All the Western states share a power transmission grid, but the area most likely to face problems similar to California's is the Northwest. Washington, Oregon, Idaho and western Montana depend heavily on hydroelectric power, an energy source facing a double challenge this year. The Bonneville Power Authority has been forced to draw down its reservoirs to spin generators in recent months under a federal order requiring energy suppliers to sell to California. The order has been lifted, but reservoir levels are perilously low. That wouldn't be such a concern in a year of normal rain and snowfall, but the snowpack in the Cascade Range this year is only 60 percent of normal.
Less runoff means less water refilling reservoirs to power turbines.
Normally, the agency helps out California during the summer, Mosey said. And because the other states in the West are linked through their common power grid, there is the potential that problems also could affect Colorado, New Mexico, Nevada, Utah and Arizona. If California's situation is severe enough, it could suck electricity from the rest of the grid and set up a ripple effect in other states' utility systems. California's peak demand for power is expected to exceed supplies from May through September, according to the Independent System Operator. The projected deficit will range from 3,030 megawatts in May to as high as 6,815 megawatts in June.