Water rising beneath the ground, pushed up by intruding salt water as sea levels rise, now impacts thousands of toxic waste sites throughout the San Francisco Bay Area. A six-month investigation by NBC Bay Area found that the threat from rising groundwater isn’t decades in the future but, in some cases, may be imminent. In many hot spots from the North Bay to the South Bay, UC Berkeley scientists told the Investigative Unit they’ve recorded groundwater already at or near the surface.