MACHIAS, Maine — Heavy rain throughout Wednesday night and Thursday caused the Machias Waste Water Treatment plant to overflow and spill into the Middle River. As a result, the Maine Department of Marine Resources has closed a significant portion of the area coastline to the digging of clams, oysters and mussels.

The overflow problem has existed since before Machias Town Manager Betsy Fitzgerald was hired four years ago. “It is a high flow event. It often happens,” she said Thursday. “I’m not making light of this.”

Fitzgerald said a $5 million overhaul of the treatment facility is imminent, with bids to be opened Dec. 18 and selectmen expected to ratify a contract on Dec. 23.

For nearly a decade, she explained, the Maine Department of Environmental Protection has had the wastewater treatment facility under an order to upgrade. But in 2004, she said, they cracked down while simultaneously helping Machias find the necessary funding.

A 2006 statewide bond issue provided $2 million, while a combination of other state grants and federal stimulus funds provided another million. The rest of the funding was raised through a U.S. Department of Agriculture Rural Development loan for $500,000 at 2.3 percent interest, combined with a $1.5 million USDA grant.

Fitzgerald said that once bids are opened and the contract is awarded, she expected work on the interior improvements to begin immediately. She said part of the project would include work on local sewer lines and the construction of a new sewer line across Dyke Bridge. None of the businesses on the eastern side of the cause-way is served by municipal sewer and Fitzgerald said it would be a great economic tool to have sewer lines on that side of the Middle River.

The DMR closure, which is effective immediately, prohibits digging, taking or possessing any clams, quahogs, oysters or mussels taken from the shores, flats, and waters of the affected areas.

For more information about the closure and which areas are affected, call the DMR Shellfish Closure Hotline at 800-232-4733.