ae LANDS OF THE ARID REGION OF THE UNITED STATES. 
accept his results, it will be necessary to inquire in what way the white man 
has modified the conditions by which the water supply is controlled. 
To facilitate this inquiry, an attempt will be made to give a new and 
more convenient form to our expression of the amount of change for which 
it is necessary to account in the basin of Great Salt Lake. 
The inflow of the lake is derived chiefly from three rivers, and is 
susceptible of very exact determination. Thorough measurement has not 
yet been made, but there has been a single determination of each river and 
minor stream, and a rough estimate can be based on them. The Bear and 
the Weber were measured in October, 1877, and I am led by the analogy 
of other streams and by the characters of the river channels to judge that 
the mean volume of the Bear for the year was twice its volume at the date 
of measurement, and that of the Weber four times. The mean flow of the 
Jordan can be estimated with more confidence, for reasons which will appear 
in a following chapter. The ‘supply from other sources” mentioned in the 
table includes all the creeks that flow from the Wasatch Mountains, between 
Draper and Hampden, together with the Malade River, Blue Creek, the creeks 
of Skull and Tooele Valleys, and the line of springs that encircles the lake. 
mean 
Rivers, ete. 
Estimated 
Bear River, measured October 4, 1877, at Hampden Bridge.....-.---.-.....----.----+---2-+-------2---- 2, 600 5, 200 | 
\ieber River measured: October Li meariOrcdenee.--- one. Sea jak ole fe eee aerate mieereieieeeisiee 500 2,000 | 
POLGCANERUKON Mn eCASULEM diy tS eT Sane Np Cuma stelet =r etetetniclofetalate tase =taiaeteials wie tare a) atalsixtada}atal<falaiel=iatat=tstetetate 1,275 1, 000 
l:Shpplyatrom’other sources. sco ee sane e as acess: tee ceca: Fasonee eects yee aie me EER eee | 1, 800 | 
BOY bn aos nb hain Rad ante a SOD EO TOON Oe pb kc AO EO OBOOR CHSC SD ISDS asneSaanb a Sagnessasacoadad hoascoeds } 10, 000 | 
| Deduct the water used|inirrigation - == - 2 - oo eon nie a cln enn nw een nnn o| ona anna ss | 600 
Ie gui Cs Ae aches oe eee ee ee Seco as ae hab eet i one so sce eee ae eee ec | 9, 400 
Temainder 
The result expresses the mean inflow to the lake in 1877, and is prob- 
ably not more than 25 per cent. in error. The total inflow for the year 
would suffice to cover the lake to a depth of 60 inches. In the same year 
(or from October, 1876, to October, 1877) the lake fell 65 inches, showing 
that the loss by evaporation was by so much greater than the gain by 
inflow. The total annual evaporation of inflowing water may therefore be 
placed provisionally at 664 inches. If we add to this the rain and snow 
