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0.4 m I Ie downstream from the U.S. HI ghwGlY 50 br i dge. There are 7 other stations on the main stem and 20 stations located on tributaries uP' stream from John Marti n Dam, some of which wereestab I i shed pr ior to 1900. The average annual flow of the Arkansas River at Las Animas. for the period 1939-59 is 185,300 a\=re-feet:. The annual flow varied from a minimum of 20,340 acre-feet in 1959 to a maximum of 1,022,000 .in 1942. The records are published in U.S. Geological Water Supply Papers. The highest known peak discharge at Las Animas Is 187,000 c.f.s., which occurred on June 4, 1921. 18. U. S. Highway 5.0 and the Arka,nsas Valley Branch line of the AHoSF Ra I Iway System cross the Arkansas River north of Las An imas. The U.S. Highway 50 bridge is a through-truss bridge, about 760 feet long with a 15-foot roadway. The Colorado State Department of Highways considers this bridge obsolete from a. traffic standpoint and has sched- uled Its replacement in the near future. The rai Iroad bridge, 858 feet long, consists of a central deck girder section with trestle sections. at either end. . 19. CLlMATOLOGY.- The cl imate of the Arkansas River watershed in Co I orado var i es. wide I y between the p I a I ns and the high mounta i nous reg Ions. Prec i p i tat ion averages from 12 Inches annua II y i nsome locations to rates of 20 to 40 inches over limited areas on the crests of the mountain ranges. The annual precipitation is quite evenly dis- tributed throughout the year in the higher elevations but a large percentage of the tota I I sin the form: of snow and some stat Ions have reported snowfal I during al I 12 months' of the year. Most of the annual precipitation over the plains occurs from Apri I through August. Las An Imas experi ences extreme temperature var i at ions. The max imum and minimum temperatures in 72 years of record are I 140 and -320. The mean monthly temperature varies from 30.90 in January to 79.60 in July and the mean annual temperature is 55.00. The average length of the growing season In the vicinity of Las ,Animas Is 155 days, which occurs between May and October. The average 'annual relative humidity Is 52 percent, varying from 38 percent at 5,p.m. to 70 percent at 5 a.m., as recorded at Pueblo. The average evapq>ration for the period Apri I through October is 65 inches at John Martin Dam. Wind data recorded at Pueblo indicate the preval I ing direction to be from the west at an average velocity of 8 miles per hour. The maximum speed recorded was 80 m.p.h. in January 1950. 20. The precipitation records for Las Animas, dating back to 1867, are ,the mOst complete and extensive records of any In the Arkansas Valley. The annual precipitation has varied from a minimum of 2.79 inches in 1894 to a maximum of 21 .39 Inches in 1923, averaging 12.35 inches per year tor the period of recprd. The month of July has the highest average monthly rainfall (2.09 inches); but the greatest amount ever recorded during anyone month is 7.54 inches, which occurred During Apr I I 1900. The max i mum da i lyra i nfall of 3.60 inches occurred In Ju I y 1958. Snowfall at Las Animas averages 20.1 inches, annually. . 8.