In search of the wetland boundary
Implementation of Section 404 of the Federal Water Pollution Control Act of 1972 and the “swampbuster” provisions of the Food Security Act of 1985 require identification and delineation of wetlands in accordance with applicable statutes and regulations. While a considerable amount of work has gone into characterizing wetlands, very little has gone toward delineating the boundary between unregulated uplands and regulated wetlands. We attempted to delineate this boundary in a tidal saltmarsh and a wooded swamp and along an intermittent stream in North Carolina. Comparisons were based on contour maps of wetland index values. The locations of boundaries derived from Corps of Engineers and Soil Conservation Service indices differed little. However, inclusion of “facultative” species within the aggregate of wetland plants produced a much larger area of “wetland” than hydrographic or soils indicators. Elimination of facultative species brought the three indicators into much closer agreement. The procedures described are appropriate for calibrating and verifying boundaries determined by professional judgment and in situations where the high cost is otherwise warranted, but are not suitable for routine boundary determinations.