This is disturbing news. Chinese officials are now warning that earthquake-damaged dams in Sichuan province may be strained to the breaking point:

Two hydropower stations in Maoxian county, where 7,000 residents and tourists remain stranded near the epicenter, were "seriously damaged". Authorities warned that dams could burst. Landslides had blocked the flow of two rivers in northern Qingchuan county, forming a huge lake in a region where 1,000 have already died and 700 are buried, Xinhua said.

Luckily, the massive Three Gorges Dam appears to have been unaffected.