The Carlisle Mosquito Online

Friday, September 12, 2003


Is Greenough Pond a pond?

When is a pond not a pond? Answer: when it's part of a river or when parts of it have "riverine characteristics." So, is Greenough Pond a pond? This is the conundrum that two privately hired wetland engineers and six conservation commissioners, one of whom is also a hydroengineer, pondered at Town Hall the evening of September 4.

The reader might be excused for asking, "Who cares what you call it as long as it's there?" Luckily that question is easy to answer. First there are the numerous residents of Carlisle and Billerica who treasure our town's largest body of open water; second there are the members of the Carlisle Con-servation Commission (ConsCom) who are charged with preserving its beauty, and finally there is Carlisle resident Chris Fielding, who wants to build a house overlooking the scenic body of water.

The much tougher legal question first arose July 10, when engineers from Stamski and McNary presented Fielding's Notice of Intent to build on the site. The application gave no indication that the project might involve a riverine pond and thus might fall under the 1996 Massachusetts Rivers Act which requires a 200-foot buffer zone along riverine features and precludes building within the first hundred feet thereof. ConsCom Chair Tricia Smith immediately raised the issue of resource area delineation in general and the matter of riverine status in particular. The commission requested a peer review of the project and John Rockwood of EcoTec was subsequently tapped to perform the study.

The upshot of Rockwood's investigation as presented last week was that the pond has a narrow (5 to 3) preponderance of riverine charac-teristics. But because it is shown on the U.S. Geological Survey maps as a pond, it is presumed to be such, "unless the issuing local authority determines that the water body has primarily riverine characteristics." Thus, in this situation, only ConsCom could make that call. To help them make their decision Rockwood presented the scientific evidence, based on a legal precedent applied to Mill Pond in Bedford.

The peer reviewer noted first that historical documentation establishes the fact that Greenough Pond was formed in the 1930s by impoundment of Pages Brook as it meandered from Great Brook Farm, under Maple Street, into the impoundment, again joining the brook beyond the dam's spillways and on to the Concord River. Since unidirectional flow through a body of water is one of the major characteristics of a riverine pond as described by the DEP, Rockwood floated oranges through the Pages Brook entrance, monitoring them as they bobbed downstream and out into the pond. Once in the major body of water they slowed and soon stopped. Later, oranges tossed 40 feet out from the sluiceway failed to move in that direction, perhaps in part due to partial blockage by a beaver dam. By other accepted technical calculations, Rockwood had determined that the "total residence time" was 5.3 days, which is considered a riverine characteristic. Further calculations revealed the surface area of the pond to be 0.031 square miles, while its watershed area is 3.88 square miles, again a ratio that is considered riverine. The pond's shape · a three-pointed star · suggested a river, but the reviewer pointed out that the bottom lacks a channel, which strongly suggests it should be categorized as a pond.

Stamski and McNary engineer George Dimakarakos introduced a series of photographs showing substantial areas of green, which he said indicated thick vegetation, very suggestive of a pond. However, visual monitoring of the upstream portion by Rockwood, Administrator Sylvia Willard and ConsCom members showed strong flow but with an area of constriction at a point where a cart path had apparently existed in the past. Since the reviewer's job was to determine the technical facts and not to make a recommendation, Rockwood informed the commissioners that the decision was now up to them.

Commissioner Tom Brownrigg said he measured the flow at the major "inlet" at ten feet per minute. "To me, a pond with an inlet that is a flowing stream is riverine," he declared. When Willard again noted the presence of beaver activity, Commissioner Peter Burn commented that "beavers are a clear indication of moving water." Smith went on record as trusting more to the results of the oranges test, but also warned that surface facts don't always show what is going on underwater. "The question really is, where do we stop calling [the system] riverine and start calling it a pond, and then further on view it as a river again," she asked. Noting that the flow varies from day to day, Smith proposed that the commission use the cart path constriction as the limit of riverine activity, since it could serve as a clear- cut physical mark for conditioning future construction on the Fielding lot. The other commissioners concurred, and the motion carried. Areas upstream of that feature will therefore be subject to the Rivers Act. However, Fielding has one consolation. Because the lot was laid out before 1996, it is "grandfathered in" and he would be permitted to construct a house and septic system, if he so desires, within the first 100-foot buffer zone Dimakarakos said he will need time to digest the commission's action and decide what the impact will be on construction plans.

With the decision made and the applicants departed, Rockwood informed the commission that a Rivers Act specialist, when asked to review his findings, had recommended the solution finally adopted by the commission.

2003 The Carlisle Mosquito