There are 60 coastal septic systems in the Boothbay region that use above-ground overboard discharge systems; and a state-wide effort to remove them is aimed at reducing pollution of marine life.

Since the 1970s, overboard discharge systems (OBDs) have offered an alternative for homeowners unable to connect to a municipal facility and whose land did not have enough soil to dig an in-ground septic system. Their wastewater is run through the system and emptied into nearby bodies of water.

The state Legislature, along with the Department of Marine Resources and Department of Environmental Protection (DEP) are concerned about people are not monitoring their septic systems closely enough and also about system failures. The DEP has been trying to replace these systems with newer technologies.

In order to sustain various species of marine organisms, such as clams and oysters, water bodies need to have certain amounts of dissolved oxygen. Nonpoint source pollution, such as water runoff from municipal streets, septic systems and excess waste from projects like an aquaculture farm reduce the amount of dissolved oxygen in the water. 

Biologists have been measuring tidal flows and dissolved oxygen levels in Linekin Bay. The bay lies within a region the called Area 22, covering Southport, Boothbay and Boothbay Harbor, an area that is closed to shellfish harvesting.

Studies show there is a decreased level of dissolved oxygen there, which is why the state agency wants to eliminate the septic systems, to whatever extent possible. While septic systems play a role in reducing dissolved oxygen levels, there are other factors that affect the overall health of the bay.

How do OBDs affect water quality?

Passers-by along some areas of Route 1 may notice a pungent rotten-egg odor emanating from the mud flats in the height of summer. David Courtemanche, a biologist and division director of Environmental Assessment at the DEP said this smell is a sign of a lack of oxygen or “hypoxia” where dissolved oxygen levels are too low to sustain shellfish. 

Bacteria is the heart of any waste treatment system, from a town sewer district to a compost toilet. These systems needs food (carbon-rich waste), warmth, shelter and oxygen to operate. All discharges, Courtemanch said, create a “biochemical oxygen demand,” the activity by which bacteria consume carbon in waste and use up dissolved oxygen in the water. 

In the past several years, clam diggers in towns from Yarmouth to Waldoboro have worked to eliminate shoreline pollution to keep the mud flats open for shellfish harvesting. Their conservation efforts have included maintaining seed stocks and requesting help from landowners to update septic systems.

Angela Brewer, a marine biologist at the DEP water quality office, said it is difficult to determine the extent of overboard discharges on dissolved oxygen levels in Linekin Bay. Other pollution sources, such as water runoff from streets, and the motion of tides also affect the measurements of dissolved oxygen. She said the dissolved oxygen level in Linekin Bay, like other bays along the Maine coast, may also be a natural occurring phenomenon.

Chris Higgins, supervisor of the Boothbay Harbor Sewer District, believes not all overboard discharge systems are regulated enough. 

He said employees test twice per week to make sure the facility is meeting the biochemical oxygen demand requirement. Every overboard discharge system is designed to handle a certain amount of flow, the amount of wastewater that is treated and flushed. The sewer district is designed to handle 640,000 gallons per day, but in peak summer months they average around 450,000 gallons a day. 

Higgins is also a sewer systems contractor. He said a typical system uses about 90 gallons per person per day. He said residential overboard discharge systems are not tested analytically, but physical checks of the systems are taken once per year.

“What are the chances these systems are being disinfected?” he said.

He said the systems function the same way the Boothbay Harbor Sewer District operates, however there are no guarantees homeowners are caring for their overboard discharge systems. 

“That’s why I think the state wants to eliminate OBDs,” he said “It’s tough to regulate them. Do you make a homeowner take lab tests of their effluent on a monthly basis, on a weekly basis? I think they should. We have to.”

Working to cut back OBDs

Sebastian Belle heads up the Maine Aquaculture Association. He said Maine has the strictest monitoring system in place for aquaculture farming in the United States and 16 other developed countries.

“That's not a bad thing, necessarily,” he said. Belle added that he and others have appealed to the legislature for stricter environmental regulations, to cut back on pollution and to cut back on overboard discharges.

In 2010, the 124th Legislature passed amendments to overboard discharge laws to expedite the phase out of these septic systems.

Belle said aquaculture farmers lobbied hard before the Maine Legislature to enforce a rule that requires additional inspections for overboard discharges whenever property is transferred. According to state statute, overboard discharges must be inspected when property is transferred even to a relative of the owner.

As of December 2011, there were 1,250 overboard discharge systems in the state, mostly along the coast, according to Brian Kavenah, director of Water Quality Management at the DEP. He said 60 of these systems were licensed in Boothbay Harbor. 

A map that shows the location and status of all overboard discharge systems is available for at www.maine.gov/dep. There are approximately 17 overboard discharge systems whose licenses have expired. Some expiration dates extend into the mid-1990s, while others are due to expire in the coming year. Kavenah said his department is seeing the removal of approximately 50 overboard discharge systems a year on average. 

The newer systems use a septic tank, customized leach field and, in some cases, pump systems. According to Kavenah, the average replacement cost is about $25,000, but certain systems can be more expensive.

The overboard discharge removal grant program funded by state bond money helps facilitate this process by assisting homeowners in the switch from an overboard discharge system to another method. 

Grant funding is available for primary residences with overboard discharge systems whose homeowners' annual income is less than $125,000 a year.

“The idea is that the homeowner should be able to finance the removal of an overboard discharge system,” Kavenah said.

Homeowners may also be eligible for a low interest loan to help fund an overboard discharge removal through the Maine State Housing Authority.

Approximately 10 percent of all overboard discharge systems in the state are expired, according to Kavenah. Some of these systems, however, are in the process of removal. A compliance inspector works with conservation aides throughout the summer months keeping tabs on these septic systems.

Despite their efforts, not all overboard discharge systems can be replaced. 

“With Linekin Bay, I would say some OBDs will stay there,” Kavenah said.

Since many homes are sitting on ledge, there is not enough soil to build an alternative method for getting rid of the waste.