IOWA ACADEMY OF SCIENCES. 
145 
A recent government report states that in studying the 
rainfall with reference to reservoirs it has been found 
advisable to divide the year into three periods: for storage, 
growing and replenishing. From our own data on rain- 
fall we find the following result for one square mile: 
CATCHMENT AREA, ONE SQUARE MILE. 
Minimum Average 
Rainfall. Rainfall. 
Storage Period, Dec. — May, 182 days 6.36 inches. 
Growing Period, June — Aug. ,92 days 2.64 inches. 
Replenishing Period . Sept. — Nov., 91 days I 2.9.S inches. 
12.48 inches. 
11.88 inches. 
6.41 inches. 
• One inch of rainfall over a square mile of surface gives 
17,378,743 gallons. The local precipitation in gallons for 
the storage, growing and replenishing periods is as follows: 
Minimum Rainfall. 
Average Rainfall. 
Storage Period , 
Growing Period... , 
Replenishing Period 
88,457,802 gallons. 
4,518,473 gallons. 
12,165,120 gallons. 
216,886,713 gallons. 
20 , 680 , 704 gallons. 
26,415,689 gallons. 
Our city even now with a water supply not generally 
acceptable is said to use about 75,000 gallons per day in 
addition to the large amounts from cisterns and wells, 
while the supply that is looked for is 3,500,000 gallons. 
In Boston the water used was 119 gallons per inhabitant 
per day in 1903. 
On this basis the present amount required for Indianola 
would be 416,500 gallons per day, but plans for the future 
should allow for possible growTh. We know that prior to 
the installation of water works the people of our city did 
get along with the rainfall, though it was frequently em- 
barassing as wells and cisterns frequently give out. In 
the drought of 1895 there were fears of a serious conflagra- 
tion. When the supply is not carefully treasured in cis- 
terns and doled out by the dipperfull, a much larger supply 
is necessary. Then, the greater the drought the larger the 
amount of water used for streets, lawns and gardens, and 
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