In an effort to reduce nitrogen pollution in Wareham's waterways, the Board of Health is proposing a regulation that would require "denitrification" septic systems for any new construction that is 500 feet from wetlands or water bodies.

The proposal would update an existing Board of Health regulation, which requires the same for new construction within 150 feet of bodies of water.

A second part of the proposal would require that residents with failed septic systems who live 500 feet from a waterway also install a denitrification system. The proposal affects properties with on-site wastewater treatment systems — not users of the town's sewer system.

Denitrification septic systems are designed to remove nitrogen from wastewater, and the Board of Health proposal would require that the systems meet 19 milligrams or less of nitrogen per liter of wastewater discharge on an annual average.

To compare, a standard "Title 5" septic system gets approximately 28 to 35 milligrams of nitrogen per liter of wastewater discharge on an annual average.

Denitrification septic systems can cost approximately $10,000 to $15,000 more than standard Title 5 systems.

"Our water bodies and rivers are impaired, and we're trying to reduce the amount of nitrogen that makes its way to the water bodies," Health Agent Robert Ethier explained. "Our intent, as the Board of Health, is to protect the water quality and protect the water bodies in the Town of Wareham."

Earlier this year, a bylaw proposed by the town's Clean Water Committee that would have required denitrification systems for the construction of all new homes or commercial buildings anywhere in town, or to buildings expanded in such a way that would increase the output of wastewater, failed at Town Meeting, after public outcry about the cost of such systems. Voters also thought that the Board of Health should be the body to come up with such a regulation, as that is the body that would enforce it.

That proposed bylaw was supported by the nonprofit Buzzards Bay Coalition, which works to protect and restore the bay.

Rachel Jakuba, Buzzards Bay Coalition vice-president for advocacy, said the Coalition is also very much in favor of the current proposal.

"There are a few towns in Southeastern Massachusetts where the Board of Health has this type of regulation," Jakuba noted. "It's limiting the amount of future nitrogen pollution. That's valuable. … It's a very important first step to stopping the problem."

The problem with nitrogen, which is naturally present in human waste and found in fertilizers, is that it makes things grow. When nitrogen pollutes waterways, invasive species such as algae grow out of control and use up the oxygen, which in turn causes fish, shellfish, and other marine life to die.

Zach Pilotte, a Gateway Shores resident, spoke against the proposed regulation during a recent Board of Health public hearing. Pilotte, an engineer, is concerned that there is not enough evidence that denitrification systems are effective.

"It seems that the Wareham Board of Health is trying to move forward on a plan that really isn't based on any kind of scientific evidence," Pilotte argues. "I hate to see a regulation put in place just for the sake of regulating."

How to reduce nitrogen pollution has been a hot topic in town in recent years.

In October, 2010, a bylaw that required that developers contribute no new nitrogen to the watershed was passed by Town Meeting, but later repealed after officials found that the bylaw was essentially unenforceable, and had not been enforced anywhere else.

The Board of Health next discuss the proposal at a January meeting. Wareham Week will publish that date once it is finalized.