Northern Prairie Wildlife Research Center
Table 2. Comparisons of expected and observed wetland alterations from 70 discharges of fill material authorized under Section 404 of the Clean Water Act by nationwide permits (NWP) 13, 14, and 26 and by individual permits; prairie pothole region of North Dakota, 1987 - 1991. Expected alterations are based on figures in permit applications submitted to the U.S. Army Corps of Engineers. Mean-percent difference is the average difference between the expected and observed alterations. The parenthetical entries in the table field are the English units of measure that are used in the regulatory program of the U.S. Army Corps of Engineers.
| Alterations | NWP 13 | NWP 14 | NWP 26 (<1 acre) [sic] | NWP 26 (1-10 acres) [sic] | Individual permits | ||
| Volume | Area | Volume | Area | ||||
| n | 15 | 19 | 8 | 9 | 3 | 15 | 1 |
| Expected | 1,192 m | 2,057 m3 | 5,331 m3 | 1.6 ha | 7.0 ha | 110,188 m3 | 4.0 ha |
| (3,910 feet) | (2,691 yd3) | (6,972 yd3) | (4.0 a) | (17.3 a) | (144,112 yd3) | (9.8 a) | |
| Observed | 1,191 m | 2,062 m3 | 5,249 m3 | 1.9 ha | 6.8 ha | 104,196 m3 | 4.0 ha |
| (3,905 feet) | (2,697 yd3) | (6,865 yd3) | (4.7 a) | (16.8 a) | (136,275 yd3) | (9.8 a) | |
| Mean % difference | 4% | 4% | 147% | 5% | 9% | ||
U.S. Department of the Interior |
U.S. Geological Survey
URL: http://www.npwrc.usgs.gov/resource/wetlands/wetlperm/table2.htm
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