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What's Killing Our Ponds?


Algae in the Edgartown Great Pond 2008

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, also depend on healthy ponds and points out 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 comes from wastewater, typically septic systems. Lawn fertilizer is usually the second largest contributor, with  agriculture and stormwater runoff providing additional nitrogen loads. (While a significant amount of nitrogen  also comes from acid rain carried mostly from coal  burning plants in the Midwest, this is an l 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 that can also improve a coastal pond’s ability to utilize nitrogen without going beyond its loading capacity. This is accomplished by adjusting the flushing and circulation patterns of the pond. These options include dredging, and breaching totally enclosed ponds such as the Edgartown and Tisbury Great Ponds. However, these measures can often be difficult 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. Any changes  for the future will involve an Island-wide awareness of the problems and an understanding of the solutions. The Vineyard Conservation Society is working alongside  the Martha’s Vineyard Commission,  local watershed associations, shellfish officers, and other conservation organizations to try and stay ahead of the curve. The Massachusetts Estuaries Project will complete the robust science that will determine the nitrogen assimilative capacity of all the Island ponds within the next year. 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.