California’s largest internal body of water is steadily drying up, exposing a lake bed that threatens to trigger toxic dust storms and exacerbate already high levels of asthma and other respiratory diseases in Southern California. Yet there is something about the Salton Sea that leads many lawmakers to ignore the urgency and put off remediation programs. It’s just so far south — off the mental map of officials who represent more densely populated urban areas to the north, like Los Angeles. It is hydrologically unconnected to the Bay Area and the Sacramento-San Joaquin River Delta, which supplies water for so much of the state’s agricultural and residential use. It is a disaster in the making, yet it is an afterthought.