The emergency services were alerted to the accident at the dam at Stigsjö outside Härnösand on Sunday morning, and managed to force open a second door by about 2pm, lessening the flow.
“One of the doors has broken open,” Erik Englund, from emergency services in Sweden’s High Coast region, told Sweden’s SVT broadcaster.
“If we hadn’t succeeded, there was a risk that the water would have taken away the whole old mill there is up here. But we managed to get it open.”
SMHI last week issued a Class 2 warning in Sweden as a result of an unusually strong 'vårfloden', the snow melt which swells watercourses across Sweden every spring.
The warnings apply to the Gävle River as well as to smaller watercourses in central Sweden close to the Norwegian border.
“There are still high water flows in many parts of northern Sweden and in eastern Norrland,” the agency said in an update on Monday morning. “Flows are increasing in the northern part as a result of increased snow melting.”
Englund said he expected the difficult situation to continue around Härnösand into this week.
“The flow is extremely powerful, and it is probably the spring flood that is behind it all. As it’s getting hotter now, we can’t expect the flood to end in just a few days.”