Edgartown Great Pond received an excellent tidal flush for 20+ days in April, refreshing the Pond with seawater.
EGP cut open and flowing on April 8, 2023.

It has been a while since our latest cut update, so we wanted to celebrate the smashing success of the April cut which stayed open and tidal for 20+ days following winter dredging by the Town of Edgartown. This is excellent news for Edgartown Great Pond and all the life within its depths.

We have Edgartown Shellfish Constable, Rob Morrison to thank for this stellar start to the season. The cut flushed every region and cove both the Pond with salty, cool, clean, and oxygen-rich seawater. Still now in August, the salinity throughout the Pond is in the upper teens ~17-19 ppt (parts per thousand). For reference, the Atlantic Ocean is approximately 33 ppt and eelgrass prefers salinity above 15 ppt but can tolerate salinities as low as 10 ppt for short periods of time.

The question on everyone’s mind seems to be whether or not there will be a summer cut of Edgartown Great Pond. A lot of factors weigh into the Town of Edgartown’s decision to cut the Pond. We are very lucky that the Town’s decision rests on the capable shoulders of biologist and Shellfish Constable, Rob Morrison. Rob uses all the scientific tools and data at his disposal and tends to look towards moon tides to optimize the effectiveness of a cut. The next New Moon is August 16th, and the Full Moon is August 30th. All the conditions, sea state, moon tide, wind, elevation, and many factors must come together for an optimal cut.

For a summer cut to occur, the Pond elevation has to be high going into the summer and the precipitation needs to exceed the evaporation. GPF has been tracking the elevation of EGP and it has been staying at approximately 3 feet above Mean Sea Level (MSL). Successful cuts occur when EGP elevation meets or exceeds 3.5 feet above MSL.

Summer cuts are so fun to see and explore, but the consequences of an ill-timed cut are severe and may outweigh the fun. During a successful cut, the Pond must drain and then it must become tidal to flush all coves and corners of EGP with cool, clean, clear, salty, and oxygenated seawater. If the Pond is cut and drains but the tidal flush does not occur, the Pond would be shallow and heat up, reducing the water quality and endangering all the life within it.

The elevation of Edgartown Great Pond has been staying ~3 feet above Mean Sea Level (MSL).