How is San Diego’s water supply connected to other locations throughout our region? This blog, written by PhD Candidate Alida Cantor, looks at a particular connection: birds at the Salton Sea.

A quick background

The Colorado River supplies over half of San Diego’s water. The Colorado also supplies water for many other users– 25 million people and 3.5 million acres of farmland throughout the entire Colorado River basin. The river is known as one of the most controlled and over-allocated waterways in the world.

In 2003, an agreement (the Quantification Settlement Agreement, or QSA) was negotiated with the goal of limiting California’s over-reliance on Colorado River supplies. The agreement transfers water from farms in Imperial Valley to urban users in San Diego. This means a more secure water supply for urban water users in San Diego, but could have negative impacts for others throughout the broader region — including birds.

Birds at the Salton Sea

The Salton Sea, the largest lake in California, is a 400-square-mile salty lake in Imperial and Riverside Counties. Its water comes primarily from agricultural runoff—which means that taking water away from farms means less water flowing into the Salton Sea. This is very worrisome for many reasons, one of which is potential impacts on bird habitat. Less water means receding shorelines and increased salinity, which hurt bird habitat.

The Salton Sea hosts a lot of different types of birds– around 400 different species. This includes several endangered and sensitive species, such as the Yuma Clapper Rail. The Salton Sea supports about 40 percent of the entire endangered Yuma Clapper Rail population so this bird is considered very vulnerable to habitat decline at the Salton Sea.

Other birds at the Salton Sea include eared grebes, cormorants, yellow-footed gulls, and white and brown pelicans. Brown pelicans were once endangered, but their populations have rebounded since the banning of the DDT pesticide. White pelicans are not endangered but a large percentage of them- 30 percent- nest at the Salton Sea. More birds of concern at the Salton Sea include mountain plovers, burrowing owls, and black skimmers, to name a few.

As wetlands throughout the broader region have diminished due to development (about 90 percent of wetlands in California have been lost over the last hundred years), the importance of the Salton Sea as habitat for migrating birds on the Pacific Flyway has grown. Although the Salton Sea experienced large-scale bird die-offs during the 1990s due to avian botulism and other diseases spread by having so many birds in one place, it remains a very important habitat, and every year millions of migrating birds rely upon the Salton Sea as a stopover to rest and fuel up along their journey.

Thinking about what San Diego’s water system means for birds at the Salton Sea shows how we are connected via our water supply to other locations and species throughout the region. The story of our water doesn’t start or end when we turn on the tap.