Sooner or later, the nitrogen pollution threatening the health of Martha’s Vineyard coastal ponds will affect us all. Some, because we swim, fish, kayak, or sail in the Island’s 27 saltwater or brackish ponds, or are lucky enough to live along the Island’s 290 miles of shoreline. Others, because our jobs are dependent on our visitor-based economy, and the ponds are an important part of what makes the Vineyard attractive. And all of us because we pay taxes and are, or should be, concerned about the hundreds of millions of dollars it could cost to solve this challenge and meet the requirements of the Clean Water Act.
In the next couple of years, discussion about this issue will be transitioning from concern and analysis, to making some pretty momentous decisions about what to do.
Fortunately for us, the Cape Cod Commission just completed the first phase of a multi-million dollar Water Quality Initiative, and next week CCC Executive Director Paul Niedzwiecki is coming to Martha’s Vineyard to share the results. This will give us a head start in our discussions about how best to proceed, from extending sewers and using alternative technologies, to regulatory reforms and monitoring. How can we minimize costs, and what are potential sources of financing?
Most of the so-called “manageable” portion of the excess nitrogen — that is, the part that doesn’t come from air pollution — is caused by wastewater, or to be more specific, urine being flushed down tens of thousands of toilets, getting into the groundwater, and flowing into the ponds.
About 64 percent of the Vineyard’s land area is made up of watersheds that drain into nitrogen-sensitive coastal ponds, either through runoff or groundwater flow. Excessive nitrogen over-fertilizes aquatic plants, resulting in odorous, unattractive ponds devoid of eelgrass, fish, and shellfish, adversely affecting the valuable tourist industry and coastal property values.
So what can we do to prevent excessive nitrogen from ruining the ecology of our coastal ponds? How can we prevent the nitrogen-laden wastewater from individual on-site residential septic systems in the watersheds of each pond from flowing through groundwater into our coastal waters? There are a variety of techniques available, but almost all are very costly.
Last year, the Island towns endorsed the lowest-hanging fruit, namely limits on the use of nitrogen fertilizer. That is just a small start. For some ponds, we can dilute the nitrogen by improving tidal flushing to the sea with widened inlets or more pond openings. And growing oysters and other shellfish can reduce nitrogen somewhat, though this is not yet recognized by the Department of Environmental Protection (DEP).
But the main solution will have to be treating the wastewater before the nitrogen reaches the pond. Nitrogen can be reduced at the source with techniques such as composting or urine-separating toilets, but it isn’t clear whether they would get broad public acceptance. Sewering and centralized treatment remove about 95 percent of the nitrogen, and have the advantage of being able to deal with pharmaceuticals and other newly emerging contaminants, but are only cost effective in high-density areas. On-site innovative alternative septic systems remove about 40-50 percent of the nitrogen compared to standard Title 5 systems, but this may not be enough for many watersheds. Both methods are costly to install and maintain.
We have enough of a problem dealing with the impacts of already existing development, but future growth will only exacerbate the problem. It might also make sense to consider board of health and zoning regulations that limit the number of bedrooms in a house, set limits on how much nitrogen a new project can generate, or require that the nitrogen generated by a development project in a critical watershed be offset with nitrogen reduction elsewhere in the watershed. The Martha’s Vineyard Commission (MVC) does this when it reviews Developments of Regional Impact (DRIs). Land acquisition for open space also reduces the generation of nitrogen.
The MVC has been working with Island towns for over a decade to do extensive water testing and land use modeling, which was used in the Commonwealth’s Massachusetts Estuaries Project (MEP), which is in the process of preparing comprehensive reports for each of our watersheds. Some have been released and more are on the way. Town officials, committees with representatives of the towns in a watershed, and pond associations are now grappling with how to use the MEP reports to come up with solutions.
As part of its Water Quality Plan, the Cape Cod Commission developed a number of tools that allow technical experts and the general public to compare various wastewater treatment options for each neighborhood or watershed, and to track the parcel-specific wastewater loads. They also had two teams working on alternative approaches. One focused on traditional collection systems of sewers and centralized treatment plants. The other looked at non-traditional or enhanced natural systems, starting with the premise that collection systems should be avoided or minimized to the greatest extent possible.
Given the enormous future financial burden of dealing with this problem, we need to find the most cost-effective techniques. Many of the techniques and conclusions of the Cape’s Water Quality Study are likely to be applicable to Martha’s Vineyard, so we should take full advantage of the work that was done by our neighbors on the Cape.
The public meeting on Smart Wastewater Management will be held on Thursday, November 20, at 5:30 pm at the Katharine Cornell Theatre in Vineyard Haven. Information about the Cape’s Water Quality Plan can be found at www.capecodcommission.org.
Mark London is executive director of the Martha’s Vineyard Commission.