A program that would require boaters to pass a 30-minute training course to legally pull watercraft on a trailer in Minnesota ran aground Wednesday when its launch was postponed by the Department of Natural Resources.

Intended to fight the spread of aquatic invasive species, the controversial program was to begin at the end of the month. But legislators have introduced bills to kill the law requiring the training, and DNR officials don’t want boaters to take the course if that happens, or major changes are made.

Boaters who pass the test would get a decal for their trailer, and people transporting boats on a trailer without a decal could be ticketed.

“We didn’t want people to take test and get the decal now if there will be changes to the law,’’ said Bob Meier, DNR assistant commissioner.

Under the law passed in 2012, anyone using a trailer to haul a boat or water-related equipment such as a dock or lift in Minnesota is required to take aquatic invasive species training and display a decal on their trailer, starting July 1. About 542,000 motorboats are registered in the state.

Meier said the DNR doesn’t support repealing the law, but agrees some changes might be necessary. He said the education required under it still is needed, because other laws intended to prevent the spread of aquatic invasive species, such as zebra mussels, continue to be violated by far too many boaters.

“There’s a roughly 25 percent violation rate,” Meier said. “That’s just unacceptable.”

But Meier said the DNR recognizes there are concerns with the way the law is written. For example, people transporting boats on trailers through Minnesota to another destination are required to take the education course and display a decal even if they don’t put their boat in Minnesota waters.

“If I live in Iowa and I’m going to trailer my boat through Minnesota to Canada to go fishing, I’d have to take the test,” Meier said. “That’s probably not needed.”

Added Meier: “And technically, a trailer of brand-new boats from the New York Mills Lund factory would need a sticker on that truck. We need to figure out who it will apply to, when it will apply and what are the circumstances for not complying with it.”

At least three bills have been introduced to repeal the law, and the authors include both Republicans and DFLers.

“The concern is the program doesn’t work,” said Rep. Dave Dill, DFL-Crane Lake, co-author of one of the bills to repeal the law.

“You’re going to charge someone from Wisconsin [for a boat decal] to drive across Minnesota to go duck hunting in North Dakota? It doesn’t work. We have to find something that does work.”

Sen. Dave Tomassoni, DFL-Chisholm, who has authored a Senate bill to repeal the law, agreed that training is a good thing, and said out-of-state boaters need to know their obligation to not spread invasive species in Minnesota waters. But he said more work needs to be done to clarify the law. His bill, he said, is a starting point.

“This is complicated stuff,” Tomassoni said.

Resort owners have lobbied against the law, saying it could hurt summer tourism.

But Jeff Forester, executive director of Minnesota Lakes and Rivers Advocates — which represents about 6,000 lake associations — said aquatic invasive species remain a major threat to the state’s lakes and rivers, and his group supports more education for boaters. He’s tested the DNR’s online course.

“It’s very well done,” he said.

Forester said his group is “ready and willing” to work to make the law better.

Meanwhile, even if the Legislature doesn’t repeal the law and it goes into effect July 1, Meier said there should be time to launch the training program.