San Francisco Bay Area DAMS a Warning San Francisco Bay Area DAMS a Warning   An aerial view of the dam and at homes below it at Anderson Lake Reservoir on Tuesday, Feb. 25, 2020 in Morgan Hill, Calif. Editorial: A warning for Bay Area dams 2/27/2020 An aerial view of the dam and at homes below it at Anderson Lake Reservoir on Tuesday, Feb. 25, 2020 in Morgan Hill, Calif. Life in California depends on the dams and reservoirs that provide water for homes, farms, recreation, energy and, not least, safety. That last function should be getting serious consideration toward providing overdue answers about emergency preparedness. The more than 1,200 earth and cement structures that stand astride rivers and canyons across the state look solid enough, but many were built before engineers fully understood the threat of nearby seismic faults. Compounding the danger, a large number of decades-old dams are operating without updated policies on emergency notification of communities and businesses that have developed downriver since they were built. This general worry has become specific in the case of one Bay Area dam. Federal regulators want the Anderson Reservoir in Santa Clara County drained dry beginning this fall out of concern that the Calaveras Fault could unleash a disastrous jolt to the dam above Morgan Hill. Valley Water, the dam’s operator, disagrees, arguing that the lake is low enough now and that more releases could harm part of the facility. At stake is a needed water supply for the booming Silicon Valley and the economic health of the region. This standoff needs to be resolved. There are years-away plans to rebuild the dam, but federal regulators are in no mood to wait. Their order affects the county’s largest reservoir, though there appears to be enough supply to ward off major repercussions for water users. Chronicle Editorial Board The dam’s condition highlights another concern: If there is an emergency, dams should have quick-response plans to alert homes and businesses downriver. Three years ago, the Oroville Dam, the nation’s tallest, experienced a near disaster when an aging spillway crumbled, threatening the structure and forcing the evacuation of some 180,000 people downstream. The same winter’s heavy rains caused a spillover of the Anderson Reservoir that flooded neighborhoods in San Jose with little advance warning. The Bay Area needs better preparation for such dangers. A Chronicle report Wednesday showed at least 47 of 145 dams in the region don’t have updated plans to notify authorities and downriver communities in an emergency. The state requires such plans and should make a concerted effort to ensure that they are in place. This region is riddled with active fault lines that could precipitate a disaster. As the vagaries of climate change unfold, dams will be tested as never before. Droughts will alternate with heavy storm seasons, making water storage and flood control vital. In Santa Clara County’s case, a dry reservoir could mean taking more water from the federal and state water systems already facing competing demands from farmers and environmentalists. Dam safety is a crucial part of California water policy. It shouldn’t be neglected, especially when it comes to alerting the public if trouble looms. This commentary is from The Chronicle’s editorial board. We invite you to express your views in a letter to the editor. Please submit your letter via our online form: