20 DIVISION OF WATER RESOURCES 



water is very liiyli. Linin<>' canals to check see})a^'e losses and' diverting 

 stream flows into conduits conserve water by eliminating losses due to 

 such aquatic growths as well as by decreasing the seepage. 



In many instances irrigation and domestic supplies are obtained 

 by diverting water from the lower reaches of canyons, the bottoms of 

 which usually are covered with vegetation. The amount of water lost 

 through consumptive use by that vegetation may be of considerable 

 importance where the flow of the stream is relatively small and studies 

 have therefore been undertaken to measure such losses. 



Evaporation records from standard Weather Bureau pans are 

 valuable in estimating evaporation losses from reservoirs and consump- 

 tive use of Avater by native vegetation growing in moist areas. Very 

 few data have been published on evajjoration in southern California, 

 accordingly all available records are included in this report. Among 

 these are those kept by the Bureau of Agricultural Engineering at 

 several stations in cooperation with the State Engineer of California 

 and those kept in other localities by local agencies. 



SUMMARY 

 Commencing in 1929 and continuing thereafter investigations of 

 evaporation and transpiration losses in moist areas have been conducted 

 by the Division of Irrigation, Bureau of Agricultural Engineering, 

 United States Department of Agriculture, in cooperation with the 

 Division of Water Resources, Department of Public Works, State of 

 California, and other agencies. Stations were established at Santa Ana, 

 Prado, San Bernardino, Victorville, Coldwater Canyon and Baldwin 

 Park. The results obtained are summarized in the following discussion. 



Santa Ana, Prado, and San Bernardino Stations 



Data regarding evaporation from bare uncultivated soil and use 

 of w^ater by noneconomic native growth found in moist areas in Santa 

 Ana River Valley have been collected for the three-year period immedi- 

 ately preceding May 1, 1932. Results of the first year's work have 

 already been published.* Investigations were conducted at three sta- 

 tions, although the greater part of the work was done at Santa Ana, 

 with smaller stations at San Bernardino, 50 miles distant, and at Prado, 

 midway between the other two. The Prado station w^as established a 

 year after the others and work there is being continued. The other two 

 stations have been dismantled. The soil at the Santa Ana station is 

 classed as a Hanford fine sandy loam** and that at San Bernardino as 

 Chino silt loam. The work at Prado did not include soil moisture 

 studies and the soil class was not determined. 



The investigation included studies of evaporation from soil, consump- 

 tive use of water by salt grass and Bermuda grass in tanks wdth pre- 

 determined water levels, use of water by tules and cat-tails in submerged 

 soil, and by willow and wire rush. Some experiments in evaporation 

 from water surfaces also were included. Soil evaporation and use of 

 water studies were carried on at Santa Ana in unbroken columns of soil 

 in 12 tanks and with disturbed soil in three tanks. All soil moisture 



* California State Department of Public Works Bulletin No. 33, Rainfall Pene- 

 tration and Consumptive Use of Water in the Santa Ana River "Valley and Coastal 

 Plain, bv Harrv F. Blaney, C. A. Taylor, and A. A. Young. 



** Soil Survey of the Anaheim Area, California. Bureau of Soils, U. S. Depart- 

 ment of Agriculture. 



