COPENHAGEN, Denmark—A dam in southern Norway partially burst Wednesday following days of heavy rain that triggered landslides and flooding in the mountainous region and forced downstream communities to evacuate, officials said.
Authorities initially considered blowing up part of the dam at the Braskereidfoss hydroelectric power plant to prevent communities from being inundated. But the idea was scrapped after water later broke through the structure, police spokesman Fredrik Thomson told reporters.
“We hope that we will get a gradual leveling of the water and that we will get an even leveling.”
The power plant on the Glåma, Norway’s longest and most voluminous river, was under water and out of operation.
Huge volumes of water were pouring over the western parts of the concrete dam, Mr. Thomson said.
For hours, the water gathered behind the dam. Then a parking lot next to the power station was flooded, and soon water started pouring through a gap in the concrete. The water ripped apart a two-lane road and fences that ran across the top of the dam.
“The water has gradually begun to seep through the side of the dam, and, as of now, it is not appropriate to take any measures at the power plant,” Mr. Thomson told reporters. He said the situation is being assessed continuously.
“The damage from a possible explosion of the concrete plant would be so great that it would serve no purpose,” Mr. Thomson said.
Per Storm-Mathisen, a spokesman for the power station operator Hafslund Eco, told the Norwegian news agency NTB that the water diversion seemed to be “going well.”
At least 1,000 people live in communities close to the river in the area, and authorities said that all had been evacuated before the dam began to fail.
Hatches in the hydroelectric power plant were supposed to open automatically if too much water collected behind the dam, but they failed to work as designed, according to Alexandra Bech Gjørv, board chair at Hafslund Eco. The reasons for the failure were unknown, she said.
In other developments Wednesday, a Norwegian woman in her 70s died after falling into a stream the day before. She managed to crawl up onto the bank, but police said because of the floods, it took rescue teams several hours to bring her to a hospital.
More than 600 people were evacuated in a region north of Oslo, and police in southern Norway reported that the situation there was “unclear and chaotic.” The Norwegian Public Roads Administration said Wednesday that all main roads between Oslo and Trondheim, Norway’s third-largest city, were closed.
”We are in a crisis situation of national dimensions,” Innlandet country Mayor Aud Hove said. “People are isolated in several local communities, and the emergency services risk not being able to reach people who need help.”
The weather system known as Storm Hans has battered parts of Scandinavia and the Baltics for several days, causing rivers to overflow, damaging roads and knocking down branches that injured people.
In neighboring Sweden’s second-largest city, Goteborg, large parts of the harbor were under water.
Weather agencies for both countries issued extreme warnings.
“This is a very serious situation that can lead to extensive consequences and damage,” the Norwegian Meteorological Institute said. Its Swedish counterpart issued a red warning for the west coast, predicting “very large amounts of rain causing extremely high flows in streams.”
Erik Hojgard-Olsen, a meteorologist with the Swedish Meteorological and Hydrological Institute, told the Aftonbladet newspaper that the weather was unusual for this time of year.
“It is exceptional to have such a low pressure [system] as Hans, which has brought so much rain for several days in a row,” he said. “Especially for being a summer month, it has lasted a long time.”
The Norwegian Water Resources and Energy Directorate upgraded its warning for floods and landslides from orange to red for parts of southern Norway. The agency said record high flood levels were recorded in several places in the Drammensvassdraget, a drainage basin west of Oslo, the capital.
Erik Holmqvist, a senior engineer at the agency, said four lakes. including the Randsfjorden, the fourth-largest in Norway, were particularly vulnerable to flooding.
“We have to go all the way back to 1910 to get the same forecasts for the Randsfjorden,” Mr. Holmqvist told the VG newspaper.
Norwegian Prime Minister Jonas Gahr Støre visited the affected areas of southern Norway. “When the rain stops, another challenge begins: The water needs to get out,” he said.
