A drought sign is seen in a field near Buttonwillow Thomson Reuters WASHINGTON (Reuters) - The West Coast could see power brownouts in coming months as hydro power stations struggle with the four-year drought, and in the longer term climate change could cause additional problems for power plants, the U.S. energy secretary said on Monday.

"That is certainly a risk," Energy Secretary Ernest Moniz told reporters at a Christian Science Monitor breakfast on Monday, when asked whether the region could see a summer of power brownouts, or reductions in availability of electricity supply.

"Hydro power is a renewable (form of energy) but if you look historically there is actually quite a bit of fluctuation from year to year, depending upon what happens over the winter," he said.

California's mountain snow pack, which usually provides about a third of the state's water, is at the lowest level on record, according to the California Department of Water Resources. Power stations that depend on that water flow in the heavy demand summer months are expected to generate far less electricity in coming months than average, it said.

California Governor Jerry Brown, this month ordered his most sweeping action to combat the drought, ordering residents and businesses to cut water use by 25 percent, although farmers are exempt.

Moniz said hydro power outages are perhaps the major long-term risk to the energy water nexus that could result from climate change, both in the United States and in the wider Western Hemisphere. But he added that there are other concerns.

Power stations can also shut down when water temperatures get too high and rising sea levels can make storms more damaging in coastal areas with dense energy infrastructure like Houston and the East Coast, Moniz said.

(Reporting by Timothy Gardner; editing by Gunna Dickson)