22 



CONSKHVATIOX DkI'ARTMEXT 



Table 3.— Probable Kelation of :Maximum Air and Water Temperatures 

 IN North Branch Fish Creek, Lewis Co., Located in a Forested Country, 

 1,600 TO 1,900 Feet Elevation 



Max. air temperature 



Max. water temperature, brook trout 



90 



76 



Certain corrections were made for densely shaded streams and 

 also for the hour a reading was taken. In the former case, the 

 water temperatures are held down on hottest days much more 

 than on days of averao^e temperature. For example, on a daj^ 

 showing: an air temperture of 80° F., the correspondino- water 

 temperature might be two or three degrees higher than given in 

 the tables and yet not exceed the critical point on the hottest days. 



With reference to the hour of recording water temperatures, it 

 may be said in general, that the water temperature lags behind a 

 rising air temperature. Hence in the morning, it may not neces- 

 arily bear the same relation to the air temperature as in the after- 

 noon. Just hoAV much of a correction must be made for this factor, 

 cannot be tabulated at the present time. It is to be hoped that an 

 opi)ortunity may come another year for securing a large series of 

 liourly temperatures from some of the warmer streams in whicli 

 trout are known to thrive. 



During the past summer one occasion presented itself for obtain- 

 ing such data in the Wiscoy creek and two of its tributaries, all 

 of which are noteworthy fishing streams. The records are pre- 

 sented in Table 4, more for the purpose of future comparison than 

 for immediate interpretation. 



Table 4. — Comparison of Air and Water Temperatures in Three Trout 

 Streams, Altitude 1,594 to 1,734 Feet. Maximum Air Temperature for 

 This Region Ranges from about 88° to 92° F. 



Brown Trout and Brook Trout Present 



NORTH branch WIS- 

 COY, AUGUST 3, 1928 



Hour 



10 :45 



11 :00 



12 :00 



1 :00 



2 :()() 



3 :00 



4 :00 



5 :00 

 5 :30 



Air 

 tem- 

 pera- 

 ture 



81.5 



82 



79* 



83 



84 



86 



84.5 



84 



83 



Water 

 tem- 

 pera- 

 ture 



TROUT brook 

 AUGUST 4, 1928 



Hour 



67 



67 



69.5 



72 



72.5 



75 



75.5 



74 



73 



10 :35 



11 :05 



12 :00 



1 :00 



2 -.00 



3 :00 



4 :00 



5 :00 



Air 

 tem- 

 pera- 

 ture 



Water 

 tem- 

 ))cra- 

 tiire 



* Air temperature dropped 3° due to clouds and a 10 minute shower, 

 short to influence water temperature. 



Duration of shower too 



