Environmental Review Toolkit
Water, Wetlands, and Wildlife

California: Elkhorn Slough Early Mitigation Partnership

Poster/map showing protected lands under the Elkhorn Slough Early Mitigation agreement
Protected lands under the Elkhorn Slough Early Mitigation agreement
Aquatic birds in Elkhorn Slough
Aquatic birds in Elkhorn Slough

The Elkhorn Slough Early Mitigation Partnership (ESEMP) brought regional stakeholders together to identify sensitive resource sites and develop funding strategies to enable early, regional-scale mitigation. The ESEMP serves as a model of balancing transportation improvements with ecological protection and enhancement.

The Elkhorn Slough in California's Monterey Bay is a sensitive ecosystem. It is the largest tract of tidal salt marsh in the State outside of San Francisco Bay and provides important habitat for plants and animals. Because the region is also in need of many major capacity and operational improvements over the next 20 years, 11 local, regional, State, and Federal agencies as well as the Elkhorn Slough Foundation signed a Memorandum of Understanding (MOU) to apply regional ecosystem conservation strategies in early mitigation planning and transportation decision making. The Information Center for the Environment (ICE) at the University of California Davis provided valuable technical and facilitative support.

Geographic Information System (GIS) tools pooled data from various resource databases to identify special status species, habitat types, plant communities, habitat connectivity needs, and development pressures in the watershed. The GIS tools then identified priority sites for mitigation activities based on ecological connectivity, restoration, enhancement, and protection of many natural resources, including:

  • Wetlands that include freshwater and saltwater marshes and riparian corridors;
  • Oak woodland, maritime chaparral, and coastal prairie grassland; and
  • Federally listed species such as the Santa Cruz long-toed salamander, the California red-legged frog, the California tiger salamander, the southern sea otter, the Monterey spineflower, and the Yadon's rein orchid.

The ESEMP avoids project-by-project approaches to mitigation, includes a longer timeframe for monitoring success, and maximizes ecological benefits from mitigation activities. Since the ESEMP identifies key sites now for future mitigation, it enables transportation agencies to buy property in today's dollars, thereby avoiding cost escalation factors that can later make such purchases impossible and securing prime spots for conservation and protection before further development pressures take them away.

For more information, contact Gary Ruggerone at Gary_Ruggerone@dot.ca.gov, Nancy Siepel at Nancy_Siepel@dot.ca.gov, or Larry Vinzant at Larry.Vinzant@dot.gov.

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