DISCHARGE- Ft. per Sec. 
DAYS SINCE RAIN 
Fig. GROUND »,»WATER DEPLETION, CURVES 
May to “Oc. “inel. 
STREAM TEMPERATURE 
Fresh water temperature plays an important role in the physiology of 
aquatic organisms: it affects the metabolism rate; it alters various 
physical, chemical and biotic factors in the waters of the stream. 
Temperature may influence the spawning impulse of salmon; it 
influences egg incubation, and fry development up to the point of 
emergence from the gravel. Pritchard (15) has found that high 
temperatures appear to shorten, and low temperatures to lengthen, 
the incubation period of pink salmon eggs. Donaldson and Foster (6) 
show the optimum temperature range for sockeye salmon fry to be 53° 
to 62° F. Studies by Hanavan and Skud (9) indicate that abnormally 
cold fresh-water stream temperatures, which result in a low salmon fry 
survival rate, may be modified by warmer tidewater to create con- 
ditions more favorable for survival in the inter-tidal zone. Water 
temperature may play an important role in stimulating the migratory 
movement of salmon. Davidson, et al (4), however, found no relation- 
ship between variations in stream temperature and the upstream move- 
ment of salmon. Experience in warmer climates has shown that streams 
may attain temperatures which are critical for certain fish species. 
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