The U.S. Coast Guard has scrapped a controversial plan to periodically close parts of the Great Lakes for machine gun firing drills, the guard said Monday.

Environmentalists and mayors in the U.S. and Canada had attacked the plan to occasionally close 2,500 square miles of 34 near-coastal "safety zones," including zones near Gary and Michigan City, for live ammunition practice with boat-mounted guns.

The guard will explore "alternatives" to firing in the zones, said Rear Adm. John E. Crowley, commander of the 9th Coast Guard District. The guard, which suspended live-fire training on the Great Lakes in September after the controversy erupted, will not restart drills without a new plan, new rules and public notification, Crowley said.

"We will not conduct any firing prior to any issuance of a new regulation," he said.

Local environmentalists lauded the plan's cancellation.

"We're all just thrilled to death that they've made this wise decision to drop it," said Cynthia Fredrick, of Gary's Miller neighborhood. Fredrick volunteers for the Save the Dunes Council and is involved with the Alliance for the Great Lakes. She objected to the guard shooting lead rounds into Lake Michigan.

"We get our water there. This is something we really have to protect," she said.

Tom Anderson, executive director of the Save the Dunes Council, had voiced concern that the drills were held at all, even though the guard suspended the drills in September, after holding them from January through August. He was pleased Monday with the cancellation of the plan.

"It may be belated ... but I think that in the long run, the public interest has been served," he said.

Michigan City passed a resolution asking the guard to rework the safety zone plan. Councilwoman Pat Boy said she and other council members understand the need for realistic training.

"It wasn't that we didn't want them to do anything, just to rethink how they were going to do it," she said.

U.S. Sen. Dick Durbin, D-Ill., commended the decision, saying in a statement: "Today's decision shows that the Coast Guard is committed to (conducting exercises) in a way that keeps Chicago area residents and businesses safe and informed."

U.S. Rep. Pete Visclosky, D-Ind., could not be reached for comment Monday night.

Gary environmentalist Lee Botts said the Coast Guard clearly heard public concern.

"Obviously, they had to respond to public opinion," she said.

The Associated Press contributed to this report.