CARACAS -- Venezuela, a country with vast reserves of oil and natural gas, as well as massive rushing waterways that cut through its immense rain forests, strangely finds itself teetering on the verge of an energy crisis.

Venezuela's seemingly endless resources have allowed the government for decades to just about give away its gasoline -- a full tank of gas in Caracas costs about the same as a can of soda.

But due in part to the assumption by many Venezuelans that energy in all its forms would always be cheap and plentiful, the country is suddenly starved for electrical power, and officials are warning of a possible calamity.

President Hugo Chávez, who won the presidency 11 years ago, in 2007 fully nationalized what was then an already heavily regulated and mostly state-run electricity sector. Over the years, the sector suffered from a dearth of investment despite sharply rising demand that was fueled by government subsidies that make electricity cheap.

That has left Venezuela, which like most South American countries depends heavily on hydropower, vulnerable. Last year the country was beset by a drought. Water levels at the Guri Dam, which is one of the world's largest hydroelectric dams and supplies Venezuela with 73% of its electricity, have receded quickly. As a result, the government can't generate enough power to meet demand. Mr. Chávez's electricity minister, Angel Rodriguez, this week said the country is facing an "emergency situation."