514 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1919. 
The distribution of reclaimable agricultural land is very irregular 
and erratic. The Lake States, the southern Atlantic, and the Gulf 
States contain vast areas of lands requiring drainage and also tim- 
berlands, the majority of which have been at some time or other cut 
over and a large proportion of which would be suitable for agricul- 
ture if properly cleared. It by no means follows that all of such lands 
should be now or eventually devoted to agriculture. 
In many places the swamps and overflow lands serve useful pur- 
poses as reservoir sites to diminish the volume and intensity of the 
floods of the drainage basins in which they occur, and each one should 
be carefully considered as to the advisability of continuing its serv- 
ices and improving its efficiency for these functions. The regulation 
of streams is important from many points of view. If our streams 
could be made to flow with comparative regularity instead of in great 
flood waves, it would terminate destructive floods that cause such 
havoc and loss of life. To accomplish this we must carry out gigantic 
projects, such as those in the Miami conservancy district in Ohio, 
designed mainly or exclusively to moderate the freshets and regulate 
the flow of the streams. 
The feasibility of such works depends largely upon the existence 
of suitable reservoir sites. 
A good reservoir site is in several respects a topographic rarity. 
It must ordinarily have a suitably located basin, with a sufficient 
watershed above, which can be closed and formed into a reservoir 
by a feasible dam of moderate cost which will form a reservoir of 
large capacity in order that its usefulness may be commensurate 
with its cost. Where such favorable reservoir sites exist they may 
be of great value and may constitute the key to the feasibility of 
river regulation, and if reclaimed for agriculture and built up with 
towns, villages, railroads, and other improvements, their cost soon 
becomes prohibitive, and the only feasible opportunity of river regu- 
lation may thus be destroyed. Every scheme for the drainage and 
reclamation of swamps and low-lying river bottoms should therefore 
be carefully considered in its relation to the country at large, and 
especially that below on the streams to which its waters are tribu- 
tary, and if the proposed reclamation will in fact destroy a good 
and useful reservoir site, it should not only be avoided but pre- 
cautions should be taken to prevent the accumulation of improve- 
ments which will become obstructions to its utilization for storage 
purposes. This principle is far more important than usually real- 
ized, because we are apt to overlook the need, the rarity, and the 
essential characteristics of feasible reservoir sites. 
Similar precautions are necessary in examining areas of timber 
or cut-over lands with reference to the wisdom of clearing and de- 
voting them to agriculture. Some lands are so hilly and rocky as 
