Sonny Bono Salton Sea National Wildlife Refuge

The Sonny Bono Salton Sea National Wildlife Refuge is located in California’s Imperial Valley, 40 miles north of the Mexican border, along the southern end of the Salton Sea. The refuge has two separate managed units, 18 miles apart, each one bordered by the Salton Sea on the north and by farmlands on the east, south, and west. Each unit contains wetland habitats, farm fields, and desert uplands. All the land that makes up the refuge is flat except for Rock Hill, a small, active volcano.

Because of its southern latitude, its location in the Sonoran Desert, and its elevation of 227 feet below sea level, the refuge sees some of the hottest temperatures in the nation. Daily temperatures from May to October exceed 100°F with temperatures of 116°-120°F recorded yearly. The Salton Sea Authority has measured the current salinity of the sea to be 60 PPT (parts per thousand); by comparison, ocean water is approximately 35 PPT. Despite the harsh environmental conditions, the Salton Sea supports one of the most diverse avian compositions in the United States as well as a host of endangered and other wildlife species.

Since its initial flooding in 1905, the Salton Sea has attracted a tremendous diversity of birdlife, drawn by the mix of saltwater and freshwater habitats, marshes, desert upland, and ryegrass fields. Migratory birds traveling along the Pacific Flyway have sought out this wetland oasis to refuel before continuing on their journey. Historically the sea has been a winter home for more than 90% of the western population of American White Pelicans and has hosted millions of eared grebes during their southward migration. On the refuge and in the immediate surrounding area, over 400 species of birds have been documented.

But over time, the Salton Sea has shrunk in size, in part because of the natural evaporation of water in the hot desert and reduced snow packs feeding the Colorado River and in part because of changing farming practices. As farm fields are fallowed to supply additional water to San Diego County, while others switch from flood irrigation practices to sprinkler irrigation. Combining all these factors with the fact that the sea has no outlet, it is no surprise to see that it has also grown saltier with each passing year. The sea is now almost twice as salty as the Pacific Ocean and has lost its ability to sustain the fish and organisms that are essential food for migrating birds except for where the agricultural water drains into the sea and the New and Alamo River Deltas. At a different time, other water bodies would have provided alternate spots for migrating birds. But with the loss and/or degradation of other suitable wetland habitats along the Pacific Flyway, all ongoing conservation work is essential to keep the Sea as a vital stopover site along the flyway.