8 BULLETIN 304, U. S. DEPARTMENT OF AGRICULTURE. 
the United States has led to an earlier activity in drainage reclama- 
tion than has existed in most other portions of our country. The 
results of adequate protection and drainage are shown by figure 1 of 
Plate IV, a view of part of a tract of reclaimed land on the Illinois 
River. 
SIZE OF PUMPING DISTRICTS. 
In order that the building of a levee around a tract of overflowed 
land and the installation and operation of a pumping plant may be 
carried out economically at a moderate cost per acre of land re- 
claimed, it is necessary to have a considerable area included in a 
single project. Hence, ordinarily the land does not belong to a 
single owner, but rather to a number of individuals. In order that 
all the interested landowners may work harmoniously together it is 
necessary, first, that an incorporated drainage district be formed 
according to the method provided by the specific laws of the par- 
ticular State relating to this subject. The officers of the district so 
formed may then proceed to carry out the successive steps necessary 
in the inauguration of the construction work. 
Pumping districts of as small an area as 3,000 acres may profitably 
be formed in favorable locations; but, in general, the expense per 
acre is less as the district is larger up to a certain limit beyond which 
there is no further advantage from increased size. According to 
experience, about 10,000 acres of reclaimed land seems to be a very 
satisfactory size for such a district. 
However, the boundaries of a district are determined largely by 
the natural surface conditions. A district will naturally include all 
the land on one side of the river between the channel and the bluff 
and extending up and down the valley from one tributary to the 
next of any size entering the river on the same side. The tendency 
in recent years has been to make the districts larger and to extend 
them beyond the so-called natural boundaries — the tributaries to the 
river — by diverting these streams around the district or by carrying 
them by means of levees through the district to the river. The 
internal drainage channels are carried under these diversion channels 
by means of concrete inverted siphons or culverts. By this increase 
in area of the lands organized in one district the expenses per acre of 
organization and administration during construction and operation 
are materially reduced. The charge per acre for operation of pump- 
ing plant is, in general, much less on the larger district. As the 
valley ordinarily has the same slope as the high-water line of the 
adjoining river, the lift of the pumps in forcing the drainage water 
into the river is very rarely increased by extending the district a 
greater distance along it. On the other hand, smaller' districts are 
being now reclaimed than formerly was the practice. This is due to 
the increased demand for land, which makes reclamation profitable 
