Septic runoff threatens Hummock Pond

PHOTO BY PETER B. BRACE Hummock Pond: Look, but don't touch! Health Inspector Richard Ray wants to clean up Hummock Pond. Hummock Pond is dirty.

It is so dirty with septic system runoff and gray water contamination that the town closed the pond this past summer because of toxic blue-green algae blooms and is proposing a set of septic system inspection and repair regulations similar to those that apply to the watersheds of Nantucket and Madaket harbors. In short, opening the pond twice a year to the ocean, to both drain it of harmful compounds and provide its low-salinity inhabitants with fresh salt water, is not sufficient enough to keep the pond clean.

"There's a significant amount of excess nutrients in the Head of Hummock Pond. That includes both phosphates and nitrates from both fertilizers and from septic systems," said Dr. Sarah Oktay, managing director of the UMass Boston Nantucket Field Station, whose water quality testing wells around this pond revealed its degraded water levels this year.

The town closed the pond at the behest of Health Inspector Richard Ray, Oktay and members of the Hummock Pond Association because of a neurotoxin produced by blue-green algae found in the pond called Microcystis aeruginosa and Anabaena circinalis — both also known as cyanobacteria — that is toxic to humans and animals. Ingestion or just simply getting splashed with the pond's water can cause intestinal disorders and skin irritations, respectively, and death, depending on the concentration of the toxin that is ingested.

To avoid future closings, and clean up the pond's other pollution coming from failing septic systems, the Hummock Pond Association proposes that it, its abutters, the Nantucket Conservation Foundation, the Conservation Commission, the Marine & Coastal Resources Department, the Board of Health, the Nantucket Land Council and the UMass Field Station write a watershed management plan for the pond. Additionally, this group would hire a professional pond management company to develop a short-term remediation plan for the pond. The group wants to continue Oktay's water quality sampling and analysis program to keep tabs on the health of the pond.

"We believe that the problems in Hummock Pond are obvious — excessive nutrients from septic systems and surface runoff," said Hummock Association president Bob Williams in part of his Oct. 7 letter to town manager Libby Gibson. "It is now time to reverse the downward trend in water quality in Hummock Pond."

Part of that solution will be regulations requiring property owners abutting the pond to have their septic systems inspected and if need be, repaired or replaced in the same manner that the town is cleaning up Nantucket and Madaket harbors; by requiring those closest to the water to get their inspections and repairs done first, while giving those living further inland more time to meet these proposed requirements.

"We're going to do it exactly that way," Ray said. "The one decent thing here is that a failing septic system emits both nitrates and phosphates, so we're going to take care of both with the repairs. We know pretty much what the source is."

In February 2010, Ray hopes to establish a water quality zone, also known as a watershed, for Hummock Pond through a regulation that the Board of Health would need to review and approve. In April or May, Ray wants to have that board enact regulations requiring mandatory inspections of septic systems within specified time frames for near-water and inland zones within the new watershed.

Ray stressed that although the blue-green algae bloom alerted the town to the pollution problems in Hummock Pond, his efforts to clean up this pond are much broader and are aimed at its long-term health.

"I'm not going to be focusing on blue-green algae," he said. "I'm going to be focusing on limiting nutrients [going into the pond]. We're hopefully going to get somebody to do some testing in the spring, but this is all in the planning stages right now." I