Colter Campground 



Climatic setting. The net annual precipitation balance estimated 

 from the MAPS database for the Colter Campground is 44 inches. 

 Because both precipitation and evaporation estimates are subject 

 to large uncertainties in this high-relief setting, this value is 

 not thought to have significance beyond indicating the 

 precipitation-surplus character of the site. Mean monthly 

 precipitation for the Cooke City climatic station shows relatively 

 evenly distributed precipitation throughout the year. Annual 

 totals for Cooke City show below-average values throughout the late 

 1980s and early 1990s. The total precipitation in 1993 (the year 

 prior to sampling) was near the average for the period of record. 



Geologic setting. Glacial deposits of unknown but probably coarse- 

 grained character underlie the site and are inferred to impound the 

 wetland basin. Local lithologies which are inferred to have 

 contributed to glacial sediments include Archaean gneiss and 

 (probably) mafic to intermediate volcanic and intrusive rocks and 

 (possibly) Paleozoic sedimentary formations. At the site of the 

 sample wetland, glacial deposits overlie metamorphic rocks of 

 Archaean age. 



Hydrologic type. The Colter Campground wetland is a high-elevation 

 glacial depression lacking mapped surface water inflow or surface 

 water outflow. Because the site is in an area of precipitation 

 surplus yet lacks surface outflow, it is inferred that ground-water 

 outflow is Important to the wetland 's water balance. 



Basin characteristics. The surface catchment to wetland area ratio 

 derived from topographic mapping of this site is relatively high. 

 Map information may underestimate the area of the wetland, however. 

 Inflow to the wetland is inferred to be from runoff and local 

 ground-water flow within the small catchment, driven by relatively 

 high precipitation rates. 



Water chemistry- The Colter Campground wetland contains dilute, 

 near-neutral calcium/bicarbonate water. Mineral equilibria 

 indicate substantial undersaturation with respect to carbonate 

 phases. Nitrate and ammonia concentrations were below detection 

 limits at the time of sampling. Orthophosphorous and total 

 phosphorous concentrations were low in comparison to sample sites 

 of all classes. The total organic carbon concentration reported 

 is mid-range with respect to the range shown by sample sites of 

 this class. 



Among sample sites in the same class, WET13 ranks near the middle 

 in iron concentration. Most trace elements were reported to be 

 below detection limits. 



Chemical history. No other chemical data for this site are known. 

 By inference, water chemistry in this site probably varies over a 

 narrow and dilute range. 



