13 



(1976). 



Annual stream flow variation was determined by the use of past discharge 

 records and estimates from governmental agencies . Late summer streamf low 

 discharge for each stream was measured with a gurley "pigmy" flow meter. 

 Stream discharge gauging records were available only for Bozeman Creek. The 

 USDA Soil Conservation Service operated a gauge at stream kilometer 5.6 in 1977 

 and 1978. 

 Data Analysis 



The mean values of urban- and control-section data on habitat and trout 

 population variables were compared. The data were examined for significant 

 differences via the non-parametric Mann-Whitney U test. 



Data on habitat variables were entered into the Wyoming Habitat Quality 

 Index Model II (Binns 1979). The resultant predictions of trout abundance in 

 kilograms per hectare were compared with the actual measurements of trout 

 abundance. 



The relationship of trout abundance to habitat variables was further 

 analysed by multiple-regression modelling. The logarithms (base 10) of habitat 

 data were entered as independent variables. The logarithms of four expressions 

 of trout abundance (number of over-20-cm trout per stream kilometer and per 

 hectare and kilograms of all trout per stream kilometer and per hectare) were 

 entered separately as dependent variables. In the step-wise procedure, the 

 F- value set for exclusion of independent variables from the model was 1.0. 



RESULTS AND DISCUSSION 



Comparisons between Urban and Control Areas 



The most striking difference detected between urban and control areas of 



