City officials in Kent, Ohio, are warning people to stay off the Cuyahoga River, but recreational boaters continue to venture onto the waterway.

According to cleveland19.com, Kent Fire says it rescues an average of six people in boating situations during the summer. This year, 20 people have already been pulled to safety.

Large pieces of floating debris have also reportedly damaged vessels.

The high water is the result of damage to the dam at Lake Rockwell in Akron, Ohio, and repairs are reportedly expected to take at least a week.

In Cedar Rapids, Iowa, debris caused an incident that required the rescue of four people after their boat got stuck on a tree, according to krcg.com. Winneshiek County Emergency Management Agency, pulled grandparents and two grandkids from the boat.

Because of high debris content, the Iowa Department of Natural Resources is reportedly urging boaters to exercise extra caution.

“There may be branches or trees or other debris in the river that have never been there before,” conservation officer Ron Lane said in a statement.

North of the border in Canada, the Marine Chamber of Commerce said that the high water levels could cost U.S. and Canadian economies more than $1 billion in delays and possible stoppages in commercial shipping.

Attempts to control flooding on the St. Lawrence River and Lake Ontario have raised the outflow from the Moses Saunders power dam near Massena, Canada, to what local officials called “unprecedented levels” in a statement.