Since 1983, the Massachusetts Department of Environmental Protection and the Town of Nantucket Conservation Commission have determined that activities within the one-hundred-foot buffer zone pose a significant risk to the health of wetland resource areas. Therefore, a request for determination of applicability or notice of intent must be filed for all activities proposed within the buffer zone to these resource areas.
The role that a protective buffer zone plays in the maintenance of healthy resource areas has been discussed in scientific literature for decades. Documentation exists that shows (Omernik 1977) a direct relationship in increased nitrogen and phosphorous loading to wetlands and water bodies as their adjacent watersheds are cleared. Water quality can be better maintained if undisturbed protective buffer strips are maintained and preserved along surface water bodies. Adverse impacts from sediment erosion and transport are also minimized with the maintenance of an undisturbed buffer between the site development and the wetland resource area. Further, the transitional assemblage of trees, shrubs, and ground cover found in undisturbed buffer zones has been found significant to the support of a greater number of native wildlife species and fauna (biodiversity) in the interior of resource areas which they border.
Although the Town of Nantucket Wetlands Protection Bylaw (Chapter 136, Wetlands, of the Code of the Town of Nantucket) defines significant cumulative effects as criteria for denying a project, permit-level activities (i.e., site disturbance) are difficult to measure on a scale of cumulative impacts (watersheds). Cumulative effects result from individually minor but collectively significant actions taking place over a period of time. The level of information required and techniques employed for individual permit review are generally not sufficiently definitive to accurately assess potentially significant cumulative impacts, even though it may be clear that the collective impact of many such activities could adversely affect a wetland resource area. The best protection against cumulative impacts is the maintenance and preservation of an undisturbed buffer zone.
A. 
Based on available information, the Commission has determined that, generally, maintenance of a twenty-five-foot undisturbed vegetative buffer zone and a fifty-foot structure-free buffer zone will serve to protect most wetland resource areas from adverse impacts related to development elsewhere within the buffer zone.
B. 
Work proposed within 50 feet of a wetland resource area shall require the filing of a notice of intent. Work proposed outside of the fifty-foot setback may be eligible for a negative determination of applicability, provided the proposed work does not fall within an area mapped as rare or significant habitat or as a vernal pool by appropriate state and/or local agencies or departments; does not border on an outstanding resource area; provides erosion and sediment controls; and establishes a work limit at or greater than 50 feet from any wetland resource area, exclusive of land subject to coastal storm flowage.
C. 
It sometimes is necessary to impose additional restrictions on activities within the one-hundred-foot buffer zone to prevent potential adverse effects on resource areas.