s 
IOWA ACADEMY OF SCIENCE 
Arey informed me recently that in case of high water, although the city 
water was turbid, the water from the spring remained., clear. He be- 
lieves that the contamination probably occurred entirely while jthe 
water was being conducted from the spring to the collecting system at 
the pumping station through an old wooden conduit buried in the ground 
subject to overflow from the river. The fact, however, that the’ number 
of bacteria in the water directly from the spring varied from 40 to 480 
per cubic centimeter and that the water in many of the neighboring deep 
wells with pipes extending into the limestone of the surrounding country 
becomes turbid in times of high water, would indicate that there is some 
contamination of the water through the fissures in the rocks with ma- 
terial of the neighboring stream or surface soil. 
It is worthy of note that the public generally regards all spring water 
as pure. The people of Cedar Falls were astounded when it was an- 
nounced that their water supply was the source of the infection. When 
in 1904, after Waterloo had experienced an epidemic of typhoid fever, 
that city was casting about for a new water supply, many of the citizens 
suggested the construction of an aqueduct to the spring at Cedar Falls. 
THE FORT DODGE EPIDEMIC. 
An epidemic of typhoid fever occurred at Fori Dodge, during the 
summer and fall of 1912. About 100 persons were affected by the 
disease of whom four died. 
The water supply of Fort Dodge comes principally from the deep 
wells. They also take the water from pipes beneath the river. The 
source of infection was apparently from both the pipes beneath the 
river and from one of the deep wells. The feature of interest is in 
connection with the latter. This well (Well No. 1) which was the first 
of the three wells as also the deep stone— being 1,827% feet deep and 
extending to the Jordan sandstone, was started at the bottom of a large 
shaft which was constructed several years previously for the purpose 
of supplying the city with water. This shaft which measures 10x10 feet 
across extends down for 90 feet. From the west side of the lower end 
of this shaft, a tunnel, 9 feet in diameter, was extended under the Des 
Moines river. This tunnel was driven in sandstone, so required but 
few timbers for support, whereas the shaft has a wooden casing for 
almost its entire extent. The shaft extends successively from above 
downward through the following layers of earth: 
