Haze hung over the Salton Sea on a recent winter day, while black-necked stilts and kildeer waded in the shallows, pecking at crustaceans. Something else emerged a few steps closer to the lakeshore: a briny, rotten egg stench wafting from the water. The Salton Sea is nearly twice as salty as the ocean, laden with agricultural runoff and susceptible to algal blooms that spew hydrogen sulfide, a noxious gas. It’s also a haven to more than 400 bird species and a key stop on the Pacific Flyway, one of North America’s main bird migration routes.