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New Jersey Maps its Wetlands

To more efficiently regulate the preservation of its wetlands, New Jersey has developed a GIS basemap accurate to within an acre.

Aug 95

Level of Govt: State

Function: GIS

Problem/situation: To preserve wetlands, regulatory agencies need to ascertain the location and extent of the protected areas.

Solution: GIS database accurate to within an acre.

Jurisdiction: New Jersey

Vendors: ESRI, Markhurd, Greenhorne & O'Mara.

By Bill McGarigle

Special to Government Technology

Few areas in the nation have lost more wetlands than the state of New Jersey. The major causes are a growing population, expanding development and, until recently, a lack of effective resource management tools.

The problem is compounded by New Jersey's geography. According to the state's Land Use Regulation Program administrator, Ernest Hahn, "If you get any size parcel in New Jersey, you'll probably have some wetlands associated with them - there are no vast areas of the state that do not have wetlands resources, even in the hilly country of North Jersey."

The state's first attempt to stem the loss of coastal wetlands was the Wetlands Act of 1970. "They passed that act," explained Hahn, "because we were having wholesale destruction of those areas as a result of houses built out on the marshes. [Developers] would just fill in the marsh and push out a new road. Everybody would get a lagoon and a waterfront lot." The Wetlands Act of 1970 required the state to completely map all coastal wetlands and create maps that could be used as a regulatory tool in screening applications.

However, wetlands and their associated wildlife habitats continued to disappear. Checking the decline required more personnel and state-of-the-art, resource-management tools than budget-strapped states and the federal government could provide. Despite the National Clean Water Act, cutbacks in the federal budget had left the Army Corps of Engineers (ACOE), Environmental Protection Agency (EPA) and National Fish and Wildlife (NF&WL;) Service with insufficient resources to adequately protect and enforce regulation of New Jersey's freshwater wetlands. In 1987, the only graphic resources available were the National Fish and Wildlife Service inventory (NWI) maps, at a scale of 1:24,000 - excellent for some applications, but not a large enough scale for regulatory purposes. For zoning, management and the protection of wildlife habitats, planning boards need maps with linear features down to an acre.


In 1986, the accelerating loss of wetlands prompted then-Gov. Thomas Kean to put a moratorium on building in the state's wetlands until the Legislature came up with a bill that gave New Jersey the resources and authority needed to regulate and protect its own wetlands resources. New Jersey lawmakers responded with the Freshwater Wetlands Protection Act (FWWPA) of 1987.

Under the Clean Water Act, the federal government has the authority to regulate and permit wetlands throughout the nation. However, Section 404 of the act grants states with sufficient resources the right to assume these responsibilities. In view of the limited resources of the ACOE, EPA and USF&WL; services, New Jersey lawmakers felt the state could do a better job regulating and monitoring their own wetlands. By the mid-1980s, the New Jersey Department of Environmental Protection (NJDEP) had an ArcInfo Geographic Information System (GIS) from Redlands, Calif.-based Environmental Systems Research Institute (ESRI) in place, and strict regulations protecting and permitting wetlands. The state then assumed self-regulation of its wetlands under a mandate from the FWWPA, referred to as "Assumption 404."

Another mandate under the FWWPA charged NJDEP with developing a comprehensive inventory of the state's freshwater wetlands. The purpose: to provide agencies with a statewide planning tool for early detection and assessment of changes in wetlands. The project called for mapping and classifying over 620,00 acres in the state.

Begun in 1988 as a three-year project, state administrators and contractors struggled through delays caused by budget cutbacks, years of unstable funding and unusually heavy snowfall that delayed the color infrared aerial photography. The project was finally completed last spring at a cost of $3.7 million.


The prime contractor for the freshwater wetlands mapping project was Markhurd of Minneapolis. The company was responsible for developing digital ortho quarter-quad (DOQQ)2 basemaps and delineation overlays in ArcInfo format, and conventional photo basemaps on Mylar with superimposed wetlands delineations. To date, New Jersey is only one of two states to have complete DOQQ coverage of the entire state.

The subcontractor, Greenhorne & O'Mara, of Greenbelt, Md., provided photo analysis and interpretation, field verification, and a signature key to identify and classify ground features.

The 1:58,000-scale aerial photography, taken by the National Aerial Photographic Program was shot in March and April of 1986 and 1992, during the wettest ground conditions and before the spring leaf out. Color infrared (CIR) imagery was chosen specifically for its ability to discriminate vegetation types and various levels of soil saturation.

The aerial photos provided the images from which DOQQ basemaps were developed. Each quarter quad covers an area of roughly 12.5 square miles and has a minimum mapping unit of one acre, enabling analysts to delineate all wetland features down to 10 feet in width.

NJDEP's contract manager for the project, Bob Cubberly, said that since the quarter-quad basemaps were digitized for GIS applications, they had to fit together like puzzle pieces. "We had to have a cartographic base that produced a seamless edge match. That's where the prime contractor, Markhurd, came in. They considered the whole state in the solution, instead of in blocks or strips, so all the map edges match; the corner coordinates of all the quarter quads are shared between adjacent maps." A total of 624 quarter quads were required to cover the entire state.

Following extensive quality-control processes, digitized composites of the basemaps with wetland delineations were delivered to the NJDEP in ArcInfo format, along with a database of all field information, including post-processed GPS data recorded by field verification teams. Other deliverables included hard copies of basemaps, Mylar composites of the basemaps and delineations, and acetate copies of only wetlands delineations.


The wetlands GIS maps and database are proving effective and versatile resource-management tools for the NJDEP, enabling state officials and scientists to make informed decisions about present applications, and to rapidly assess the impact of developments on wetland resources. Wildlife biologists are also using the maps to identify and monitor locations of threatened and endangered species habitats and to protect rare plant communities.

Under data-sharing agreements, most counties in New Jersey with GIS now have overlays of the wetlands delineations. The databases are also being used in emergency preparedness; officials can model the probable extent of an oil spill in a waterway, identify areas that will be affected, and determine appropriate responses. As for the overall cost of the mapping project, some of that will be recovered through map sales to developers, local Realtors and property owners.


Ernest Hahn stresses that the GIS is not a regulatory tool. "There are some people who would like to see us going into a GIS terminal, bringing up a map and regulate from the computer. While the GIS has valuable applications in resource management, the bottom line is that most of the calls we make just can't be made off the computer screen. You're looking at things like endangered and threatened species habitats, whether or not they are connected to surface-water features," he said. "Those are really the things that need to be looked at in the field." The reason, he said, is that connections between habitats are analyzed. "You can only get to a certain level of detail with remote sensing," he said.

Comparing the present program with previous federal and state efforts, Hahn said "we have a much more comprehensive program. We've thrown a lot more people at it than the Army Corps of Engineers did. They didn't have the resources to adequately enforce the program. We believe that we do.

"As a result, other [state] resource agencies will get a better handle on what's going on because we do a more thorough investigation of all the permits that come in front of us," Hahn said. "So the advantage is twofold: one, it streamlines the process, and two, we're more effective in protecting the resources of the state."

Bill McGarigle is a freelance writer residing in Santa Cruz, Calif.