Nantucket Harbor among the cleanest in the state
BY PETER B. BRACE INDEPENDENT WRITER
Nantucket Harbor is nearly at the point of being the cleanest harbor in the state, if not for nitrogen-loading caused by development around its shores, rain and airborne particles.

That assessment comes from Dr. Brian Howes, a professor at the University of Massachusetts School of Marine Science and Technology (SMAST) who leads the Massachusetts Estuaries Protect, an analysis of 89 estuaries, harbors and bays in southeastern Massachusetts.

For each body of water, SMAST is kicking out a report on its health, causes of degradation and solutions for reaching a natural/human world equilibrium. Nantucket's and Sesachacha Pond's reports, given orally on Nantucket at special information session at the high school on Aug. 30, were among the first round of reports that SMAST released.

Howes said that Nantucket Harbor could easily be pulled back from the brink of becoming significantly polluted through several measures easier to accomplish because the island's harbors and ponds are all under one town government. And he commended the town for its septic regulations requiring inspections of all harbor watershed septic systems and repairs of faulty ones, and for having much of the populated areas of the island already sewered.

"Especially for Nantucket, it's one municipality; you guys own the watershed, so it is totally within your control to move forward and do it," said Howes. "So it really comes down to internal town issues of how you prioritize things."

Quoting from Nantucket Harbors report, Howes said that Nantucket needs to maintain and improve harbor circulation through dredging, care for and rebuild its wetlands, which remove nutrients from the harbor, step up educational efforts on the dangers of excessive fertilization and explore the use of centralized and decentralized septic systems.

The report said that 70 percent of the nitrogen going into Nantucket Harbor is beyond Nantucket's control, reaching Nantucket water bodies in rainfall and as dust particles from air pollution. The rest comes from faulty septic systems, fertilizers and runoff.

Should the town leap into action to completely restore the health of Nantucket Harbor, Howes said visible results are possible in three to five years.

What is likely to be the only solution for cleaning up Sesachacha Pond is an additional opening of this Quidnet pond to the existing spring and fall water-letting schedule performed each year. Howes expressed astonishment at how polluted Sesachacha was, but then said that it was not because of nutrient-loading from fertilizers and leaky septic systems since much of the pond is surrounded by undeveloped land, but low salinity and oxygen levels.

"It's highly eutrophic, that's why you have the algae blooms," said Howes.

Marine & Coastal Resources had planned a third move this year, one that would have happened probably in August, but Town Biologist Keith Conant scrapped the idea because colder weather and high winds in the second half of the month helped to stir up the pond and boost its oxygen content. With Howes' recommendation, a third opening is likely in 2008

What the town is waiting for from SMAST, is the total maximum daily load number (TMDL) for Nantucket Harbor and Sesachacha Pond based on water quality data collected by the town and analyzed by the project's staff. The TMDL number represents the total amount of nutrients - sewage, fertilizer and other toxic runoff - that a given body of water can absorb before dipping below its ability to sustain life and into the realm of beach closures.

Nantucket's Planning Board and Conservation Commission will be able to use that number to limit the number of bedrooms per new house as well as the size,

type and location. I