ly, winter precipitation is very uniform; the 

 average precipitation varies only one-half inch 

 per month during the December-through- 

 April period. 



Farmer and Fletcher (1971) completed a 

 detailed analysis of all intensity gage records 

 obtained from DCEW through 1968; at some 

 stations, this included up to 30 years of rec- 

 ords. These records gave evidence that most 

 summer storms are of less than 6 hours dura- 

 tion and that intensity generally decreases 

 with elevation. Also, the records revealed that 

 total rainfall at DCEW is generally highest in 

 the upper reaches of Farmington Canyon 

 from about 6,000 to 8,000 feet elevation, 

 which includes our study watersheds, the East 

 Branch and West Branch of Chicken Creek. 

 Figure 4 shows the probable recurrence inter- 

 val for various storm intensities that range 2 



minutes to 6 hours in duration (Farmer and 

 Fletcher 1971). For example, a storm having 

 a maximum 5-minute intensity of 3.7 inches 

 per hour has a probable recurrence interval of 

 10 years; a storm having a maximum 5-minute 

 intensity of 6 inches per hour has a recurrence 

 interval of 50 years. 



During the entire period of record on our 

 study watersheds, the maximum 5-minute in- 

 tensity recorded was 2.04 inches per hour. 



A snow course has been maintained at 

 7,600 feet elevation on the West Branch wa- 

 tershed since 1967. During the period of rec- 

 ord, the average snow depth for April 1 was 

 53.3 inches and the average water content for 

 that same date was 18.6 inches. Two addition- 

 al snow courses. Lower and Upper Farming- 

 ton Canyon, have been maintained in cooper- 

 ation with the Soil Conservation Service since 



RECURRENCE INTERVAL (Years) 



Figure 4. — Recurrence intervals of summer storms of various intensities and durations ranging 

 from 2 to 360 minutes. Curves are representative of that precipitation zone which includes 

 the upper Farmington Creek drainage. 



5 



