RESTORABLE DEPRESSIONAL WETLAND INVENTORY - METADATA

Contact Information

Rex Johnson
United States Fish and Wildlife Service
21932 State Highway 210
Fergus Falls, MN 56537
(218) 736-0606
rex_johnson@fws.gov

Spatial Reference

Projection: UTM Zone 15
Horizontal Datum: NAD 27
Units: Meters

Photointerpretation

National Aerial Photography Program (NAPP) (1:40,000 scale) color infrared (CIR) photographs acquired in April and May, 1991 and 1992, were viewed in stereo pairs at 5X magnification using a Cartographic Engineering stereoscope. A Mylar overlay was mounted on one photo of each stereo pair and a rectangular work area was delineated on the overlay comprising one-quarter of a USGS 7.5 min topographic quadrangle. A minimum of 4 fiduciary marks were placed on the overlay to enable geographic rectification of digital data covering the work area. One fiduciary mark was placed at the corner of the US Geological Survey (USGS) 7.5 min quadrangle and others at conspicuous road intersections near the other 3 corners of the work area. Drained depressional wetlands were delineated on the Mylar overlay within the work area using a 6X0 (.13 mm diameter) rapidograph pen and indelible ink. Collateral data was consulted during the delineation process. These data consisted of published county soil surveys and descriptions of hydric soils, USDA Farm Service Agency compliance slides (aerial 35 mm slides) acquired in 1993 (immediately after a period of intense precipitation), USGS 7.5 min topographic maps, and National Wetlands Inventory (NWI) maps. Black and white NAPP photographs (1:40,000 scale) acquired primarily in August and September, 1996, were reviewed and rejected as collateral data because they were acquired under dry conditions.

Other specific photointerpretation protocols were:

1. All drained depressional wetlands, regardless of size, were delineated.

2. NWI-delineated wetlands with a Ad@ (partially drained) modifier in the classification code were not delineated unless the original delineation failed to encompass the complete historic wetland area.

3. NWI-delineated wetlands that did not contain a Ad@ modifier in the classification code were delineated if the original delineation did not include the entire historic wetland area.

4. Wetlands identified on NWI maps which did not exhibit wetland characteristics (i.e. hydrology, hydrophytes, etc) on new (1992) CIR photography were delineated even if no evidence of drainage was apparent.

5. Wetlands not delineated on NWI maps, and in cropland, were delineated.

6. Wetlands not delineated on NWI maps, and in grassland, were not delineated unless evidence of drainage was observed on the aerial photo.

7. Wetlands not delineated on NWI maps, and in trees, were not delineated.


Tolerances:

Scanned line data were converted to a polygon using a 6 m fuzzy tolerance. Open polygons were manually closed and cleaned with a 1.2 m fuzzy tolerance which was used for all subsequent data processing.

Datafile Description and Attribute Definitions

[County_Name]_nwx - National Wetlands Inventory delineations (see www.nwi.fws.gov for NWI delineation standards). Note: Wetland classifications in these data often differ slightly from the original NWI classification. NWI wetland classifications were simplified for these data by removing mixed classes and multiple special modifiers, and by standardizing letter case. In each case of mixed classes and multiple special modifiers, the first class or special modifier was retained.

Attributes

pl_attribute - simplified NWI classification

major - 2-digit watershed code assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999 (file name -- mnwshpy3)

majname - major watershed name assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999

province - 1-digit province number assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999

provname - watershed province name assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999


[County_Name]_rwi - Restorable Wetland Inventory (RWI) delineations

Attributes

Restorable - 0 = Islands and the Universal Polygon
100 = Restorable depressional wetland delineated using protocols described above

major - 2-digit watershed code assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999 (file name -- mnwshpy3)

majname - major watershed name assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999

province - 1-digit province number assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999

provname - watershed province name assigned by MN Department of Natural Resources in their Minnesota Watersheds coverage, circa 1999

Note: A 'd' special modifier in pl_attribute of [County_Name]_nwx indicates a wetland effected by drainage. NWI-delineated wetlands were only re-delineated in the Restorable Wetland Inventory if one of the following conditions applied:

1. The historic basin footprint was significantly larger than the NWI delineation with the 'd' modifier; or
2. The NWI delineation did not include a 'd' modifier and evidence of drainage was visible during the Restorable Wetland Inventory.

To see a comprehensive map of restorable wetlands (drainage-modified and drained-eliminated) it is necessary to display the RWI data and the NWX polygons with 'd' modifiers.