Mitigation Projects

Best Slough Vernal Pool Preserve

The Best Slough Vernal Pool Preserve is an 88.6-acre site located in southwestern Yuba County, California, east of the city of Wheatland and within the Southeastern Sacramento Valley Vernal Pool Region. The Preserve is part of a 217-acre overall property owned by Yuba-Sutter Disposal, Inc. (also known as Norcal Waste Systems), purchased to provide a buffer for the Ostrom Road Landfill located approximately 3,000 feet northeast of the Preserve.

The Preserve was designed to provide mitigation for the loss of vernal pool fairy shrimp and vernal pool tadpole shrimp habitat resulting from the Feather River, Bear River, and Western Pacific Interceptor Canal Levee Improvements Project as proposed by the Three River Levee Improvements Authority to satisfy the U.S. Fish and Wildlife Service Biological Opinion and U.S. Army Corps of Engineers permit. Vernal pool construction was completed in 2009 and resulted in the creation of approximately 9.41 acres of vernal pools/swales. The Preserve was underlain by soils known to support vernal pools in the region, is adjacent to vernal pool grasslands, and primarily supported irrigated pasture and low-functioning irrigated pasture wetlands; therefore, the Preserve represented an excellent opportunity to restore/create vernal pools and vernal swales in southwestern Yuba County.

Due to a long history of farming activities conducted on the site, few distinct historic vernal pool footprints existed; however, some vernal pool footprints could be identified using historic aerial photographs. Wildlands restored a vernal pool landscape designed with a natural density of vernal pools and swales using a combination of results from soil investigations, topographic surveys, and nearby vernal pool landscapes as a reference. A majority of the restoration occurred through the construction of vernal pools in existing upland areas. The remaining upland areas were allowed to revert to annual grassland to re-establish a natural vernal pool landscape.

The Preserve supports vernal pool plant and animal species, and upland areas are managed in a manner that benefit dependent wildlife species such as foraging raptors, including Swainson’s hawk. The dominant vegetation on the Preserve is irrigated pasture used for livestock grazing. The irrigated pasture is dominated by non-native grasses and forbs. Swainson’s hawk foraging and nesting habitat occurs on the overall property and the adjacent properties. CNDDB records indicate that there have been seven Swainson’s hawk occurrences recorded within 5 miles of the overall property. An active Swainson’s hawk nest was observed in the overall property, immediately north of the Preserve in April 2009 during a focused raptor survey. The upland vegetation on site supports suitable foraging habitat for Swainson’s hawk.

88.6 acres

Location: Yuba County, California

Mitigation Types

  • Vernal Pool Preservation
  • Swainson’s Hawk

Service Area

The Best Slough Vernal Pool Preserve is a project-specific mitigation solution for Yuba-Sutter Disposal, Inc. (also known as Norcal Waste Systems), purchased to provide a buffer for the Ostrom Road Landfill.

Approving Agencies

  • U.S. Army Corps of Engineers
  • U.S. Fish & Wildlife Service

For additional information on the Best Slough Vernal Pool Preserve, please contact Julie Maddox at (916) 435-3555 or