ArcNews Online

Spring 2007
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GIS Provides Decision Support to National Recreation Area Stakeholders

Risks to Boston Harbor Islands Graphically Displayed

By Jennifer Bender Ferré, Ph.D.


  • Boat traffic is analyzed with ArcGIS Desktop.
  • ArcGIS Spatial Analyst identifies sensitive and vulnerable areas.
  • GIS tools aid decision makers in defining boat routes.

Federal GISThe Boston Harbor Islands National Recreation Area is a national park created in 1996 by an act of Congress and is made up of 34 islands near the Greater Boston shoreline. The park is designed to protect the islands through public/private decision making that takes into account overarching goals, such as improving access; providing education; and conserving, protecting, and managing the natural and cultural resources for public use and enjoyment of the islands. The legislation defined a new model wherein the National Park Service (NPS) owns none of the islands, and the park is funded through a partnership of federal, state, and local governments and the private sector.

To meet criteria in the enabling legislation, such as educating the public, visitation to the islands had to increase. The resulting rise in boat traffic likely impacts wake effects, nesting habitats, shellfish beds, water turbidity, changes in rocky/soft intertidal communities, pollution, and noise. Researchers from Boston University's Geography Department used GIS to better visualize the effects of this traffic and support decisions related to managing this area.

  click to enlarge
The shaded area indicates gathering areas for wintering waterfowl, such as American black ducks and mallards.

Understanding Nature

Though the park does not include the watershed surrounding the islands, the water and the islands are interdependent in ways that must be taken into account in developing an integrated management plan. The intertidal, coastal, adjacent ocean, and terrestrial island areas represent a complex and dynamic environment in which chemical, geological, biological, meteorological, and estuarine processes take place. These habitats are interlinked and should be considered a unified system; this underlying sea/land interaction is at the center of the ecological learning opportunity in the park.

The National Park Service has been directed to operate as a nonlandowning participant in the partnership with the responsibility, but not the authority, to make decisions directly related to the congressional mandate to achieve ecological, educational, recreational, and economic goals. Authority to determine policy and make decisions rests instead with each island owner. A 13-member body of representatives from public and nongovernmental organizations coordinates management. Furthermore, the Advisory Council has 28 members, including representatives of municipalities, education and cultural institutions, environmental organizations, business and commercial entities, and Native American interests. Members of the partnership are appointed by the Secretary of the Interior and the Advisory Council by the director of the National Park Service.

  click to enlarge
Ferry paths and shipping routes were mapped to better evaluate areas that are vulnerable to increased boat traffic (map sources: USGS, Woods Hole Oceanographic Institute, MassGIS).

An overview of environmental problems and governance structures in the park revealed specific management problems and challenges. Ecosystem management, an integrated approach to management that considers the entire ecosystem, is a necessary piece in the decision-making process. Linking marine governance to the paradigm of sustainable development based on an ecosystem approach requires the creation of new GIS tools.

Mapping Vulnerable Areas

Researchers used ArcGIS Desktop software—the NPS standard—and the ArcGIS Spatial Analyst extension to analyze the park and the impact of boat traffic. GIS is an ideal tool to support group-based decisions regarding boat traffic management in the area because it permits visualization of the complex ecological data and goals generated from the partnership. The maps displayed environmental concerns and their associated goals relative to increased boat traffic. The results enabled mapping and defining areas that are or potentially are sensitive and vulnerable.

The maps included information on turbidity, shellfish beds, salt marsh and eelgrass beds, multiple bird layers, and two intertidal layers. All these layers were built upon color orthodigital photos downloaded from Massachusetts Geographic Information System (MassGIS), with an overlay of a bathymetry layer from the National Oceanic and Atmospheric Administration. Of the nine layers mapped, four layers were analyzed in detail to illustrate the interconnectedness among measures. These measures underscored the complexity of the system because they were dependent on one another. They included turbidity, shoreline nesting habitat (tern productivity), and salt marsh.

These GIS maps used a simple algorithm to quantify the grid cell throughout locations in the Boston Harbor Islands area. Different layers and grids were assigned values based on partner-established criteria. The results were displayed as a raster or grid map.

The innovation for decision support involved having members of the partnership, along with other stakeholder agencies, such as the Environmental Protection Agency, Massachusetts Audubon Society, Urban Harbors Institute, and World Wildlife Federation, define goals for the area. This method prioritized the ecological goals according to stakeholder input and scientific opinion and enables policy makers and stakeholders to view the system in its entirety.

The analysis captured one issue—that of boat activity as a stressor—in the whole island system, then it was quantified scientifically and applied spatially, and interrelationships were examined. The evidence demonstrated that potential disturbance exists. Therefore, to put a priority on what needs protection, this type of scientific evidence must inform policy decisions.

The GIS model also identified the spatial patterns of ecological vulnerability to boat traffic in the islands and surrounding waters. The result was an intuitively appealing, comprehensive, and interactive tool that would aid decision makers and managers in choosing boat routes and defining "no-go" areas for boats.

The project shows how GIS can bridge the gap between scientists, policy makers, and a multitude of stakeholders and shape data into a policy-relevant mechanism through which decision makers receive a comprehensive overview of an issue.

The administration of the park is a complicated undertaking. Many of the factors that Congress weighed in creating the park affect other national parks as well. Mixed ownership, public/private partnerships, and diverse sources of funding are often considered in the design of strategies to protect and preserve scarce natural resources. The park collaborative model will represent an increasingly important precedent as it matures and as lessons are learned about the decision-making process and the outcomes of various choices.

About the Author

Jennifer Bender Ferré, Ph.D., is a consultant for the Stellwagen Bank National Marine Sanctuary. Her work has focused on the development of a decision support tool to assess environmental vulnerability combined with a model that facilitates the integration of scientific knowledge with stakeholders' concerns.

More Information

For more information, contact Jennifer Bender Ferré, Ph.D. (tel.: 617-522-1838, e-mail: This article is based on her doctoral dissertation "Integrating Scientific Expertise into Decision Making: Decision Tools for the Boston Harbor Islands National Recreation Area."

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