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2 , , , ,l..' .-:~ <:':.:' (J1 r>.~ '-Jl he arrived by an equal or greater amount, thus causing no change in the stream flow say at Lee Ferry. HYDROLOGICAL CYCLE IN THE: COLORADO RIVER BASIN (Exhibit 1) , To adopt the Hydrological Cycle as a logical occurrence in the Colorado River Basin, several aasumptions need to be made, the validity of which, in most cases, is self-evident. These assumptions are: 1. That man cannot destroy water. He may change its form and loca- tion but not destroy it. ~. Tbat precipitation and wind movements ar~ sul;lstantially the same now as before man's advent into the Basin. 3. That nature operates a complete hydrological cycle intbe Basin and has #ne so since time began, i. e.. moisture-laden air is bloWtl over land from the ocean and precipitated when conditions causing. conden- sation are met. This precipitationi~~;\l!'!LE!Y"'1!Q!'~~!c:L~!tt;be~~i.ll,- uVhctc. tun l"den air again precipitate"S"tlie'moisture when further favorable . . conditions for condensation are met. Surplus waters are carried back to the ocean in surface streams and underground channels to beevap- orated in transit and after arriving at the ocean. portions of the rain- fall are evaporated from falling on vegetation and then transpiration by vegetation. A very small portion goes to make up the fiber of the . vegetation growing in the area. .. 4. Und"r this concept. the fact that man hasccincentrated surfaclil runoff on relatively small areas of the Basin, either by irrigation of landS or by the construction of reservoirs to store water, means that he has only increased the moisture c::ontent of the air passing over these areas. If this air passing over these particular areas moved out of the Basin and precipitatlild its moisture outside the Basin before man. it is doing so now and the increase in evaporation from such areas is lost to the Badn. On the other hand. if the air moving over these areas before man. precipitated its moisture within the Basin, it is doing the same today. Since it is evident that the Colorado River Basin in Colorado is. as nearly a closed basin as could be found in nature, the chances of ah' currents laden with moisture picked up in the Basin, passing out of the Basin is very remote. Plate 1#2. is a profile of the perimeter of the Upper Basin. It is a fad that few if any western slope storms ever get over this divide, so it is possible that practically all the moisture picked up in the Basin could be precipitated on the Western Slope within the Basin. It appears to be far more reasonable to assume that the 884, 091 acre feet -17-