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 Montana 



The State of Montana operated one primary air monitoring site and 

 eight additional sulfation rate sites in the Poplar River area of 

 Montana during 1986. The parameters monitored included: sulphur 

 dioxide, total suspended particulate, sulfation rate, wind speed, wind 

 direction, and temperature. The primary air monitoring site was estab- 

 lished in September 1986 and is expected to continue through June 

 1987. The 1985 Montana Legislature provided funding for one site for 

 1 year. The site is located at the Don Marlenee Ranch, which is 

 approximately 4 miles south of the border and 1 mile east of Highway 

 13. No continuous monitoring was conducted between July 1985 and 

 August 1986, but sulfation rate analyses at selected sites were con- 

 ducted during the interim. The monitoring results are summarized in 

 table 9. 



During the last half of 1986, sulphur dioxide concentrations remained 

 less than both Montana and United States ambient air quality standards. 

 The maximum 1-hour concentration of 7.5 pphm was recorded at the 

 Marlenee Ranch site during October. This concentration is 15 percent 

 of the Montana standard. The highest 24-hour concentration of 0.6 

 pphm occurred during November. Most of the higher sulphur dioxide 

 concentrations occurred with northwest winds, indicating that the 

 Saskatchewan Power Corporation generating facilities were the source. 



The Montana and United States standards for total suspended particulates 

 were not exceeded at the monitoring site. The highest 24-hour concen- 

 tration was 140 Ug/m^, recorded on November 10, 1987. The annual 

 geometric and arithmetic means for the 4 months the site ran in 1986 

 were 18.7 Mg/m^ and 28.9 Pg/m^, respectively. The levels of total sus- 

 pended particulates observed during 1986 are low and representative of 

 rural Montana. 



