Primary purpose
To predict the relative ecological significance of wetlands within their watershed and region using a GIS-based landscape-scale procedure. Developed for use in planning and overall management of wetlands rather than for regulatory decisions.
Expertise needed
Professional(s) who have training and experience in wetland science.
Applicable habitat types
Tidal and non-tidal wetlands in the North Carolina coastal area.
Categories assessed
Eleven functions are addressed: surface runoff storage; floodwater storage; shoreline stabilization; terrestrial wildlife; aquatic life; nonpoint source; floodwater cleansing; landscape character; water characteristics; replacement difficulty; and restoration potential.
Procedure
The user accesses the automated version of NC-CREWS to identify and assess a wetland area. Using GIS analysis, a High, Medium, or Low rating is assigned to each of 39 parameters that describe the landscape and internal wetland characteristics. The parameter ratings are successively combined to produce ratings (H, M, or L) for subfunctions and primary functions. The primary function ratings are combined to form an overall rating of the wetlands ecological significance (i.e., beneficial significance, substantial significance, or exceptional significance).
Key Terminology
Overall ecological significance: rating of a wetland determined by the degree to which it performs or has the capacity to perform water quality, hydrologic, and habitat functions, in addition to a risk factor. The three ratings are beneficial significance, substantial significance, and exceptional significance.
Primary function: three broad groupings of wetland functions (i.e., water quality, hydrologic, and habitat) which are a combination of separate more specific subfunctions.
Risk factor: a factor used in determining ecological significance, that considers the potential risk to watershed and landscape integrity if the wetland functions were lost, i.e., a means of considering cumulative impacts and practicality of replacing lost functions.
Subfunction: specific functions that are separately assessed and combined into 1 of 3 primary functions (e.g., non point source and floodwater cleansing are subfunctions of water quality).
Output
Measure of overall ecological significance of a wetland within its watershed and the larger landscape.
Estimated time to assess 1 acre site
Total 24-72 hours per watershed.
24-72 hours: Access automated version of NC-CREWS (step 1), identify wetland area and initiate NC-CREWS program (step 2), and print results (step 3).
Comparison of habitat types
Can directly compare wetlands (from the same or different wetland class) within the North Carolina coastal area.
Contact person
Jim Stanfill, Division of Coastal Management, North Carolina Department of Environment and Natural Resources, P.O. Box 27687, Raleigh, NC 27611 phone: (919) 733-2293; fax: (919) 733-1495; e-mail: jim_stanfill@mail.enr.state.nc.us
Use as guide to design
The NC-CREWS models should not be used as a guide to design, however, individual variables (parameters) may provide useful information. It is not the intended purpose for the procedure, therefore, it contains properties that limit its application for this purpose. For example, NC-CREWS uses opportunity variables, but does not set upper limits on those opportunities that could potentially reduce functional capacity (e.g., a wetland located near a pollutant generating area is assigned a high rating). In some circumstances, a wetland may not have the capacity to remove all nutrient input. An upper limit on the opportunity must be defined to insure that the existing or planned wetland can predictably have the capacity to provide a function. Also, NC-CREWS does not provide validated threshold values for many variables, and does not include elements important to design at the site-specific level because it is a landscape procedure. Some of the variables may provide useful information. Users can refer to the variables to determine which conditions increase or decrease function. This can be translated into explicit design criteria (e.g., design a wetland >100 ft. wide). However, the design criteria may be unsuitable and the overall rating of function may be misleading for reasons given above.
Related procedures
NC-CREWS has been modified to evaluate wetland restoration and enhancement sites (i.e., Restoration Functional Assessment Procedure). NC-CREWS is currently being modified for use in the Piedmont areas of North Carolina.
Extent of use/field testing
NC-CREWS was developed in Carteret County, North Carolina based on field data collected from over 400 sites. It is being applied to all wetland areas located in North Carolina’s 20 coastal counties. There are plans to continue to counties within in the upper Coastal Plain during the next two years. NC-CREWS has been used on a variety of projects (e.g., large highway projects, bridge construction, wetland acquisition priority rankings, wetland restoration priority ranking, and CAMA land use planning).
Proposed future revisions
NC-CREWS will be reviewed annually and updated as necessary. Major revisions will most likely occur on a five year cycle.
Key Reference
Sutter, L.A. and J.R. Wuenscher. 1996. NC-CREWS: A Wetland Functional Assessment Procedure for the North Carolina Coastal Area (Draft). Division of Coastal Management, North Carolina Department of Environment and Natural Resources, Raleigh, NC. 61 pages appen.