PARIS — Heavy rains in France lifted the Seine on Friday to its highest levels since 1982, threatening Paris’s cultural institutions and soaking the French countryside east of the capital.

The Seine has continued to swell since the river burst its banks on Wednesday, raising alarms throughout the city. As of 10 p.m. on Friday, its waters had reached 20 feet. The river was expected to crest on Saturday morning at up to 21.3 feet, and to remain at high levels throughout the weekend, the French Environment Ministry said in a statement.