OVERFLOW OF RED RIVER OF THE NORTH. 
33 
The maximum storm precipitation that has been recorded for 
areas of 300 to 2,000 square miles occurred on July 20-22, 1909 (see 
fig. 13). The maximum 24-hour precipitation recorded for one sta- 
tion was 10.75 inches. Besides being maximum for the Red River 
Valley this storm, according to investigations made by the Miami 
(Ohio) Conservancy District, was one of the greatest that occurred 
in the upper Mississippi Valley during the period 1892-1916 and was 
the only one of 49 great storms in the northern portion of central 
and eastern United States that shows a precipitation in excess of 6 
inches in 3 days over a considerable area in the Red River water- 
shed. This storm was central over the watershed of the Wild Rice 
River in Minnesota and caused a more intense run-off to reach Twin 
Valley, Minn., than has been recorded on any other watershed of 
, 1 
\c 
~x 
V 
>s 
R 
s 
— 
A 
0,10 
10,000 20,000 30,0.00 
Area — Square Miles 
Fig. 10. — Depth-area curves for maximum storm precipitation on watershed of Red River 
of the North. A, Storm of July 17-22, 1897 ; B, storm of July 1-A, 1919 ; C, storm 
of July 20-22, 1909. 
similar size (835 square miles) in the Red River basin. This storm 
precipitation so far exceeded any other that has been recorded in 
the Red River Valley that it is doubtful whether any as intense as 
that will occur again within 75 or 100 years on an area of 800 square 
miles anywhere in the valley. 
Relative to the other 10 storms listed in Table 9, the records for 
several are of special importance. In some cases the heavy pre- 
cipitation covered areas from which the run-off was measured, while 
areas covered by some were outside the watershed to the east and 
southeast and no measurements were made. The storm of June 20- 
23, 1919, was central over Towner County, N. Dak. It was unusual 
in that the heaviest precipitation occurred in the northwestern sec- 
tion of the Red River watershed. The maximum 4-day precipitation 
was slightly more than 6 inches but that intensity occurred over a 
comparatively small area. This storm, however, caused heavy pre- 
cipitation over the Lake Traverse watershed. The records are meager 
but apparently on that area the rainfall was from 2^ to 4 inches in 
70352°— 22 3 
