Portugal is restricting the use of some reservoirs for hydroelectric power and irrigation amid an unusual winter drought.
On Tuesday, authorities temporarily limited water use at some hydropower dams to prioritise human consumption.
The Portuguese Institute of Meteorology (IPMA) said that the whole country was enduring some degree of drought because of relatively low rainfall since November.
The IPMA added the situation had now worsened, with at least 45% of the country in “severe” or “extreme” drought.
Five hydroelectric dams in central Portugal will be almost totally shut down and another in the southern Algarve region will halt irrigation, the environment ministry announced on Tuesday.
The measure is required to ensure the drinking water supply for at least two years, minister João Pedro Matos Fernandes told reporters.
"The situation of drought is worrying," he said. "If the forecast becomes gloomier, we will have to go beyond these measures."
Portugal has about 60 hydropower reservoirs of varying sizes, which together produce 30% of the country's annual electricity consumption.
But Portugal has other reservoirs that are full enough to make up the shortfall resulting from the restrictions, Matos Fernandes has said.
With February forecast to produce little rain, the restrictions will remain in place until March 1 when they will be reassessed.
Portuguese farmers have already voiced concerns, saying the drought could "severely" affect their crops and cattle.