UTAH ACADEMY OF SCIENCES 197 
place southeast of Kanab, Utah, was in a region mostly 
bare, but supporting some sage brush and greasewood. 
The rainfall from previous storms had been impounded 
by throwing a dam across an arroyo. This pool was so 
befouled by the collection of all the debris for many rods 
roundabout that stock drank from it reluctantly. 
Cloudbursts, socalled, are reported more frequently 
from certain sections than formerly, though this is prob- 
ably not so much a fact about the rainfall as about the 
condition of the watershed. A badly denuded water- 
shed sheds its water abruptly and after heavy rains it 
accumulates with great rapidity and great power, befoul- 
ing the water supply temporarily, silting reservoirs detri- 
- mentally, and endangering controlling works and other 
improvements in the path of the flood waters. Settling 
tanks are thus necessary in handling Salt Lake City’s 
water supply originating in thinly forested watersheds. 
An important instance of the effect of a denuded 
watershed in causing floods occured near Salt Lake City 
July 24, 1916. The shower at the Weather Bureau gage 
in Salt Lake City business district amounted to 0.43 inch; 
at the University on the east bench, 0.35 inch, and at the 
High Line intake in City Creek five miles northeast of 
the city, 0.85. 
Assuming with reasonable safety that the storm over 
the adjacent mountain slopes was fairly uniform in City 
Creek and in Dry Canyon next to the south, the latter 
should have shown a lighter discharge of water, all 
other things being equal, because it is shorter, heads 
lower, and consequently would receive much less precipi- 
tated moisture. 
As a matter of fact, the flood was so great in Dry 
Canyon, where forest and brush areas are scanty, and 
where grazing has been continuous many years over the 
lower sections, that several cattle were destroyed, and 
the bodies of some animals were washed out of the can- 
yon. The roadways were also badly damaged. In City 
Creek, where there has been no grazing for many years, 
and the brush and vegetative cover has become compara- 
tively heavy, and small areas of forest remain, the runoff 
from the storm was so light, as measured twice a day at 
the intake, its presence in the records was not observed. 
