THE DAM 55 
supply. The president of the company stated that he esti- 
mated the value of this water to fruit growers along the 
Minnesota and North Fork valleys at not less than $15,000, 
as it practically saved the fruit crop on every orchard that 
was depending on this irrigation project for water. This 
meant a little over $1,000 for each of the fourteen dams 
tapped.” 
DAMAGE CAUSED BY BEAVERS 
I have mentioned the uses of beaver dams, and it is only 
fair to look at the other side and say something about 
the damage caused by beavers. The damage to lands by 
flooding is probably slight as a rule, though sometimes 
western farmers complain of their meadows being flooded 
by beaver work (Figs. 23, 24 and 25). 
Possibly the most serious damage is that caused to timber 
by flooding, of which Johnson has made a study in the 
Adirondacks, and this in spite of the complaints which were 
made, does not appear to be as serious as some of those op- 
posed to the beavers claimed. It so happens that my own 
observations show comparatively little of this damage. 
While I have seen many trees thus killed, by far the greater 
portion have been aspens, alders and willows, which are not 
considered of any particular value. The commercial value 
of the pines, firs and spruces which I have seen destroyed by 
beaver ponds would be small, though they sometimes made 
a rather conspicuous showing when standing in a pond with 
their brown tops contrasting with the green living trees 
about them. Besides flooding there is also the damage 
which may be done by cutting down trees or girdling them, 
though this is little compared with that done by flooding. 
Dr. C. E. Johnson has made what is probably the closest 
study of such damage with the object of arriving at some- 
