site (TROD and the lowest site (TR06) bracket a 120-mile section 

 of the Tongue River that extends from just below Squirrel Creek 

 near Decker, Montana, to the mouth of the Toncpje River at Miles 

 City. Site TROl is above Tongue River Reservoir; sites TR02 

 through TR06 are below Tongue River Reservoir. 



Elevations at the sampling sites range from about 3,600 feet 

 at the upper site near Decker to about 2,500 feet at the mouth of 

 the Tongue River at Miles City. In the Montana Surface Water 

 Quality Standards, the Tongue River is classified B-2 from the 

 Wyoming boundary to Prairie Dog Coulee (includes sites TROl and 

 TR02) , and B-3 from Prairie Dog Coulee to the Yellowstone River 

 (sites TR03 through TR06) . 



METHODS 



Periphyton samples were collected by Patrick Newby of the 

 MDEQ Monitoring and Data Management Bureau following standard 

 operating procedures of the MDEQ Planning, Prevention, and 

 Assistance Division. Using appropriate tools, microalgae were 

 scraped, brushed, or sucked from natural substrates in proportion 

 to the rank of those substrates at the study site. Macroalgae 

 were picked by hand in proportion to their abundance at the site. 

 All collections of microalgae and macroalgae were pooled into a 

 common container and preserved with Lugol ' s (IKI) solution. 



Samples were examined to estimate the relative abundance and 

 rank by biovolume of diatoms and genera of soft (non-diatom) 

 algae according to the method described in Bahls (1993) . Soft 

 algae were identified using Dillard (1999) , Prescott (1978) , 

 Smith (1950), and Whitford and Schumacher (1984). These books 

 also served as references on the ecology of the soft algae, along 

 with Palmer (1977) . 



