CAPE COD may be known for ocean breezes, waterbirds, and maybe some raucous seaside vacationers rolling through. But along one stretch, that could include the sound of more than a million bullets fired each year.

A years-long dust-up between Cape residents, local government officials, environmental advocacy groups, and the Massachusetts Army National Guard spun into a new chapter this spring. The US Environmental Protection Agency released a draft determination concluding a proposed $11 million multi-purpose machine gun range at the Joint Base Cape Cod in Bourne could pose a “significant public health hazard” by contaminating the Cape’s sole source aquifer. 

At a public hearing in Sandwich on Wednesday night, residents cited the EPA report in urging  that plans for the machine gun range be scrapped. 

Military officials want to clear cut about 170.5 acres of forested land, expanding an existing range on the base that hasn’t been in use for about 25 years. The military says their switch from lead to copper bullets, along with regular well monitoring and soil sampling on-site, ensures that there is no risk of water source contamination.

Over the training site’s history preparing soldiers since World War I, “small arms activity has resulted in countless millions of projectiles dispersed across the impact areas of the training site,” John Bagaglio, garrison commander of Camp Edwards at the joint base, said at the Wednesday night hearing. “Even after a century of small arms activity, the United States Army Corps of Engineer studies have concluded that small levels ranges have not resulted in groundwater contamination above any action level.”

But the EPA, after 20 months of evaluating the proposal, concluded in its draft report that the construction, operation, maintenance, and use of the machine gun range have the potential to contaminate the aquifer that supplies more than 50 percent of the drinking water for the nearby region of Cape Cod.

“The EPA’s view is a preventative approach is reasonable and warranted because of decades of environmental impacts that have already damaged the Cape Cod aquifer,” said Jane Downing, drinking water branch chief for the region.

Public comments on the proposal will be accepted through June 26, after which the agency will begin finalizing recommendations. If the proposal is still considered a threat to the aquifer, said Downing, “then there’ll be no commitment of federal funds that will be allowed.”

The back-and-forth has turned into an awkward referendum on supporting the military and supporting the already vulnerable water source. Though most who testified at the evening meeting objected strongly to the project, a handful said uncertainty is not a good enough reason to stand in the way of military readiness. 

“If these troops need the machine gun range, so that they can be trained so they can be competent to serve our country and to serve the taxpayers, then I say give it to them,” said one man who only identified himself as Andrew O. and scoffed at potential climate implications. 

Many residents in Bourne and nearby Cape towns have balked at the proposal since the initial pitch. 

Sandra Faiman-Silva, a Falmouth resident and anthropology professor at Bridgewater State University, said “the current debate over siting of the machine gun rage is a case of those who ignore the past are doomed to repeat it.” For decades, the base caused contamination to the Cape’s drinking water, leading to more than a billion in investigation and cleanup costs, she noted. 

She referred to a recent Cape Cod Times article, in which Major Alex McDonough, safety officer and deputy base operations manager at Cape Edwards, said, “We don’t want to poison anyone. We don’t want to poison ourselves, and we certainly don’t want to poison anyone in the surrounding towns.”

Faiman-Silva and others who testified say it may be too late on that front. “I think you already have and maybe you should just stop and take the advice of the EPA experts,” she said.