The large Itaipu dam, between Paraguay and Brazil, is facing an energy production crisis because of record low river and rainfall levels.
Experts say those low levels could last into 2022.
The Itaipu dam supplies about 10 percent of the energy used in Brazil and 86 percent of energy used in Paraguay.
The dam has recorded its lowest energy production levels since it began full operation in 2005.
Hugo Zarate is head of operations at the Itaipu dam.
He told Reuters "we have available power, what we don't have is water to sustain that power for a long time."
He added that the dam was "meeting the demand, but for short periods of time."
Zarate estimated that energy production at Itaipu would be between 65,000 and 67,000 gigawatt hours this year.
"That's about 35 percent of the maximum value of 2016 and 15 percent less than in 2020," he said.
The low levels affected both power production and the money the countries receive for the use of the water.
The drought, or severe lack of water, is one of the worst in the last 100 years.
Brazil's government has asked its citizens to reduce their use of electricity and water.
The drought has also affected production at the Yacyreta dam, between Paraguay and Argentina.
Yacyreta produced half the normal level of energy in September.
Both dams depend on the flow of the Paraná River and have limited ability to store water.
River flow is controlled by about 50 dams in Brazil.
Those dams have seen water stores decrease since 2019 because of lower rainfall levels.
Workers at Itaipu say the dam normally averages an inflow of about 11,000 cubic meters per second.
Yacyreta workers say that dam normally averages about 14,500 cubic meters per second.
So far this year, the average flow in Itaipu is 6,800 cubic meters per second.
Zarate says that is similar to levels in the 1970s.
Average monthly inflows for Yacyreta are between 6,000-9,500 cubic meters per second, said Lucas Chamorro.
He is the dam's head of water studies.
Weather expert Isaac Hankes says below normal rainfall seems likely for southern Brazil for the rest of the year.
"Plenty more rain is needed to ease drought concerns," he said.
Zarate said the Itaipu dam "totally relies on the improvement of the water flows."
He added that if water flow does not improve, the energy crisis will continue into 2022.
I'm Jonathan Evans.
1. meet the demand 满足需求
We can't meet the demand for the product.
2. average 平均为
Economic growth is expected to average 2% next year.