Estuaries and salt ponds on the Vineyard will need to continue to be monitored for water quality management, even if water quality has improved compared with 2021.
That’s a takeaway from a presentation from Roland Samimy, a research manager from the University of Massachusetts Dartmouth School for Marine Science and Technology.
Samimy presented the health of estuaries and salt ponds on the Island with the Martha’s Vineyard Water Alliance on Thursday, April 20.
The presentation was primarily based on water sampling done during the summer of 2022.
“This is basically no different than in previous years: laying out the goals of the program, essentially [keeping] a handle on the nutrient-related water quality of all of the estuaries of the Vineyard and in each of the towns,” he said.
Various nutrients were tested during sampling, but nitrogen and chlorophyll were the main focus of Thursday’s presentation.
Most of the areas have thresholds for nitrogen and chlorophyll, determined by the Massachusetts Estuaries Project. That differs based on the water body’s environmental habitat, and what type of organisms are in the area, such as eelgrass.
The data sets Samimy presented ranged from 2016 to 2022. Most estuaries hovered around the threshold, while some have experienced spikes in certain years.
“I think that it’s really some regional, environmental condition,” Samimy said of the spikes. “Whether it was an overly cloudy summer, overly dry, whatever.”
Some bodies of water, or just certain testing sites, did not get tested during certain years since they were deemed healthy enough that annual tests were not necessary. Farm Pond in Oak Bluffs and Cape Pogue Bay and Pocha Pond in Edgartown were not tested in 2022, although they are being considered for testing this year.
Among the 10 tested estuaries, five in particular were listed with key consideration points by Samimy.
Lake Tashmoo in Tisbury will need to continue being monitored, since there was a “modest” nutrient enrichment, despite nitrogen and chlorophyll levels being lower in 2022 than 2021. Any changes to the inlet channel will need to be monitored to maintain effective flushing.
Lagoon Pond, which is in Tisbury and Oak Bluffs, has nitrogen levels that are lower than its threshold. As for chlorophyll levels, decreases were seen compared with 2021, and he said the pond is not in “impaired water” levels. Samimy made a point that annual testing will result in varying results.
Oak Bluffs Harbor’s main basin supports “relatively high and uniform water quality.” Meanwhile, Sunset Lake in Oak Bluffs had lower nutrient levels in 2022 than in 2021.
Sengekontacket Pond in Oak Bluffs had varying water-quality levels depending on test sites, with cleaner water throughout the main basin compared with tributary basins.
Katama Bay in Edgartown generally has high water quality, but it will need to be monitored due to the closure of the southern inlet.
Samimy had recommendations for the continued monitoring of the Vineyard’s bodies of water. Water-quality monitoring and testing should continue, but targeted sampling, some of which can be collected through automated sensors, should also take place. This would provide more data for environmental restoration efforts.
He recommended that information on how successful estuary openings are should also be collected, to allow a “data-based evolution of opening protocols to maximize positive impact on the ponds.” The number of pond openings should also be maximized for increased effectiveness, he recommended.
Samimy said that data from tests should be used to determine whether further testing is needed or reduced, based on threshold levels and actual nutrient levels.
