DRAINAGE DISTRICT ASSESSMENTS. 17 
land must be considered. The following general factors, at least, 
should be considered : 
The need for drainage or the wetness of the land. 
The amount of drainage or protection furnished. 
Increased healthfulness. 
Increased accessibility. 
The use made of the property. 
The need for drainage, or the wetness of the land as this factor is 
called in some statutes, is the most important factor of benefit, for 
it includes many things and varies greatly with conditions. The 
amount of benefit usually increases with the wetness of the land 
or the frequency of the occurrence of flood water. These in turn are 
dependent upon the relative elevation of the land, the size, shape, 
and slope of the tributary watershed, the nature of the soil, the rain- 
fall, the temperature and humidity, the flora, and many other fea- 
tures. Because of the variety of physical conditions which affect the 
need for drainage many degrees of wetness are to be found, and 
since these conditions vary not only from one district to another but 
from one parcel of land to another it is impossible to establish a 
standard of the relative benefit to be expected by land arbitrarily 
designated as swamp, wet. or low. These varying conditions also 
make the averaging of the benefits over a district a matter of great 
difficulty, so much so that it is almost impossible to get a true average 
except in small and uniform districts. In considering this factor, 
due allowance must be made for all the advantages, either natural or 
artificial, which the land may possess and for any burden which the 
governing rule for surface waters may place upon it. 
The amount of drainage or protection furnished is a factor which 
can be subdivided into the completeness of the drainage furnished, 
proximity to the outlet furnished, and the sufficiency of the outlet. 
In overflow districts the improvement is seldom large enough to 
take care of all the water at times of extreme flood. It is generally 
more economical to permit the lands to be flooded occasionally than 
to provide complete protection against unusual floods. Where there 
is danger to human life in such overflows nothing less than maxi- 
mum protection is justifiable. Few open ditches or tile drainage 
systems are built sufficiently large to care for a maximum flood: 
yet assessors rarely consider the effect of floods. \Vhen such floods 
occur property in the district will not all be affected in the same 
manner nor to the same extent, so it is very necessary in making 
assessments to consider what the improvement will do. Drainage 
engineers are now able to predict the probable size and frequency 
of future floods in nearly all sections of the country, so there is no 
longer excuse for neglect to consider this element. 
Many drainage districts are planned to provide an outlet only, 
leaving the owner to install tile drains or whatever may be neces- 
sary to give complete drainage: other districts give complete drain- 
age to all or to a part of the land. 
The proximity of lands to the ditch or drain is a factor which is 
often improperly evaluated. The disadvantage of being at a dis- 
tance from the drain must be compensated for by more than the 
money cost of the connecting drain. The cost of a connecting drain 
depends on the distance from the tract to the drain, on the quantity 
6212i)—24 3 
