Surface water inlet and outlet f Fields surf in a nd surf outK 



Surface water inlet and outlet codes reflect the appearance 

 of these features on the most current 7.5 minute USGS topographic 

 quadrangle maps. In a few cases (the Blackfoot WPA for instance) 

 field observations of inlet or outlet features disagree with map 

 symbology. In these cases field observations prevail. 



Reservoirs are coded as having surface water outlets even 

 where spillways are known to convey water only periodically. All 

 inlet and outlet streams, including those shown as non-perennial 

 on the topographic quadrangles, are considered. 



HYdroloaic manipulation (Fields impound and iinix)rtl . 



The existence of impoundments (dams or dikes) and water 

 imports are coded on the basis of features shown on the most 

 current 7.5 minute topographic quadrangles, supplemented with 

 information gathered in the field and from land management 

 agencies. The shortcomings of using topographic map data are 

 recognized; nevertheless map data probably identify most of the 

 significant hydrologic modifications of these types. 



There are a handful of known sites (and probably others) where 

 abandoned or breached structures which are no longer functional 

 controlled water inputs and storage at one time, (e.g., Jarina). 

 Where known, these types of wetlands are coded as lacking these 

 structural features. 



Mean Annual Evaporation rate (Field Evapl 



The value entered in the Evap field is the Penman method value 

 (in inches per year) for the MAPS database cell within which the 

 sample site is located. The use of Penman values is not intended 

 to suggest that they necessarily represent the best estimates of 

 evaporative and evapotranspirative water loss from the sampled 

 wetlands. The values are intended as relative indices of the 

 intensity of evaporative forcing. Penman potential evaporation and 

 Thornwaite potential evapotranspiration values are both available 

 statewide through the MAPS atlas; when compared to pan evaporation 

 data for 12 longer-term climatic sites. Penman values appear to be 

 a more sensitive index of measured (pan) rates and are therefore 

 considered a more useful value against which to evaluate wetland 

 characteristics . 



Mean Annual Prec ipitation (Field Mean pre^ 



The values entered in the mean precipitation field are the 

 mean of the range of values (in inches per year) for the MAPS 

 database cell within which the sample site is located. These MAPS 

 values were in turn derived from the 1978 Soil Conservation Service 

 compilation of Montana precipitation for the 30-year period 1941- 

 70 (Caprio et al, 1994). The MAPS site values were compared to the 



