Environmental groups and irrigation districts are working to bring more salmon back in the Tuolumne River near Modesto. Salmon used to thrive in California, but decades of environmental degradation have reduced their population to about one percent of historical levels. Now people are trying to help them recover by rebuilding their habitat, but environmentalists argue that what’s really needed is just more water. Reporter: Katherine Monahan, KQED Learn more about your ad choices. Visit megaphone.fm/adchoices