CHAPTER IV 

 INVESTIGATIONS IN COLDWATER CANYON 



By Colin A. Taylor and Harry G. Nickle* 



In many instances water supplies for irrigation, domestic, and 

 industrial uses are diverted from the lower reaches of canyons and the 

 water is allowed to flow through many miles of open channel bordered 

 by growing vegetation. A large portion of the water used originates 

 in the mountain watersheds and must pass through the canyons before 

 it reaches the irrigated areas of the valleys. There is little information 

 available as to the amount of water lost in such canyons through 

 evaporation and transpiration from the native vegetation. 



Losses from the moist land bordering the lower sections of Temescal 

 Creek, four miles southeast of Corona, were investigated by the Divi- 

 sion of Irrigation of the Bureau of Agricultural Engineering early in 

 1929. The growth was typical of the moist areas bordering the streams 

 in the valleys, with willows and tules predominating. The results ** 

 indicated that large losses must occur from similar growths along the 

 Santa Ana River and that the supply of water diverted in the lower 

 Santa Ana Canyon for irrigation in Orange County must be consider- 

 ably diminished because of the loss of water in the moist areas 

 adjacent to the river. 



Since the losses from the areas supporting willows, tules, and 

 kindred moist land growths were indicated to be of considerable magni- 

 tude, it was deemed advisable to extend the study to canyon reaches 

 in which alder growths predominated, above the usual points of diver- 

 sion from the streams. It was the purpose of this study to obtain data 

 on the loss of water during the growing season by evaporation and 

 transpiration from a typical small canyon and on the amount of addi- 

 tional water which might be derived were the water supply diverted at 

 a higher point on the stream. 



The experimental data for this stud}' were obtained in Coldwater 

 Canyon, located near ArroAvhead Springs in the San Bernardino 

 Mountains in the upper basin of the Santa Ana River, approximately 

 7 miles north of the city of San Bernardino. This canyon was chosen 

 as being representative of many of the smaller canyons of southern 

 California. 



The data were collected during the growing seasons of 1931 and 

 1932. In 1931, two bedrock stations, hereinafter called "controls," 

 were installed in the canyon. The "lower control" was located about 

 one mile above the mouth of the canyon, and the other, designated as the 

 "middle control," was located 2090 feet upstream from the lower 



* Prepared by C. A. Taylor, Assistant Irrigation Engineer, and Harry G. Nickle, 

 Junior Hydraulic Engineer, Bureau of Agricultural Engineering, U. S. Department 

 of Agriculture. 



** "Rainfall Penetration and Consumptive Use of Water in Santa Ana River 

 Vallev and Coastal Plain," by Harry F. Blaney and C. A. Taylor, State of California, 

 Department of Public Works Bulletin No. 33, Chapter IV, 1930. 



(SS) 



