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Summer/Fall 1995 WATER TALK Page 15 <br />...continued from page 14 <br />NWI maps are based upon wetland <br />conditions on the ground during the date of <br />the aerial photography. Mapping for the NWI <br />in Minnesota was based on black/white and <br />color infrared high altitude photography <br />dating from the years 1974 through 1984. <br />The data does not include linear wetlands <br />(wetlands drawn as a line on the NWI maps), <br />nor do they include point wetlands (wetlands <br />drawn as a dot). There is no minimum <br />wetland mapping size on an NWI map. <br />Results <br />The northern forest counties account for the <br />majority of wetland acreage. For example, the <br />three counties of Beltrami, Koochiching, and St. <br />Louis (Figure 1) each have close to a million <br />acres of wetland. Large peatlands occur in <br />these northern <br />counties. which <br />are larger in <br />size compared <br />with. other <br />counties in the <br />rest of the state. <br />Figure 2 is a <br />measure of <br />wetland area as <br />a percentage of <br />the county. <br />Here, the three <br />counties with <br />the highest <br />percentage of <br />wetland. are <br />Lake of the <br />Woods. <br />Beltrami, and <br />Koochiching. <br />'There is a <br />decrease in <br />wetlands <br />acreage both. to <br />the west along <br />the North <br />Dakota border <br />and to the <br />south. All the <br />southern <br />counties have <br />less than 16% <br />of their land <br />area. covered by <br />wetland. <br />~,. - - <br />T ~ ~ <br />~ (~" ~ '~ . ~ ~~.'~. c <br />. ~ PEMFJ ~ ~`'~ ~ ~ <br />~J <br />f~ _ . ° <br />1 -- <br />AC ~ 510~~ PSStOd PEM <br />P55~~~ 55~~ _ ~,. G <br />~~ Penn ~ PEr~ga ~ . <br />~ ~ - - - - - - ~Fi-.d <br />~~ TP55~0d - -tjEtViC=~ <br />-~~_!9Ennc - Q ~ PFm <br />~Qy _ 9--PEMA PEMC`~ <br />~.- PEMC <br />QEMOd „ . /~ oc\A(' <br />This example of a NWI map in Benton Countyshows the variety of <br />types, shapes and sizes of wetlands shown on the maps. <br />Keep in mind that wetlands have changed <br />since the date of the photography. Much <br />wetland destruction has occurred since the <br />1970's and 1980's. Also the U.S. Fish and <br />Wildlife Service and the Minnesota Department <br />of Natural <br />NWI Acres as (%) of County <br />0.16.602 <br />:~;~~,,~ 16.602.33.205 <br />i ~ ' 33.205-49.807 <br />,~~~. <br />49.807-66.41 <br />Resources has <br />been restoring <br />wetlands over <br />the past several <br />years. <br />As a result <br />of a policy <br />decision made <br />early on in the <br />irrventory <br />process, the <br />NWI decided <br />not to map <br />farmed <br />wetlands unless <br />the wetland was <br />a pothole-like <br />depression or a <br />cranberry bog. <br />Wetlands <br />located along <br />major rivers, <br />such as the <br />Minnesota and <br />Mississippi <br />River systems, <br />that are farmed <br />and cultivated, <br />are not on the <br />NWI maps. <br />...continued on page 16 <br />