Climate change impacts drive the need for efficient use of both water and energy, according to experts. Water and energy supplies are closely linked. The water sector is the largest user of electricity in the state. Conversely, water also generates up to 20 percent of the state\u2019s power supply through hydroelectricity. The fallout from climate change is highlighting legal and institutional system flaws in these areas, experts say. That includes the failure to require that diversions to agriculture and home taps from our rivers and streams be measured. Also missing is whether this essential and diminishing resource is being used efficiently. \u201cDiversions will increase with lower surface water flows,\u201d warned Michael Hanneman, University of California at Berkeley professor of environment and resource economics. Greater demand on diminishing water supplies is expected to increase use of groundwater pumping. \u201cIt looks like a train wreck,\u201d Hanneman warned.