programs for the public.

Another mitigation preserve called Bonita Meadows, supports 104,500 individual Otay tarplants. The 200-acre preserve was established as a regional mitigation bank for Federal-aid and Caltrans transportation projects. Lake Jennings, another preserve, was purchased to mitigate losses to the coastal cactus wren and its habitat. The bird's habitat was destroyed by the 2003 Cedar Fire which burned 273,000 acres in San Diego County. Two years after the fire, cactus wrens were again nesting and producing fledglings, surrounded by 102 floral species--even sensitive species like small-flowered morning glories and San Diego sunflowers which had not been detected there before the fire. Lake Jennings has been so successful, the project team is collaborating with a local conservancy to incorporate the preserve into a watershed-based restoration and preservation effort along the San Diego River.

The South Bay Expressway Mitigation Program has involved many innovative adaptive-management strategies. Here are some examples:

  • The project team partnered with USFWS and the California Department of Fish and Game to acquire Quino and gnatcatcher habitat in a parcel known as San Ysidro. The parcel was slated for residential development but instead was purchased by Caltrans to protect the parcel's natural resources;

  • Caltrans partnered with the County of San Diego, the San Diego Association of Governments and USFWS to buy a site proposed for a 1,800-acre housing development and turn it into the Rancho San Diego Mitigation Bank, the first step in creating what is now the San Diego National Wildlife Refuge. The impetus and money for the bank were generated by the mitigation requirements of the expressway project;

  • Caltrans, FHWA and a private partner together set up the Rancho Jamul Wetland Mitigation Bank. Twenty credits will be purchased as soon as the bank is established, helping the banker to make a safe return on his investment.

Through multi-agency and multi-disciplinary collaboration, high-level science, and landscape-based approaches, the South Bay Expressway Mitigation Program is setting a higher standard for mitigation efforts within and beyond the San Diego region. Always under close scrutiny, the program has received much support from regulatory agencies and surrounding communities, and it has allowed Caltrans to move ahead on four large transportation projects in San Diego County.

For more information, contact Bruce April, bruce.april@dot.ca.gov

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