44 
GRAVEL AND PLACER MINING IN ALASKA. 
[BULL. 263. 
and 3,000 feet, and between the mine and the head of the creek, or its 
short tributaries. Of a total catchment area of nearly 75 square miles 
for American Creek, only 15 square miles are available for the opera- 
tions at the point referred to. If it were possible to catch all the 
water, say 11.4 inches in depth, which fell on this area during a 
season, and use it in hydraulic mining, it would amount to 1,500 
miner's inches available for one hundred and twenty days, and would 
move gravel at the rate of 1 cubic }^ard to the inch of water. As in 
practice it is not possible to utilize at head over one-third of that 
theoretically available in the catchment area, the capacity of the water 
power available is reduced in proportion. (See tig. 1.) 
Fig. 1. — Map showing American Creek drainage, Eagle district. 
In certain parts of the Fortymile region it is not impossible that 
water conduits from 10 to 15 miles in length can be constructed to* 
bring water to the placer diggings. The Glacier Mountains, lying, 
west of the upper portion of Mission Creek, rise to heights of 6,000' 
feet, or 3,000 feet higher than the general level of the interior country, 
and should afford a more promising water supply than any other area 
adjacent to the interior placer mining districts. The great drainage 
system of the South Fork of Fortymile Creek may also be available 
to a less extent for obtaining water under pressure. Miners should 
