Martha’s Vineyard is blessed with a wondrous group of coastal ponds that rim the entire Island. From Squibnocket Pond on the western shore to Pocha Pond in the east, these special natural resources offer fishing, shellfishing, water sports and natural beauty. As a group, they represent the Vineyard’s greatest environmental asset. The tourism and shellfishing industries, as well as property values, depend on healthy ponds. This demonstrates the natural linkage between the economy and the environment when it comes to their protection.
Unfortunately, most of our coastal ponds are already experiencing degraded water quality and habitat stress. This is due mostly to an increase in the amount of nitrogen that is discharged within each pond’s watershed. Nitrogen is carried by groundwater and eventually drains to the ponds. While a certain amount of nitrogen is necessary to support the life of the pond, too much is problematic. This over loading of nitrogen causes a disappearance of important sea grasses and an increase in nuisance algae, which, depending on the severity of the problem, can lead to anything from aesthetic issues to a diminished shellfish crop.
Most of the nitrogen that is generated locally comes from wastewater, typically septic systems. Lawn fertilizer is usually the second largest contributor, with agriculture and stormwater runoff providing additional nitrogen loads. (Unfortunately, a significant amount of nitrogen also comes from acid rain originating largely from coal burning plants in the Midwest, this is an issue that must be dealt with at state and national levels.) De-nitrifying septic systems, reduced fertilizer use or the use of organic fertilizer, sewering and the remediation of storm water runoff are some of the standard solutions. In addition, there are physical remedies -- flushing and adjusting the circulation patterns of the pond -- that can also improve a coastal pond’s ability to utilize nitrogen without going beyond its loading capacity. Options here include dredging and breaching totally enclosed ponds such as the Edgartown and Tisbury Great Ponds. However, these measures can often be difficult and expensive to manage and sustain.
Given the importance of these special resources to the quality of Island life, we cannot allow this downward trend in water quality to continue. The Vineyard Conservation Society is working alongside the Martha’s Vineyard Commission, local watershed associations, shellfish officers, and other conservation organizations to try to build an Island-wide awareness of the problems and an understanding of the solutions. The Massachusetts Estuaries Project is working to understand and apply the relevant science to help planners create practical management plans for the ponds. Then, the hardest part will begin, funding and managing the necessary actions to preserve our ponds.
VCS understands the risk we take by not acting decisively. For this reason, we have launched the “Clean Water Initiative” intended to educate Vineyarders about the problem, the reasons for it, and what can be done on both an individual level at home, and on a community level to support water quality programs. We are convinced that if the general public is properly advised, the declining health of our ponds can be turned around.
Visit the MV Shellfish Group website and view the Island Blue Pages: a Guide to Protecting Martha’s Vineyard Waters.
A watershed map of the Island, prepared by the M.V. Land Bank (click to enlarge)
Some important water definitions
Aquifer: Underground sediments saturated with water.
Watershed: Area of land in which all water, whether above or below the ground,
is constantly moving downhill towards the same body of water. A watershed may
include thousands of acres and water may travel many miles from the highest
elevation point to the body of water at or near sea level.
Runoff: Downhill movement of rainfall, over impervious surfaces or slowly permeable
soils, to a discharge point: a wetland, a fresh or coastal pond, or the ocean.
Groundwater: Water stored in or moving through the aquifer.
Recharge: Process where precipitation moves through the soil and reaches the
groundwater, replenishing the aquifer.
On July 21, 2010, the Vineyard Conservation Society joined with the Towns of Tisbury and Oak Bluffs to chart a course to reverse the ongoing deterioration of our coastal ponds. This second “Ponds in Peril” forum featured engineer Mike Giggey, who outlined the scope of the challenge and the actions needed to turn things around.
On Martha’s Vineyard, nitrogen from individual septic systems travels “downhill” in groundwater to our ponds, causing explosive growth of algae that consumes oxygen, blocks sunlight and starves marine habitats. Remedying the nitrogen problem can be fairly rapid when densely-settled areas are removed from septic systems and tied into central sewage treatment facilities that remove nitrogen. But the cost is high.The conclusions were surprising and in some respects alarming:
The most cost-effective way to deal with the Island’s wastewater treatment needs is to continue to rely on individual residential “Title 5” septic systems, while at the same time addressing contamination of our coastal ponds through precisely-targeted sewering of the most densely-developed areas.
Relying on Title 5 will require proper management, however. This starts with towns, either individually or through a regional entity like the county, developing a common onsite wastewater management program with actions like creating a common database for inventorying all their septic systems and tracking inspections.
Historically, promoting economic development on MV appears to be the primary reason for developing sewer infrastructure. Nearly three-quarters of the Island’s 57,000 acres falls within watersheds feeding our nitrogen sensitive coastal ponds (see Land Bank map above). But most (>70%) of the wastewater treated in our sewage treatment facilities originates outside the sensitive coastal ponds watersheds.
The attention of leaders and voters must now turn to protecting our ponds and natural resources as a reason for connecting densely developed neighborhoods to existing sewer infrastructure. But it also must be part of a coordinated and comprehensive wastewater planning process.
In order to protect our nitrogen sensitive ponds, we should be collecting and centrally treating almost three times as much wastewater (2.3x) as is currently treated. Some 14,000 parcels of land have been developed on MV, each with septic systems, many in thickly settled neighborhoods like Ocean Heights on Sengekontacket Pond. Targeting those areas for sewering is a priority.
But that is the easy part. In the future, that number will jump even higher, as will the associated costs. Today, the cost to address the wastewater we need to be collecting and treating Island-wide is in excess of $200 million. Towns and the county need to acknowledge this fact and commit to collaboration across watershed boundaries so that the most affordable solutions are identified and implemented.
On the Vineyard, a mix of collection and treatment technologies will be used, including cluster systems (treating less than 10,000 gallons/day), satellite systems (like the one servicing the airport and business park), and conventional “centralized” facilities like the ones in Edgartown, Tisbury, and Oak Bluffs.
Economies of scale apply when it comes to wastewater treatment. In determining the cost of collection, treatment, transportation and disposal, the larger the annual flow, the less it costs to treat. But while “big is better” with wastewater treatment solutions, town planning boards and wastewater committees need to put into place “sewer use“ or “no-net-growth” regulations to prevent new sewer capacity from ushering in unchecked growth. That is, building sewers can unleash demand that doesn’t exist currently. A “growth neutral” wastewater plan must be put into place to ensure this doesn’t happen.
Also, with any collection system, an important question is WHERE the treated effluent is disposed of. “Benign” disposal areas are those outside the watersheds of the nitrogen sensitive ponds.
Installing sewer pipe is expensive, representing more than 60% of the total cost of centralized treatment. So a spectrum of other strategies will need to be part of the solution. Managing Fertilizer use is an important tool for addressing existing nitrogen inputs. During the 2014 Town Meetings, voters of all six Island towns approved a new bylaw that would regulate the sale and use of lawn fertilizer, which is a good first step to reducing nitrogen from lawn runoff.
Unfortunately, human urine represents about 80% of the nitrogen problem, so a thorough solution will require creative thinking beyond improving our lawn care ethics. Pilot projects involving urine diverting toilets should be encouraged, as is already happening in Falmouth.
Current sewering needs can be accommodated at existing treatment facilities with modest modification and expansion. Planning for that expansion needs to occur. Responsibility for that task should rest with a regional public entity, specifically the county, or with a new regional nutrient management district. Town leaders need to open discussions with county government and MVC about overseeing wastewater facilities planning.
The key to successfully implementing such a regional wastewater plan will be for the towns to empower the regional entity with authority to make regulations impacting community growth. This means authorizing constraints on real estate development by passing a “No Net Nitrogen” policy, where all development must offset nitrogen produced, either on-site or through acquisition of land off-site dedicated to open space.
The more difficult part is addressing the impacts of future growth that will likely occur within our sensitive watersheds in the years ahead. Based on development allowed under zoning rules, the MV Commission estimated that Martha’s Vineyard could experience a 55% increase in wastewater flow, to more than 4 million gallons per day. Mike Giggey said, “I find this shockingly high.”
Part of that growth will be in the form of “re-development” where an already developed parcel will become more intensively used, generating more wastewater.
Interestingly, in Chilmark Pond the largest source of nitrogen is atmospheric deposition from industrial air pollutants originating in the Midwest. Town leaders need to work with legislators to examine the feasibility of curtailing pollution at its source. Local mitigation by improving circulation and flushing should also be studied.
In the years ahead, the Mass Estuaries Project (MEP) will determine the nitrogen “assimilative capacities” for the Island ponds, which will help refine the scope of the nitrogen problem and the costs associated with remedying it.