DNR warns: Don't blast plants and lake bottoms with water jets

State environmental officials are warning lakeshore property owners to be careful if they use high-powered water jets to clear away plants or muck.

These devices, sold under the brand names like Aqua Thruster, Aquasweep or Torrent Muck Blower, are referred to by the Minnesota Department of Natural Resources as "hydraulic jets." The jets, which resemble outboard motors, can be a handy tool to clear the waters around a dock or swimming area.

But used incorrectly, they can wreak havoc.

"They can do a lot of damage to the bottom of the lake and vegetation and different things," said Capt. Aaron Kahre, administrative manager at DNR. "There's always a bit of a learning curve to use it properly."

In lakes with softer bottoms, the jets can be particularly destructive to plants and fish habitat, Kahre said.

A permit is almost always needed to use the jet cleaners, Kahre said. The DNR has found illegal use of the jets after being tipped off, or by spotting it from the agency's planes.

Jeff Forester, the executive director of Minnesota Lakes and Rivers Advocates, said the use of water jets can stir up another problem — algae blooms.

The blooms are "becoming more and more of an issue as water warms" from climate change, Forester said.

Forester said property owners using the jets should avoid pointing them downward. In addition to the DNR, Forester said lake associations are working to educate jet users on proper technique.

While Kahre said the jets have been an on-and-off problem since they became popular a few years ago, the number of citations issued has dropped.

According to data provided by DNR, 11 citations were issued in 2017. The number has dropped each year since then, with four given out in 2020 and one in 2021.

DNR officers have discretion on whether to issue a warning or a citation, Kahre said, and may choose to warn if they find someone using a jet without a permit who hasn't done significant damage to a lake.