HELENA, Mont. (AP) — Federal officials said Friday they have approved new measures meant to prevent a repeat of last fall's mass bird deaths in a contaminated former open-pit mine in Montana, including noise-making cannons and radar and laser systems.

The measures also include the use of strobe lights and remote-controlled boats and aircraft to haze birds off the toxic water, plus strategically placed decoys to divert birds away from the Berkeley Pit in Butte, part of the nation's largest Superfund site.

Some of the technology can be deployed immediately, while others — including a laser net covering the pit — will need additional regulatory approval, said Nikia Greene, the project manager for the U.S. Environmental Protection Agency.

"We're going to try all that are available at this time," Greene said. "I know the cannons are available. Things like that, we're going to try right away."

Last November, between 3,000 and 4,000 migrating snow geese died when they sought refuge in the pit filled with 50 billion gallons of toxic, metal-laden water. The sheer number rendered ineffective the existing bird deterrent system, which includes noisemakers called Phoenix Wailers.

The spring migration season began on Wednesday, increasing the urgency to approve the new measures. If they are effective, the Berkeley Pit's waterfowl mitigation program will be permanently updated to include them for the fall migration and beyond, Greene said.

"Our priority is to make sure an incident like Nov. 28 never happens again," Greene said.

The new technology was detailed in a proposal drafted by Montana Resources and BP-owned Atlantic Richfield Co., the two companies that are responsible for the Berkeley Pit. Greene said the ideas in the proposal came from a variety of county, state, federal and community groups.

Montana Resources' environmental affairs manager, Mark Thompson, said he installed one of the four new propane-powered noise cannons at the edge of the pit on Friday. Other measures that will be put in place immediately include new sounds for the Phoenix Wailer noisemakers and the floating strobe lights for the water's surface, he said.

Testing on a remote-controlled boat will begin next week, and a high-speed airboat should be ready by the end of the month. Discussions with a vendor on the radar system are continuing, Thompson said.