are disproportionately important to wildlife, sup- 

 porting a great variety of species. The riparian 

 wetlands form an integrated system with adjacent 

 uplands, and are therefore difficult to distinguish; 

 together, the two ecosystems provide food and 

 cover to both resident and migratory species. Crop 

 conversion, overgrazing, dam construction, and 

 groundwater pumping have altered, severely 

 damaged, or destroyed riparian wetlands to the 

 point where they are considered the most modified 

 land type in the West. For example, 44 percent of 

 Cottonwood communities along the Colorado River 

 in Arizona have been lost and 98 percent of the 

 original riparian forest along California's Sacra- 

 mento River is gone. Remaining riparian lands suf- 

 fer from poor water quality and reduced stream- 

 flows {43). 



Western riparian areas are difficult to approximate 

 with MLRA's because they occur along rivers in 

 Arizona, New Mexico, Utah, Nevada, Colorado, 

 California, Oregon, and Washington. Seven MLRA's 

 were used to capture riparian wetlands, with a total 

 of 45 million acres. In 1982, the predominant land 



use was rangeland, with 11 million acres in 

 cropland. Wetlands in the seven areas covered 1.4 

 million acres. Only 2,000 acres had high potential 

 for conversion, and 33,000 had medium potential. 



Other Problem Areas for Conversion 



Since only one-third of wetlands with high 

 cropland conversion potential were captured in the 

 six problem areas, we identified all other MLRA's 

 with substantial wetlands of high and medium 

 potential. Eight such areas are listed in table 15 and 

 shown in figure 6. These areas, concentrated in the 

 Southeast and the Corn Belt, contain an additional 

 20.8 million acres of wetlands, including 45 percent 

 of high conversion potential acres and 29 percent 

 of medium conversion potential acres. Taken 

 together, the first six problem areas and these eight 

 areas include 57 percent of non-Federal wetland 

 acres, and capture 82 percent of all wetlands with 

 high conversion potential. 



Several of the additional eight areas are considered 

 important for waterfowl: Puget Sound, the Hudson 



Table 15 — Conversion potential of other wetland problem areas, 1982 



•Includes wetland with no conversion potential and where conversion potential was not estimated. 



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