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(hlJ2J~ 33 Er,rpr.s .of ,admlnistratian Conditian and number .of dams Transpiration by plants Irrigation practice alang river Past Studies In 1938 M.C. Hlnderllder, (23)' while State Engineer, presented a paper entitled "Determinatl.on.of losses Pr.operly Chargeable ta Flows .of Water Re- leased fram StDrage ReservDirs and Transmauntaln Diversl.ons" where he listed 17 majar factDrs affecting Joss of reservoir water In transit. (The 17 fac- tors are included in the above list). He dl,scusses these factars In part by stati ng, "These fact.ors' alone, through hundreds .of different combinatl.ons and changes daily Imposed by the elements .of nature, may praduce a milli.on different results having a direct bearing .on this complicated prablem. Even thllUgh'lwe had an accurate knowledge .of the major physical canditions just mentioned, we have a cantralling effect upon stream fl.ow losses or accreti.ons, which It is nat passible t.o attain, due to the cantinual change in such fac- tors, the prDblem is nat susceptible to mathematical determinatian. This partIcular prablem in its simplest aspects is the most difficult .one with which the water .officials have to deal, and is growing more difficul't wi th the rapid Increase In the pr.ogress being made in the conservatian of .our natural water supplIes, through reservoir construction, transmountain diver- sions, and exchanges between ditches and reservairs and natural stream fl.oW. All .of these fact.ors are seri.ously affected frDm time ta tIme by periodic changes in the hydrDl.ogic cycle, and in the narmalcy .of the rate and am.ount of preclpltatiDn, which have profound effects upon the underground water table, .of a drainage basin, and the rate and amaunt of return flaw trIbutary to any natural water course." He goes an to state "Due to the importance of the prablem under cansld- eratian the State EngIneer has made many attempts ta determine the loss of reservDir water turned inta a natural stream. With but few exceptians, the results of such attempts have nat been very conclusive, and in fact have been cDnflicting, due to twa principal reasons. First, practically all streams flowing thrDugh an irrigated region show an increase or gain In natural flow progressively frDm their upper tD the IDwer reaches thereof, due to return flow. Hence, it is impDsslble tD determine what losses, If any, .occur due tD increases in the stages of flDw, such as result where the natural flaw is augmented by reserVDir releases. The .only thing disclased by such measure- ments from a stream~Durce tD its terminus is the net diff~rence between gross gain and grass loss, which as stated, 'usually shows up in the f.orm of a net gain~1J In cDncludlng his paper, Mr. Hinderllder sums up what he feels ought tD be in the future. "I have been giving this matter much thought, and am in- clined t~ believe that a mare ratianal methad of determining reservair losses, , , based upon sclenflflc data, is possible .of develapment and application. The callectlon of the necessary basic facts. however, would require the expend- iture of several thausands .of dollars, and this would not provide a solutiDn of the dIfficulty withaut addltianal funds far rigid pDlicing .of the streams day and night. Such plan would require careful surveys .of the stream tD de- termine the area .of expDsed water surfaces from point to pDint, the elevation of the water table a<ljacent tD the stream cha'1nel, the rate ar,<l quantity of invisible inflow, the frequent sectionalizing of the river with gaging sta- tiDns equipped with autamatic recorders at each statlan, e~tablishment of