Warhorse Lake contained the second-highest nitrate concentration 

 in the sample set, and the highest among sites of the unglaciated 

 plains. The WET74 sample also contained significant ammonium. The 

 orthophosphorous concentration was one of the lowest of the 

 unglaciated plains, exceeding only non-lacustrine sites (Burns 

 Creek and the Lavina DOT site.) The total phosphorous and total 

 organic carbon concentrations also were relatively low in 

 comparison to other sites in this classification. (The total 

 phosphorous analysis was conducted on a different sample collected 

 under different hydrologic conditions.) 



Arsenic and boron concentrations were relatively low in comparison 

 to other sites in this class. The chromium concentration reported 

 ranks mid-range among the generally enriched nonglaciated plains 

 sites, but still exceeds all sample sites in other ecoregions. The 

 copper concentration reported is the highest in the sample set, 

 exceeding western sites with impacts from mining and mineral 

 processing. 



Chemical history. No other data on the water chemistry of this 

 site are known. The U.S. Fish and Wildlife Service reports no 

 water quality problems or history of visible salinization during 

 low-water conditions. 



Sediments. The extractable iron concentration of the WET74 

 sediment sample was one of the highest in the data set, exceeded 

 only by samples from sites with known impacts from mining and 

 mineral processing. Extractable arsenic, copper, nickel and zinc 

 concentrations were at or near the upper end of the ranges shown 

 for sites in the unglaciated plains. Chromium and vanadium 

 concentrations ranked mid-range or lower within the site class. 

 WET74 was one of the few plains sites without a reportable 

 concentration of extractable boron in the sediment sample. 



Extractable arsenic, copper, nickel and zinc concentrations exceed 

 the geometric mean values for soils of the western United States 

 by factors of 1.5, 2.1, 2.3 and 1.9 respectively. 



