With the creation of the Southwestern Riverside County Multi-Species Reserve in 1992, the Riverside County Regional Park and Open-Space District, and Metropolitan Water District of Southern California helped forge California’s first agreement for multi-species protection. Since the first land acquisitions of the Shipley Reserve and mitigation for Diamond Valley Lake construction subsequent acquisitions by MWD and its conservation partners have resulted in a nearly 14,000-acre reserve. The reserve now surrounds and connects both Diamond Valley Lake and Lake Skinner. Metropolitan committed nearly $14 million for initial management and habitat and species surveys and is committed to provide long-term management funding to ensure that mitigation agreements stay in force. A Reserve Management Committee composed of Metropolitan, the Riverside County Regional Park and Open Space District, the Riverside County Habitat Conservation Agency, the U.S. Fish and Wildlife Service and the California Department of Fish and Wildlife cooperatively manages the reserve.

The reserve is home to many sensitive bird, mammal, and plant species utilizing at least eight types of habitat. Three types of habitat dominate the reserve an interior version of coastal sage scrub known as Riversidean sage scrub, native and non-native grasslands and chaparral. Smaller habitats include coast live oak woodland, sycamore, and cottonwood willow riparian forests. Many notable species include the Stephen’s kangaroo rat, which lives in the reserve’s grasslands and open shrub habitats. The California gnatcatcher, which makes its home in low growing Riversidean sage scrub. The Bell’s sage sparrow which nest in Riversidean sage scrub and chaparral. The San Diego horned lizard and orange throated whiptail found in sage scrub, chaparral and grassland areas. The Payson’s jewelflower and Parry’s spineflower which grow in Riversidean sage scrub. And of course many other species occur on the reserve like mule deer, bobcats, coyote’s and mountain lions.