West Tisbury ponds need attention

By Dan Cabot - May 11, 2006

At their regular meeting last week, the West Tisbury selectmen discussed James Pond and the Old Mill Pond, both of which are in need of attention. Bill Wilcox, MVC biologist, has been studying both ponds and reported to the selectmen in separate presentations.

An ad hoc committee on James Pond - made up of Mr. Wilcox, five riparian owners, the town shellfish constables Tom Osmers and Ray Gale, members of the conservation commission (ConCom), and others - has been meeting since January 2005. Mr. Wilcox reported to the selectmen on recommendations made by the committee as of May 3. Their primary recommendation is that the pond be managed as a herring fishery.

James Pond, which has a narrow and winding opening to Vineyard Sound at Lamberts Cove beach, has for many years suffered from an insufficient exchange of sea water. Committee member Bob Woodruff described it as eutrophic and oxygen-starved. If any soft-shell clams remain in the pond, they are unsafe to eat because of water pollution, and the pond has been closed to shellfishing since 1997. Always a bit fragrant, in the summer of 2004 James Pond produced unusually large blooms of algae, which piled up malodorously on the leeward shore. Although the riparian owners once had a permit to open the pond to the sea, it lapsed in the 1990's. Nevertheless, individuals have from time to time acted on their own to open the channel, and a shallow stream has remained open for about a year.

Managed as a herring resource, the pond could be opened in the spring, when herring return to spawn, and again in the late summer, when the juvenile herring return to the sea. It is doubtful that in the short term large numbers of herring would return to James Pond, partly because of pressure from offshore fisheries on the herring stock. However, diligent management might eventually succeed, and in the meantime the pond would again become hospitable to clams and possibly blue-claw crabs and oysters, and in addition be a cleaner and more attractive feature of the neighborhood, according to Mr. Wilcox.

The committee recommends that West Tisbury shellfish constable Tom Osmers, in his capacity as herring constable, be responsible for opening the pond and arrange for volunteer labor to do the work with shovels and hand tools only. The ad hoc committee recommends that a notice of intent should be filed with the ConCom, who would issue an order of conditions for the openings. At the moment, no dredging is recommended, though Mr. Wilcox said that straightening the channel might be considered in the future, because the long, winding channel exposes herring to ospreys and other predators.

The selectmen were generally in favor of the project. Glenn Hearn said that steps should be taken "the sooner, the better." Jeffrey "Skipper" Manter cautioned that the committee should work more closely with the other riparian owners (there are about 20). Mr. Wilcox will draft a letter to the riparian owners.

The Old Mill Pond

The Mill Pond has come to the attention of the selectmen in the past few years because it has become choked with silt and plant growth, less visually attractive and less hospitable to the trout which are stocked there. The selectmen asked Mr. Wilcox several months ago to advise them. This was his second report on the Mill Pond.

Mr. Wilcox explained that the Mill Pond, like all the ponds on the Mill Brook and the Tiasquam River (which empty into Tisbury Great Pond), serves a valuable function in protecting the great pond by trapping nutrients flowing down stream, which would otherwise flow directly into the great pond and produce levels of plant growth unhealthy to fish and shellfish. In the chains of ponds along both the Mill Brook and the Tiasquam, nutrients like nitrogen and phosphorus settle to the bottom in front of the dams, where they can be taken up by plants. The deeper the pond, the longer the water stays in the pond and the more efficient the nutrient uptake from the water.

However, it is the nature of all ponds to fill up with silt and other materials, which are in time washed into the brooks that flow out of the ponds. As the ponds become shallow, water flows more quickly to the outlets rather than circulating within the pond, more sunlight reaches the bottom, promoting rooted plants, which in turn trap more silt, and the ponds lose their effectiveness as nutrient traps. This is happening at a time when more habitation is producing more nutrients in the runoff into the brooks.

Mr. Manter recalled that the Mill Pond was dredged twice in his lifetime. Maria McFarland of the ConCom reminded him that that dredging was done at a time when permits were not needed. Present state and local regulations make permitting expensive and difficult. Mr. Wilcox felt that a town would have an advantage over an individual in such an application.

Chairman of selectman John Early asked if the selectmen should be looking at all the ponds on the streams as an ecosystem, rather than considering only the Mill Pond. Mr. Wilcox answered in the affirmative, but added that the Mill Pond could be a kind of a test case. In a printed handout he wrote, "Several Cape towns are looking at deepening fresh [water] ponds to increase nutrient retention and offset nitrogen loading in coastal ponds. . . . It is possible that deepening one or more of the ponds on the Mill Brook and possibly one or more on the Tiasquam may be a cost-effective way to reduce nitrogen loading from this portion of the watershed."

Mr. Manter suggested that perhaps Community Preservation Act (CPA) funds or other grant funds could be used for such a project.

Although Mr. Manter said he is in favor of dredging, there was agreement that getting permits for dredging ponds will be a time-consuming and expensive process. The Department of Environmental Protection (DEP) and perhaps even the Army Corps of Engineers will have to be consulted, as well as the local conservation commission.

In the meantime, Mr. Wilcox suggested temporary remedies to the choking of the Mill Pond, including hand-harvesting of weeds, a winter drawdown of the pond, and the application of herbicides. All of these would also require ConCom approval.

Mr. Early proposed that the selectmen get together with the ConCom to formulate an action plan based on Mr. Wilcox's recommendations.