State of The Pond Report 2019

Charles Carson has written the new Sengekontacket 2019 State of the Pond report.

 

Working with local and Commonwealth officials, the Friends of Sengekontacket has monitored the health of Sengekontacket Pond and its barrier beaches for over 40 years. The recent SMAST and MVC report, “Water Quality Monitoring and Assessment of the Martha’s Vineyard Island Wide Estuaries and Salt Ponds 2018 (Year 3 of 3)” Jan, 2019 provided FoS with high quality data and scientific assessment and is integrated into this report. The scientific team classified the entire Sengekontacket water basin as “High Quality”, but the pond as “Somewhat Impaired”. The Eutrophication health Index of the water in the Major’s Cove, Trapps Pond and Ocean Heights secondary inlets is classified as only Moderate and those inlets continue to be the focus of concern and future testing.

How good is good?

A body of water requires nitrogen for health and aquatic plant growth. An excess of nitrogen results in a heavy growth of the biomass, depletion of oxygen in the water column, and the loss of essential aquatic habitat. The Commonwealth recommended a maximum TN (Total Nitrogen) reading of 0.35mg/L to define the upper limit of good pond health. When the MEP report was published in 2011, the range of TN readings in the pond ranged from 0.21kg/L to 0.61mg/L. The highest TN readings were at Majors Cove (0.611mg/L) and at the Southern end of the Trapps Pond (0.601mg/L) culvert on Beach Road. The new 2016, 2017 and 2018 and prior readings are similar.

Mitigation

In a nitrogen mitigation effort, Edgartown and Oaks Bluffs have spread millions of oysters every year in the pond with a heavy concentration in Majors Cove. Oysters and other shellfish consume nitrogen. Similar programs have been used successfully throughout the world to reduce unacceptable nitrogen. During the winter of 2014-2015, the impressive and cooperative efforts of the Vineyard towns and interested parties have resulted in an Island wide adoption of fertilizer regulations and applicator training.

 

Continued efforts should include:

  • Improved flushing of the secondary inlets in order to maintain the existing high water quality between the two main inlets and the bulk of the Pond area. The channel of the Little Bridge should never be allowed to become restricted or totally closed, It must be a top priority of the Town of Oak Bluffs to keep the channel of the Little Bridge dredged and open. If we had to pick a key to Pond health, it would be flushing.

  • The dredging of Majors Cove.

  • Encouraging the Cow Bay Association to work cooperatively with the Commonwealth to reduce or eliminate nitrogen pollution emanating from the Cow Bay Association properties.

  • Encouraging the towns to require nitrogen reduction septic systems for all replacement and new septic systems within the Sengekontacket Pond watershed.