oversaturation with carbonate phases and approximate equilibrium 

 with mirabilite (Na2SO4*10H2O) . Ammonium, total organic carbon and 

 phosphorous concentrations were relatively high. 



Most trace element concentrations analyzed were below reporting 

 limits. Arsenic and boron concentrations, however, were at or near 

 the maximum levels found in the sample set. The chromium 

 concentration was one of the two highest reported for sites outside 

 of the southern Montana (unglaciated) plains. 



CheBical history. Previous sampling shows North Goose Lake to be 

 subject to large temporal variations in salinity. The available 

 data suggest the lake is fairly well mixed internally at any given 

 time, however. Field measurements of specific conductance in 

 September 1984 showed an 18% increase from the southern to northern 

 ends of the lake. Similar measurements in August 1990 showed 

 essentially no difference in specific conductance or pH between the 

 northern and southern ends of the lake. 



Between 1984 and 1990, the specific conductance of North Goose Lake 

 increase by a factor of approximately 2.4; between 1990 and the 

 DHES sampling in 1993, specific conductance increased again by a 

 factor of 1.4. North Goose Lake probably has a Holocene history 

 of complete desiccation during some periods of extreme drought. 



The proportionately high chloride concentration (21% of anions as 

 meq/1) and a known history of poor oilfield brine disposal 

 practices in the area raise the possibility that North Goose Lake 

 is subject to some impacts from contaminated ground water. Most 

 of the lake's solute load is interpreted to be of natural origin, 

 however . 



Sediments. Relatively high concentrations of calcium and magnesium 

 probably reflect the formation of authigenic carbonate minerals in 

 the North Goose Lake basin. Most trace elements analyzed were 

 below reporting limits in the North Goose Lake sediment sample. 

 Extractable boron was near the upper end of the range shown for 

 sites in the glaciated plains; the extractable arsenic, iron and 

 manganese concentrations were toward the lower end of their 

 respective ranges for this site class. 



