WATER SUPPLY. Es) 
The treading of many feet at the bogey springs compacts the spongy 
mold and renders it impervious. The water is no longer able to percolate, 
and runs away in streams. The porous beds of brooklets are in the same 
way tramped and puddled by the feet of cattle, and much water that 
formerly sank by the way is now carried forward. 
In all these ways the herds tend to increase the inflow of the lake, and 
there is perhaps no way in which they have lessened it. 
3. The cutting of trees for lumber and fence material and fuel has 
further increased the streams. By the removal of foliage, that share of the 
rain and snow which was formerly caught by it and thence evaporated, is 
now permitted to reach the ground, and some part of it is contributed to 
the streams. Snow beds that were once shaded are now exposed to the 
sun, and their melting is so accelerated that a comparatively small prapor- 
tion of their contents is wasted by the wind. Moreover, that which is 
melted is melted more rapidly, and a larger share of it is formed into rills. 
On the whole, it appears that the white man causes a greater per- 
centage of the precipitation in snow fo be melted and a less percentage to 
be evaporated directly. This follows from the destruction of trees and of 
grass. By reducing the amount of vegetation he gives a freer flow to the 
water from rain and melting snow and carries a greater percentage of it to 
streams, while a smaller percentage reaches the air by evaporation from the 
soil. By the treading of his cattle he diminishes the leakage of the smaller 
water channels, and conserves the streams gathered there. By the same 
means and by the digging of drains he dries the marshes and thereby 
enlarges the streams. In all these ways he increases the outflow of the 
land and the inflow of the lake. He diminishes the inflow in a notable 
degree only by irrigation. 
The direct influence of irrigation upon the inflow is susceptible of 
quantitative statement. Four hundred square miles of land in Utah and 
Idaho are fertilized by water that would otherwise flow to the lake, and 
they dissipate annually a layer of about 20 inches. To supply these 20 
inches the drainage district of 16,0060 miles yields an average layer of 0.5 
inch, and this yield is in addition to the 1.4 inches_required to maintain 
the increase of lake surface. The total augmentation of the annual water 
