Boon for water quality, ‘burden’ for homeowners

New nitrogen regulations and the town’s mitigation plan for Tashmoo could be another hit to the housing market.

A map showing the nitrogen management overlay districts for Lake Tashmoo and Lagoon Pond. The yellow parts inside a watershed while the light gray parts are outside of a watershed. —Courtesy Town of Tisbury

Tisbury is implementing a new requirement for septic-system technology intended to help reduce nitrogen pollution in Lake Tashmoo and Lagoon Pond, but some fear the cost for the upgrades could place another financial burden on homeowners.

The Tisbury board of health regulations — which the board voted through in September — are scheduled to go into effect in the beginning of 2024, and would impact some 1,500 properties near Tashmoo and the Lagoon. 

Under the revised regulations, the buyer or seller of a home would be required to install the best available nitrogen-removing technology at the time of a property transfer. 

The regulation is part of a larger, targeted wastewater management plan for Tashmoo that has been estimated to cost more than $40 million in total, and is designed to clean up the iconic Tisbury waterbody. The plan — which is waiting state approval — includes extending the town sewer line to what is labeled the B2 district, a business area along State Road, but the majority of the plan calls for adding nitrogen-removing technology to backyard septic systems.

The town is subsequently working on a plan to address pollution in the Lagoon, but it has yet to be fully realized.

The idea is to prevent excessive algae growth and the loss of aquatic life caused by nitrogen in the two Tisbury estuaries, not to mention compliance with the federal Clean Water Act. 

The nitrogen-removing technology for backyard septic systems, at the high end, can cost a homeowner as much as $50,000, not including annual monitoring and maintenance fees, which can be as much as $1,000 annually.

The systems, what have been called innovative/alternative systems, or I/A systems, reduce nitrogen coming from backyard septic tanks much more effectively than traditional, Title 5 systems. They’ve been heralded as a way to clean up coastal embayments, especially in more remote areas; they are also seen as alternatives to sewer systems, which can be expensive and massive infrastructure undertakings. 

But some local engineers and people providing inspections of Title 5 systems worry that the cost could have a profound impact on Tisbury residents. 

“It’s a worthy goal, but it comes at a cost,” said Doug Cooper, who provides inspection services for septic systems on the Island, and has decades of experience with septic systems. “This is going to be a huge burden for Tisbury residents.”

Cooper says these I/A systems are a viable solution to reducing nitrogen getting into the town’s waterways, which he said is a noble cause. But for some of the inspections that he has overseen locally, the technology can range as high as $50,000. The cost of the systems depends on a number of variables, like proximity wetlands, grade of yard, and whether an entire septic system needs to be replaced. But unlike sewers, which can be shared over the larger population, individuals can be stuck with a hefty bill to pay on their own. “Economies of scale,” Cooper said.

Officials who have helped plan the targeted approach to cleaning waterways maintain that cleaning up the town’s waterways is not only the right thing to do, but the state will likely be instituting new Title 5 regulations that could force Vineyard towns to address nitrogen pollution regardless. The state environmental department recently passed new regulations for Cape Cod, where water quality issues in local estuaries are likely much worse than the Vineyard.

“We need to figure out how to eliminate the nitrogen that is coming from our wastewater,” says Ben Robinson, a Tisbury planning board member who has helped plan for nitrogen reduction in Tashmoo and the Lagoon. 

Too much nitrogen in estuaries — which include the Lagoon and Lake Tashmoo — can lead to an excess of algae or algae blooms, which can subsequently choke out oxygen and lead to fish kills and an overall habitat loss.

Estimates in a 2015 report from the Massachusetts Estuaries Project (MEP) found that controllable nitrogen loads coming from Tisbury properties had to be reduced by 11,000 pounds to satisfy the nitrogen standards in the federal Clean Water Act. 

About 75 percent of that nitrogen was coming from backyard septic systems. The report also found that eelgrass, habitat for shellfish and other aquatic life, was dying off.

“This is a commercial, marketable solution that is proving that it works,” Robinson said of the innovative/alternative backyard systems planned for the Tashmoo watershed. Unfortunately, he says, this technology is expensive. 

Robinson says that the town’s plans — instead of adding sewers to all of Tisbury, which would likely be more expensive — is putting some of the onus on a property sale. Homes are selling for upwards of $1 million to $2 million dollars, so putting in the nitrogen-removing technology is only a fraction of that sale price. And many of those are going to second homes or investment properties, he said.

Robinson also says that there will be low-interest loans available to homeowners, as well as grants and subsidies. Additionally, the health board can provide waivers to low-income homeowners who can’t afford a $50,000 upgrade.

But Robinson said that the plan can be changed if there need to be adjustments. ”We’ll have to pay attention to unintended consequences, to make sure there’s not too much of a burden on taxpayers,” he said.

The health board first created the town’s nitrogen regulations in 2016. The initial regulations required the installation of the best available nitrogen-removing technology when a septic system failed within the two watersheds, or when a new house was built. 

In 2018, the town of Tisbury began a pilot testing program for enhanced I/A septic systems. The project was partially funded through a grant from the Massachusetts Clean Energy Technology Center, and installed a number of these systems around Tashmoo to test their effectiveness. 

There are currently two commercially available enhanced I/A systems that are achieving significant reduction in nitrogen from wastewater (under 10 milligrams per liter of water or less), called Nitrex and NitROE. Both utilize a wood chip–based treatment system. The woodchips provide a carbon source for naturally occurring bacteria to break down the nitrogen to harmless nitrogen gas (a process called denitrification). The systems are installed between a leech field and holding tank. Nitrex reports an overall average removal rate of 97 percent of nitrogen.

The Tisbury health regulations would require a 75 percent removal, or not more than 13 mg/liter of nitrogen.

Last year, the Tisbury health board expanded the nitrogen regulations to say that any new construction would require innovative/alternative technology.

The latest amendment going into effect in January requires the installation of the technology whenever a property is transferred. Either the seller or the buyer of the property would be responsible for the cost of the installation.

As of February, the health department reports that there are 854 septic systems in the Tashmoo watershed, and 680 in the Lagoon watershed, that are subject to the new nitrogen regulations. Health agent Maura Valley says that several homeowners have already installed the new nitrogen-removing technology. 

Local real estate agents say that the septic system regulations will likely be used during the negotiation of a home sale, and would add another expense on the sale of a property. David Lott with Vineyard Open House says that buyers are already looking at an expensive market, on top of the 2 percent tax on a sale going to the Martha’s Vineyard Land Bank; and there’s also potential that another 2 percent tax could be imposed for a housing transfer fee. 

“Septic systems are just one additional hurdle they are facing,” Lott said. “The combination of everything on the Vineyard is slowing the market down.”

Lott, like Cooper, understands that preventing nitrogen pollution is essential for Tisbury as the town’s waterways have been degraded. But he worries that it will have another impact on homeowners.

The targeted nitrogen plan for Tashmoo was recently completed and submitted to the state. Consultant Scott Horsley and David Formato of Onsite Engineering put the 37-page report together. The town awaits an OK from the Massachusetts Department of Environmental Protection before it can go to voters for funding at town meeting in the spring.


  1. This article calls this “new” technology.
    When i met Anna Edey in the early 1990’s
    she had this “new” technology down.
    Simple simple simple.
    when I built my house in 1999
    I wanted to put her technology in my system.
    The town/state would have none of it, and I
    was required to put in a title 5 septic system.
    If it’s not adequate, the state– that required it–
    should pay for the upgrades.
    I understand that there are simple minds working
    for the government.
    But Anna knew years ago there would be problems.
    I salute you, Anna, and flip a bird to the simple
    minds that could not comprehend a simple solution.

    • I worked at the black dog when they implemented one of Ms Eddy’s designs. To say it did not go well is an understatement. Her design might have worked for you. It might not have. She recognized the problem, sure. That doesn’t mean her solutions were correct. Might have cost you tens of thousands more if her design had been approved. Just no telling.

      • Harrison.
        The project at the Black Dog was a poor
        choice for a demonstration project.
        Either through the existing habits of the
        staff that didn’t properly handle
        the issues associated with the grease, or
        the inadequate placement, maintenance
        and quantity of the grease traps it was a
        rather spectacular failure. Agreed !
        But we learn from failure. Certainly, lesson # one
        there was this doesn’t work in all situations.
        We are certainly learning about the failure
        of title 5 right now.
        Widespread acceptance of composting
        toilets would certainly help, but that’s
        not gonna happen anytime soon.

  2. Using the math provided by one of the people supporting this project as demonstrated a $1 million home will be close to a 10 percent tax 50,000 to septic $20,000 to housing bank $20,000 to land bank. The money grab is never ending by those who are looking out for us! What a joke.

    • Does that mean that “Islanders” are a joke?
      5% for septic is cheap

      The Island has never been good at accommodating the financially challenged.
      That is why your place is worth so much more than you paid for it.
      Stop the jokes, step in to a leadership position and Right all of the island’s humor.

      • Ok, then just provide sewer for people to tie into. Its not rocket science. Lets join 21st century infrastructure. This mickey mouse job with “enhanced septic” systems is the biggest joke.

Comments are closed.