Mr. Swain, 
376 DISCUSSION: FORESTS, RESERVOIRS, AND STREAM FLOW 
upon floods due to snow melting.” Would it not. be more correct to 
say that it was simply a perfect demonstration of the fact that even 
in densely forested areas there may be tremendous floods? 
Similarly, inconclusive, to the writer’s mind, is the statement about 
the flood of the American River compared with Puta Creek, in Cali- 
fornia. Water-sheds differ, not only as regards forests, but in other 
respects. The facts stated simply seem to show that in this case the 
forests did not regulate the flow to an extent sufficient to counter- 
balance other factors. For instance, if the writer is correctly informed, 
the slopes of the Sierras are steeper than those of the Coast Range. 
Again, the shape of the drainage area is a matter of considerable 
importance with reference to the maximum rise of water at a given 
point, as has been illustrated previously in this discussion. The author, 
of course, may be correct in his opinions, but his statements are 
entirely inconclusive. 
The logical position with reference to the forestry question is 
indeed quite similar to that of the author regarding the reservoirs on 
the Upper Mississippi. After showing that, as actually controlled, the 
flow of the river was less uniform than the natural flow (though it need 
not have been so), he concludes that the reservoir system “‘is neverthe- 
less a very great benefit.” Admitting, as the writer is ready to do, that 
a forest may conceivably increase the high-water stage in a given 
stream at a given point, it is yet safe to say that nevertheless the 
forests are a very great benefit as regulators of stream flow; and this 
conclusion is not shaken by the arguments of the author. 
It must be borne in mind that of all the influences which affect the 
uniformity of flow of streams, but two are subject to human control, 
namely, forests and storage. By preserving the forests and by building 
storage reservoirs it is possible for Man to regulate the flow and render 
it comparatively uniform. The preservation of the forests is the more 
important of the two, and should come first, because of the erosion 
and consequent filling up of reservoirs which results from deforestation. 
The preservation of the forests on the mountain slopes is especially 
important in the interests of navigation. Where they are destroyed, 
not only is the frequency and duration, and as a rule, the violence, of 
the freshets much increased, but fire often succeeds, adding to the 
evils by destroying the forest bed, and thus increasing the erosion. 
If the soil is thin, as in the White Mountains, or if it is fine and clayey, 
as in the Southern Appalachians, the results are almost equally bad. 
If, with the increasing demand for timber, these mountain slopes 
should be completely or largely deforested, the erosion and consequent 
silting up of our rivers and the impairment of navigation on account 
of floods and low waters, would be so great that there would be no 
doubt in anybody’s mind of the action of the forests. But it would 
then be too late, and many years would ‘be required to repair the 
damage, if it could be repaired at all. 
