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1996 Citizens Report: Cuttyhunk and Penikese Islands, Gosnold

Embayment: Cuttyhunk and Penikese Islands

Embayment and Watershed Characteristic

Two sites were monitored on the outermost islands of the Elizabeth Island chain--one site in Cuttyhunk Pond on Cuttyhunk Island and the other in the cove on Penikese Island. Both Islands are part of the town of Gosnold. This part of Buzzards Bay is well flushed and exposed to cleaner Atlantic Ocean waters offshore. Previous oceanographic studies of central Buzzards Bay have shown this part of Buzzards Bay to have the best water quality.

Penikese Island has a few farm animals and a summer population of less than 20. Cuttyhunk has a summer population of less than 500, but the harbor can accommodate several hundred boats. These demographics suggest that total nitrogen loading to the areas studied is modest, and the Penikese site in particular, with its wide open Cove, probably has the best water quality of any site in Buzzards Bay. Cuttyhunk Pond is interesting in that it is a shallow coastal lagoon that is not especially well flushed, and from a hydrographic sense, is similar to some of the less flushed embayments we have studied elsewhere in Buzzards Bay, but with considerably less nitrogen loading. Thus both stations are good "control sites" for our monitoring Program. Unfortunately, due to the remoteness of these sites, samples for nutrients and chlorophylls have not been collected, and we have only oxygen and other basic monitoring data for interpretation.

Cuttyhunk Harbor is also interesting in that it is closed to shellfishing in summer due to high fecal coliform levels. The source of these fecal inputs is believed to be principally from the many large power boats and yachts that pass through the harbor when travelling up and down the East Coast, with smaller contributions from failing septic systems, and additional inputs from wildlife. Boats are believed to be the principal source of fecal coliforms in part because no pump-out facilities are available on the island to remove sewage from the toilet holding tanks on the boats. It is believed that many of these boats illegally discharge both treated and untreated raw sewage directly into the harbor. The resident and town officials of the Islands recognized this pollution problem and sought state and federal funding for a pump-out facility. Funds for a mobile boat pump-out facility were received by the town last year, but ironically before the boat could be put into service it was returned to the state because of fears that the existence of a pump-out facility might attract even more visitors to the island!

Water Quality monitoring

Cuttyhunk Island at Fish Dock and Penikese Island were monitored for oxygen in all four years of our study. Secchi depths were measured in two out of the four years for each site. Oxygen concentrations at both monitoring sites were exceptionally good, with values typically ranging from 85% oxygen saturation to 105% oxygen saturation. The range of oxygen saturation values during the course of the summer were small compared to other more eutrophic Buzzards Bay embayments. The mean summertime oxygen saturations of the lowest 33% of values were all above 87% saturation at both sites. To put this in perspective, both sites would have scored a perfect "100" in 2 out 4 years for the oxygen score in the Eutrophication Index.

The water transparency data (secchi disk depth) for these sites was not as exceptional as the oxygen saturation data. Still, the mean summertime water transparency for Penikese (1.9 and 2.4 meters in the two years observed) and Cuttyhunk Pond (2.5, 2.9 and 2.1 meters in the three years observed) were far better than most Buzzards bay embayments.

Nitrogen Management needs

Penikese Island does not require any nitrogen management. Most of the homes on Cuttyhunk Island (except the ones near Cuttyhunk Pond) are connected to a sewer line that discharges raw sewage into Vineyard Sound. To the best of our knowledge, this is the only remaining discharge of raw sewage into Massachusetts coastal waters. The Buzzards Bay NEP has not conducted a nitrogen loading analysis for Cuttyhunk Pond, but the authors believe that it is unlikely that nitrogen management action is required. The discharge of sewage from boats into the harbor, however, will remain an important human health concern and will continue to contribute to shellfish bed closures. It would be interesting to collect water samples for nitrogen analysis at these sites for comparison to more eutrophic embayments in Buzzards Bay.

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