Ahead of the start of the second day of this year's OneCape Summit on Tuesday, the Cape and Islands Municipal Leaders Association conducted some important business of its own.

The association voted to send a letter to the state Department of Environmental Protection voicing its support of the agency's draft decision to deny a modified discharge permit to Holtec, the owner of the decommissioned Pilgrim Nuclear Power Plant in Plymouth.

Holtec, which purchased Pilgrim in 2019, has been working toward securing a permit to discharge approximately one million gallons of industrial wastewater from the plant into Cape Cod Bay, which Brewster and Orleans both border.

The proposal has been met with pushback and protests from state and local officials, as well as citizen groups concerned with the environmental impacts the discharge would have on the bay and the region.

While Holtec has maintained that the wastewater can be discharged safely into the bay, Mass DEP in its draft decision last week said that the bay is protected from discharge from the plant under the state's Ocean Sanctuaries Act.

"The one comment we did hear was to sincerely thank DEP for taking this on and being so thorough," Kevin Galligan of the municipal leaders association, and a member of the Orleans Select Board, said Tuesday following the association's meeting. "So we'll make that loud and clear, thanking them for their hard work on this important issue."

The environmental watchdog group Cape Downwinders has been actively protesting the proposed discharging for more than a year.

"We're very pleased that the Department of Environmental Protection has ruled that the dumping of radioactive water into Cape Cod Bay is clearly illegal," said the group's director, Diane Turco of Harwich. "We have been pushing that since last year, that the Ocean Sanctuaries Act protects the bay from Holtec's plan."

State Sen. Julian Cyr, D-Truro, also applauded the draft decision in a statement last week, calling it "an incredibly meaningful win" for opponents to the proposed discharge.

"Cape Codders, Islanders, and people across southeastern Massachusetts are dedicated to protecting our waters — that's why we have continuously pushed back against the release of radioactive industrial water into Cape Cod Bay," Cyr said in the statement. "The Healey-Driscoll Administration's determination that Cape Cod Bay is a protected waterway under the 1971 Ocean Sanctuaries Act upholds a critical law that preserves our unique natural environment."

The Association to Preserve Cape Cod earlier this year provided legal analysis to the Healey-Driscoll Administration giving support for denying the permit under the Ocean Sanctuaries Act, according to the association's executive director, Andrew Gottlieb.

"That gave not only the ability, but the actual obligation to deny," he said. "So we were pretty gratified that this decision reflected the underlying analysis we provided to the administration."

While good news for opponents, the decision is only a draft, and Mass DEP still must issue a final decision on the matter. A 30-day public comment period follows the release of the draft decision.

"This is a necessary process step that DEP has to take," Gottlieb said. "But we're quite confident that the public comment process will result in an affirmation of the tentative decision to deny."

An email to DEP spokesperson Edmund Colletta seeking comment on the agency's timetable for issuing a final decision was not returned as of The Chronicle's Tuesday deadline.

Holtec in a statement said it is "disappointed" by the DEP's draft decision, noting that opposition to the company's pursuit of the permit has delayed discharge efforts for four years. That delay has in turn set back the potential for the Pilgrim property to be repurposed to become "an economic driver for the Plymouth community."

"We will continue with the EPA modification process and will look to evaluate all options related to ultimate disposition of the water generated during plant operations for the last 50 years," the company said in the statement.

Gottlieb said he sees a few avenues Holtec might take if Mass DEP finalizes its decision to deny the permit. He said the company could appeal the decision, or it could also try and argue in court that the Nuclear Regulatory Commission has the final say on the disposal of nuclear waste, not the state.

While the company is likely to litigate, Gottlieb said doing so would be "frivolous" on Holtec's part. He said the Ocean Sanctuaries Act makes it clear that industrial wastewater from Pilgrim is not allowed into the bay.

"It's checkmate. Game's over," he said.

But Turco said as far as the Downwinders are concerned, Holtec must still be challenged until the company abandons any and all plans for dumping the wastewater.

"This fight is not over until the deal is sealed, until Holtec says 'We are not dumping into the bay. We will consider other options only,'" she said.

Email Ryan Bray at ryan@capecodchronicle.com