IRRIGABLE LANDS OF THE SALT LAKE DRAINAGE SYSTEM. 123 
Thus it appears that if all available lands on the upper Provo are 
reclaimed, one-third of Utah Valley must go unwatered, while if none of 
them are irrigated, nearly the whole of the valley will be supplied. A 
middle course would appear most wise, and will undoubtedly be followed. 
A eradual extension of the canals, as the demands and means of the com- 
munities dictate and permit, will bring lands successively into use in the 
order of their value and convenience, and when the limit is reached and 
title has been acquired to all the water, the most available lands in each of 
the three valleys traversed by the Provo will have been reclaimed. The 
residents of Kamas Prairie will probably have increased their meadows so 
as to furnish winter hay for herds sufticient to stock the summer pastures 
of the vicinity; Provo Valley, having a less favorable climate than Utah 
Valley, will have irrigated only its choicest soils; and the major part of the 
river will belong to Utah Valley. The apportionment may be roughly 
estimated as—Kamas Prairie, 10 miles; Provo Valley and Waldsburg, 20 
miles, and Utah Valley, 70 miles. 
Below Utah Lake there is little inequality of volume dependent on 
season. The lake is a natural reservoir 127 square miles in extent, and so far 
equalizes the outflow through the Jordan that the volume of that stream is 
less affected by the mean level of the lake than by the influence of north- 
erly and southerly winds. With suitable head works its volume can be 
completely controlled, and, if desirable, the entire discharge of the lake 
can be concentrated in the season of irrigation. 
The highest stage of the lake is in July, and the lowest in March or 
April; and the natural volume of its outlet has of course a corresponding 
change. In July 1 found that volume to be 1,275 feet per second, and I 
am informed by residents that the stream carried more than one-half as 
much water in its low stage; 1,000 feet is perhaps not far from the mean 
volume. When all possible use is made of Provo River and other tribu- 
taries the annual inflow of the lake will be diminished by about one-eighth, 
and the outflow by a greater fraction, which we will assume to be one- 
quarter. (This postulates that the evaporation is at the rate of 90 inches 
per year for the whole lake surface.) The remaining perennial outflow of 
750 feet per second, if concentrated into four months, would irrigate for 
