Text of the pond management statement sent to Peter Boyer, Town Administrator, for consideration as Town policy.

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Policy for the Management of Oyster Pond

Introduction

OPET has distributed a survey form to all the property owners in the Oyster Pond watershed and to other interested parties. The results of this survey indicate two interesting facts, namely: 1) the interest of the interviewees is weighted heavily towards aesthetics as their primary concern regarding the Pond and 2) there is no strong polarization of opinion as to how the Pond should be managed to accomplish the desired end.

To help formulate a plan of action for the management of the Pond, there have been ongoing studies of the Pond since 1987 by the laboratory of Dr. Brian Howes of the Woods Hole Oceanographic Institution, sponsored equally by the Town of Falmouth and the National Sea Grant program. This study is broadly known as the Falmouth Pond Watchers program. In addition, there is data available from the work of Dr. K.O. Emery dating from the late sixties.

These studies point to the:

• Goal: that we should manage the Pond to try to approach, as closely as possible, the pre-1987-88 conditions when the Pond was in a more healthy condition.

• Problems: Oyster Pond is a pair of flooded kettle holes whose depth in excess of six meters makes it somewhat unusual as a coastal pond, giving it unique problems and suggesting unique solutions for good management. Its comparatively long distance from Vineyard Sound makes any water communication between the two bodies potentially very expensive and difficult to maintain.

  Because of the depth of the Pond, the constant inflow of fresh water and the periodic inflow of salt water, there is a consequent stratification of heavier salt water and lighter brackish water. In the summer, there is not enough wind mixing to get oxygenated water into the heavier salt water. Because of this stratification, the studies have shown, only approximately 35% of the bottom of the Pond has oxygen in summer. This kills the associated bottom life on 65% of the bottom and has a deleterious effect on the health of the Pond's animal and plant life.

  The Pond has an inordinately high nitrogen content, reduction of which is the second problem (although, by no means, secondary) which must be tackled after stratification.

• Solutions: To reduce the stratification problem, two solutions have been proposed:

1. Cut a channel across the bike path and Surf Drive into the Pond to give the necessary water exchange from tidal action so the stratification would be eliminated and turn Oyster Pond into a salt pond. Needless to say, the cost to build and maintain such a channel would be extremely high and the permits would be difficult to obtain.
2. Keep the Pond as a brackish pond (2-4 ppt) similar to the pre 1987-88 conditions. Reduce the salt content so the depth of the brackish water increases until the top four plus meters, separated from the deeper salt water, stays oxygenated all the time. If this can be accomplished, there should be an increase in constant oxygenated bottom area such that approximately 80% of the bottom will always be oxygenated. This solution could be accomplished by installing an adjustable height weir (to control salinity), with a herring run/fish ladder, to control the depth of the Pond and prevent tidal action from bringing in salt water on a daily basis. It is understood that hurricane action will periodically charge the Pond with some salt water but this is acceptable. The constant inflow of underground fresh water and rain water would normally cause a flow over the top of the weir taking salt with it. This becomes the mechanism for removing salt from the Pond. It is believed that the cost of this solution would be very much lower than solution number 1. In any event, the low cost of this option and its reversibility do not preclude adopting solution number 1 or other options after several years.

OPET endorses the second Proposal

Implementation of Pond management is suggested for three phases:

• Phase I: Make no attempt through dredging, enlarging of the culvert under Surf Drive or any other means to increase the interchange of water between Oyster Pond and Vineyard Sound. Our goal is to keep the salt water out? This phase has been partially implemented for the past two years.
• Phase II: Design and construct an adjustable rising weir and a herring run/fish ladder based on the requirements which Dr. Brian Howes, backed by his current seven years of research on this Pond, will be prepared to furnish as consultant to the engineers. OPET will be pleased to offer whatever assistance it can.

  The problem of the high coliform bacteria counts in the summer (probably arising from a combination of surface water run-off, faulty septic systems and water fowl population) needs to be addressed in this phase by identifying which contributor is the source(s). If the coliform is human, then correction must be implemented.

• Phase III: When the plan is put into operation, its results should be monitored for effectiveness. OPET's position is flexible, and it is prepared to suggest change if solution 2 doesn't work as expected. OPET also feels, however that the solution needs to be given a chance of several years to work before any new plan should be contemplated. It is almost certain that nitrogen levels will have to be reduced, but the evaluation of how much must wait until the stratification problem is reduced.

Adopted 9/24/95

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