The potential wetland restoration sites described in this Plan were identified using a methodology that targets historically filled, tidally restricted, or otherwise severely degraded coastal wetlands. This approach was adapted from previous WRP planning efforts and identifies sites using a combination of existing restoration information, GIS analysis, community input, and extensive field work. The Plan focuses on sites that appear to have practical, physical restoration opportunities. The steps involved in site identification, assessment, and prioritization are described below:
Review of Existing Restoration Information
The Draft Plan draws on several previous studies that identify restoration opportunities in the Great Marsh region. The following existing inventories were utilized during Plan development to help identify and assess potential restoration sites.
Great Marsh Tidal Crossing Inventory and Assessment - Parker River Clean Water Association (PRCWA) produced this report identifying tidal crossings within the Great Marsh coastal region from Cape Ann to New Hampshire and assessed the impact of crossings on tidal flows. The document, produced in 1996, provides one-page summaries for 125 crossings. A 1997 addendum identifies an additional 22 crossings in the study area. Several sites in the inventory have been restored and others are currently being studied for project feasibility. Partial funding was provided by the Massachusetts Office of Coastal Zone Management and the Massachusetts Bays Program.
City of Gloucester Comprehensive River and Stream Habitat Restoration Report - Staff from the Massachusetts Audubon Society North Shore region worked with Gloucester officials and resident volunteers to identify, assess, and prioritize 225 degraded aquatic resources within the city limits. Potential restoration actions include fill removal, dam removal, buffer enhancement, stream daylighting, invasive species control, and stormwater treatment. The report, completed in 2002, provides detailed maps, sketches, photos, and descriptions of all identified restoration opportunities. Partial funding was provided by the Massachusetts Riverways Program.
North Shore Atlas of Tidally Restricted Marshes - Completed in 1996, this study was WRP's first restoration planning project and covers the North Shore coastal region from New Hampshire to Boston . The atlas contains maps of tidal wetland habitats with various classifications and shows locations of 190 potential tidal restrictions and tidally-restricted coastal wetlands. Partial funding was provided by the Massachusetts Bays Program.
Parker River/Essex Bay ACEC Project Tidal Crossings Inventory Datalayer - This datalayer is outdated and will be replaced by the publication of this Restoration Plan. Massachusetts Coastal Zone Management staff compiled a GIS point layer of a tidal crossing inventory and assessment for the Parker River/Essex Bay ACEC project. The focus area for this project includes the areas between Salisbury and Salem . The data is stored as a single MassGIS datalayer. The digital data were compiled in ArcView by on-screen digitizing of points identified in the original PRCWA Great Marsh Tidal Crossing Inventory and Assessment, as well as through outreach efforts to capture local knowledge of sites.
Aerial imagery and other maps and data sources were analyzed through a GIS, computer-based review of the study area to identify sites with characteristics that suggest they are historically filled, tidally restricted, or otherwise significantly degraded wetlands ("suspect sites"). The following digital information sources were used in the GIS analysis:
- MassGIS 1:5,000 scale wetlands and streams layers developed by the Mass DEP Wetlands Conservancy Program through photointerpretation of recent color aerial photography;
- MassGIS 1:5,000 scale 0.5 meter resolution digital true color aerial orthophoto images obtained in 2001 and 2005;
- MassGIS 1:25,000 scale digital images of mid-1980's USGS topographic maps;
- Historic wetlands layer developed by WRP for the study area by digitizing and georeferencing the wetlands delineated on mid-1940s USGS topographic maps (obtained over the internet at no charge from Maptech);
- Digitized and georeferenced historic coastal survey maps and navigation charts developed by various sources that accurately delineate coastal features, including shorelines and salt marshes from the mid-1800s to the early 1900s (see NOAA Office of Coastal Survey for more information.
- Digitized and georeferenced historic aerial photos from the 1950s obtained from various sources.
These digital GIS layers were assembled into a single project file and analyzed simultaneously as overlapping layers using ArcGIS 9.x software. The study area was systematically inspected "frame-by-frame" for suspect sites at a scale of 1:6,000. Potential restriction sites were identified at locations where man-made infrastructure and landscape alterations were observed as potentially restricting or blocking tidal flow to wetlands that historically were influenced by the tides. Other possible alterations were identified where historic data sources showed wetlands that do not appear in contemporary data sources or where aerial imagery revealed un-natural landscape features that suggested wetland alterations. This analysis, combined with information from existing inventories, identified over 250 suspect sites.
After locating each suspect site, a second shapefile was created to delineate all wetland areas potentially affected by the suspected wetland sites. Criteria used to define the extent of affected wetlands included topography, MassGIS Wetlands Conservancy Program Wetlands and Streams, field work (as described below), and delineations of historic salt marsh extent from historic maps and aerial photos.
Field work for initial site reconnaissance was completed in the fall of 2004 to verify GIS information and develop preliminary assessments. The GIS information was loaded onto a laptop computer and brought into the field to assist with the location, inspection, and documentation of the suspect sites. A database was developed and linked to the GIS layers to record a standard set of site attributes and general notes regarding restoration potential. WRP staff were able to access and inspect 75 of the suspect sites, while the remaining sites were not visited, mainly due to private ownership access issues. The lack of site access however did not bar suspect sites from inclusion as potential restoration sites if GIS or other information suggested that they likely present good potential restoration opportunities.
Suspect sites were inspected in the field for practical, physical restoration potential. WRP staff recorded basic site characteristics including wetland type, evidence of alteration, estimated degree of impact on the wetland, potential restoration options, and other factors that could affect the feasibility of a restoration project. Based on the site inspections and/or GIS information, staff used best professional judgment to determine whether a suspect site should be included as a potential restoration site. Of the 279 suspect sites, 108 were determined to likely have some level of restoration potential and are included in this Plan.
After initial site reconnaissance was completed, WRP staff met with municipal officials and residents throughout the study area, as well as other regional and governmental restoration partners, to review and receive input on identified potential restoration sites. This input was incorporated into the site database, and several new sites were subsequently investigated and added to the inventory. WRP will continue to seek and incorporate input on restoration sites during Draft Plan review and in the years ahead as new information becomes available.
Rapid Technical Site Assessments
WRP selected a subset of 24 sites for Rapid Technical Site Assessments (RTSAs) based on preliminary evaluation of restoration potential and baseline data needs, and in consultation with restoration partners. The purpose of the Assessments was to collect more detailed, technical information to support the evaluation of restoration potential and to promote project development. The Assessments were completed by the Louis Berger Group, Inc. (Berger) under a contract with the WRP.
The Assessment protocol is generally based on the Salt Marsh Site Selection Tool Manual developed in Rhode Island (NOAA Coastal Services Center, 2003) and supplemented with additional components from a number of other published assessment techniques including the Wetland Health Assessment Toolbox (Carlisle et al., 1998), Hydrogeomorphic Assessments to Tidal Fridge Wetlands (Shafer and Yozzo, 1998 and Louis Berger Group, 2004), Global Programme of Action Coalition (GPAC) protocols (Neckles and Dionne, 2000), and the Method for the Evaluation and Inventory of Vegetated Tidal Marshes in New Hampshire (Cook et al., 1993), as well as previous tidal restoration planning projects managed by the WRP (e.g., Mount Hope Bay Tidal Restriction Atlas published in 2003). The criterion and qualifiers were refined with input from WRP staff.
The intent of the protocol is to provide standard criteria and a straight forward method for assessing restoration opportunities and identifying restoration priorities. The specific data collection methods used to assess each criterion are described in the RTSA Report. See the Report for a complete description of methodologies utilized and results generated. Site specific RTSA Reports are available and accessed via the Site Table or Interactive Map. See Navigation Help for more information.
Site Evaluation and Prioritization
The 108 potential restoration sites were further evaluated using GIS data, field observations, results of the Rapid Technical Site Assessments, and input from outreach efforts. All sites were given a priority ranking of low, medium, or high. Priority rankings are subjective determinations made using the best professional judgment of WRP staff, while asking this fundamental question: considering all known physical and practical factors, which sites appear to have the greatest restoration potential? The primary criteria for this determination are size, ownership, severity and extent of ecological degradation, potential environmental benefits, and general "do-ability" (which for many sites includes known practical circumstances that may affect a restoration effort). In general, the factors considered in the priority rankings are summarized in the text of the narrative site descriptions. The rankings are not definitive; rather, they are intended as a guide to help communities prioritize potential projects and to aid restoration partners in focusing project development efforts. (See the Site Table listing potential sites by priority ranking.)
It is important to note that regardless of priority ranking, sites are included in this Plan because they likely have some level of restoration potential. The Great Marsh communities and others interested in wetlands restoration are encouraged to assess all sites of interest based on their own criteria that may include local habitat priorities, geographic location, and types of impacts and potential benefits. WRP will update site-specific priority rankings as new information becomes available.