dissolved aluminum concentration in a June 17 sample was 0.11 milli- 

 gram per litre, which was 0.01 milligram per litre above the recom- 

 mended value. Investigations of U.S. Geological Survey and Environ- 

 ment Canada quality assurance data have identified potential i icom- 

 patibility with parameters (boron, lead, zinc, and iron). 



The outer limit of the cone of depression from coal seam dewataring 

 moved closer to the International Boundary. Several new observation 

 wells were established by the Montana Bureau of Mines and Geology 

 south of the border with the assistance of the Saskatchewan Power 

 Corporation. 



The total estimated seepage from the ash lagoons and polishing ponds 

 was 0.556 litre per second, well below the seepage limits proposed by 

 the International Poplar River Water Quality Board. The leachate 

 front has been calculated to have advanced 2.5 metres towards Cookson 

 Reservoir since the ponds were first filled. 



Plant stack emissions did not cause or contribute to violation of 

 Montana, United States, or Saskatchewan ambient air quality stan- 

 dards. 



During the year the Saskatchewan Power Corporation sold the coal 

 mine to private interests. The private interests hold coal proper- 

 ties elsewhere in the area and propose to close the existing mine in 

 about 5 years. 



