tists commenting on the 1991 proposed revisions indicated that 30% of the bottomland hardwood wetlands in Louisiana would cease to be delineated as wetlands if the 1991 proposed revisions were adopted. This estimate was based on field testing by USACE (Lower Mississippi Valley Division) and the Coalition to Restore Coastal Louisiana. Significant interannual variations in flooding and saturation were cited as reasons that much of the bottomland hardwood forest would fall to meet the hydrologic requirements (personal Communication, Dec. 13, 1991 to Gregory Peck, EPA, from James G. Gosselink and G. Paul Kemp, Coalition to Restore Coastal Louisiana). A study by the Environmental Defense Fund and the World Wildlife Fund suggests that the hydrologic requirements of the 1991 proposed revisions would result in exclusion of approximately 50% of the remaining wetlands in the United States. Substantial areas of bottomland hardwood forest, northeastern and midwestern bog areas, 23% of the Everglades National Park, and 80% of the Great Dismal Swamp in Virginia and North Carolina would be dropped.

As a general matter, it seems certain that less area would be delineated as wetland under the 1991 proposed revisions than under the 1989 or 1987 manuals. The difference results primarily from the proposed requirement that hydrology, soils, and vegetation be documented separately, and from the limitations on indicators that can be used for each, especially hydrology. The 1987 and the 1989 manuals are the most similar of the group. Where there is a difference between the two, it generally results in less area delineated as wetland under the 1987 Corps manual than under the 1989 interagency manual. This is explained mainly by a broader and more flexible array of indicators in the 1989 interagency manual.