values shown by sites classified with Lake Bowdoin. Phosphorous 

 (total and orthophosphorous concentrations) and total organic 

 concentrations were noticeably higher than at the WET36 site at the 

 lake inlet. The arsenic concentration ranked toward the lower end 

 of the range shown by Great Plains sites; boron, copper and iron 

 concentrations ranked mid-range within the site classification, all 

 somewhat higher than at WET36. Other trace element concentrations 

 were below reporting limits. 



Chemical history. Since 1978, the U.S. Fish and Wildlife Service 

 has conducted periodic monitoring of limited water quality 

 parameters at a site on the eastern arm of Lake Bowdoin, less than 

 a mile from WET38. As with the inlet-area station, these data show 

 a wide range in specific conductance, pH and dissolved oxygen. 

 Reported values of specific conductance range from less than 1000 

 microsiemens/cm to 39000 microsiemens/cm, and reported pH values 

 range from 8.1 to an extremely high 11.0 . The specific 

 conductance measured for this sample (7800 microsiemens/cm) was 

 considerably below the simple average for the USFWS data for this 

 site (10871 microsiemens/cm for 151 measurements). 



As at WET36, reported dissolved oxygen measurements also show a 

 rather wide range, including summertime lows in the 1 to 2 mg/1 

 range. No wintertime data have been collected as part of this 

 monitoring program. 



While there is some question about the extreme pH values reported, 

 generally these data show a very wide seasonal and interannual 

 variability at this site, driven by periodic importation of dilute 

 water from the Dodson Canal, followed by periods of evaporative 

 concentration in an essentially closed-basin setting. 



The spatial variability shown by the DHES sampling is significant; 

 near-synoptic sampling of this site and WET36 near the lake inlet 

 showed a 30% increase in total dissolved solids from inlet to 

 outlet areas. The mean specific conductance values for U.S. Fish 

 and Wildlife Service measurements from correlative sites show a 43% 

 higher mean for the outlet end of the lake. Generally, the 

 salinity gradient is likely to be steeper during more strongly 

 evaporative conditions. Nitrogen (nitrate and ammonium) 

 concentrations were indistinguishable between WET38 and WET36. 

 Total and orthophosphorous concentrations, however, increased 

 disproportionately with respect to salinity from inlet to outlet 

 areas (80% and 74% respectively). 



Sediments. The wide range of reported concentration of solutes in 

 the water column implies that periodic dissolution and re- 

 precipitation of authigenic mineral phases may occur at this site, 

 perhaps with complex effects on aqueous concentrations of nutrients 

 and trace elements. The sediment sample collected from this site 

 showed generally enriched trace element concentrations in 

 comparison to the other Bowdoin sites. This may reflect 

 heterogeneities in sediment grain size and other characteristics; 

 alternatively, irrigation return flows delivered to the 



