292 FORESTS, RESERVOIRS, AND STREAM FLOW 
they actually increased the floods, while the people above complained 
bitterly of the back waters caused, throughout that low country, by 
filling the reservoirs so full. The water-powers immediately below the 
dams complained that they were not getting even the normal flow 
of the stream, which was the case. Navigation interests below St. 
Paul have always been lukewarm in regard to the beneficial effects 
of the reservoirs, and the Board was able to find only one steamboat 
captain who would make a positive statement that the boating interests 
derived any particular benefit from them. 
Some curious results developed in this investigation. It was found 
that, great as the reservoirs are, conditions may arise in times of 
excessive precipitation that will compel them to discharge a greater 
quantity of water than would flow from the lakes in their natural 
condition. That is, they might actually operate to increase the floods 
if they should fill to their limit during a period of excessive precipita- 
tion. This very contingency nearly happened in the season of 1905, 
as may be seen on the curve (Fig. 2) illustrating the effect of the 
reservoirs on the flood situation at Aitkin, Minn., about 130 miles be- 
low. On Fig. 3 is shown a comparison of the natural and regulated 
flow of the Mississippi below the three upper reservoirs, the latter being 
operated in the interest of navigation alone. These curves show very 
clearly that the natural flow of the river was more uniform than is 
the regulated flow. 
In like manner, during the period of lowest water, viz., in mid- 
winter, the reservoir gates are closed down to about 400 cu. ft. per 
sec., and the great water-powers, like those at the Falls of St. 
Anthony, are even worse off than in a state of Nature; but this draw- 
back is not as great as might be thought because the powers are able 
to utilize most of the storage when it comes during the period of 
navigation. 
Such are some of the complications and drawbacks which are 
encountered in this reservoir system and which would surely be met ina 
system built up under less favorable natural conditions. 
Nevertheless the Board found that the system was in itself a very 
great benefit and that the lack of appreciation of its advantages was 
for the most part due to ignorance of what they actually were. At 
the publie hearing the opposition fell. to pieces by the mere force of 
a better understanding, and it is safe to say that the system will 
