McDonald Swamp are natural fens that are fed by groundwater flows 

 from the Teton River. McDonald Creek enters the Teton River 

 below the confluence of the Teton's North and South Forks and 

 above the Teton River sampling site at Breen's (Table 1) . 



McDonald Creek begins and ends in the Montana Valley and 

 Foothill Prairie Ecoregion (Omernik and Gallant 1987) . McDonald 

 Creek is classified B-l in the Montana Surface Water Quality 

 Standards. The most significant source of stress to McDonald 

 Creek is dewatering for irrigation (MDEQ 1998; Carol Endicott, 

 MDEQ, pers . comm. ) . Two sampling sites were located on McDonald 

 Creek, one (upper) just below McDonald Swamp and another (lower) 

 near the mouth of McDonald Creek below the zone of dewatering 

 (Table 1) . 



The Teton River begins in the Northern Rockies Ecoregion, 

 flows across the Montana Valley and Foothill Prairies Ecoregion, 

 and ends in the Northern Great Plains Ecoregion (Omernik and 

 Gallant 1987) . The Teton River is classified B-l above Deep 

 Creek near Choteau, B-2 between Deep Creek and Interstate 15, and 

 B-3 from 1-15 to the mouth. The Teton River is stressed by 

 dewatering for agricultural irrigation, salinization (mostly 

 discharges from Freezeout Lake and Priest Butte Lakes) , channel 

 instability, habitat alteration, and sedimentation (MDEQ 1998; 

 Carol Endicott, MDEQ, pers. comm.). 



The nine sites on the Teton River extend from the North Fork 

 just above its confluence with the South Fork, to the mouth of 

 the Teton River near Loma, Montana (Table 1) . The site on the 

 North Fork has excellent stream and riparian conditions and may 

 be considered as a reference (MDEQ field notes) . The site behind 

 Elizabeth Breen's house is just south of Eureka Reservoir and 

 about 4 miles above Highway 89. This site was established mainly 

 to assess the effects of dewatering for irrigation. 



