SEEPAGE OR RETURN WATERS FROM IRRIGATION. 
5 
has had the effect in some places of filling in the ground until in> 
some places the water shows on the surface, water-logging or seeping 
the ground, rendering it unfit for cultivation and capable of grow¬ 
ing only sedges, cat-tails, and other water-loving plants. Sometimes- 
on the evaporation of the water, a deposit of alkali is left, render¬ 
ing the land unfit for cultivation without draining. These effects 
are found underneath the lines of ditches, so that many companies 
insert clauses in their contracts for water or for right-of-way freeing 
the company from liability for damage of such nature. In other 
cases where contracts do not prevent, it has given rise to suits for 
damage from such cause. 
The water usually first appears near the canal, and progres¬ 
sively farther away year by year. 
§ 5. The phenomenon has been but little studied. The rea¬ 
son has doubtless been that in most countries irrigation is of such 
age that there is no record with which to compare the condition 
now and before irrigation, and the changes due to the construction 
of canals have been lost in the centuries which have elapsed. 
There is, however, land in Lombardy which is manifestly seeped and 
water-logged, and has every appearance of being due to irrigation, 
Pavia Canal, between Milan and Pavia, built in the early part of 
this century, has damaged much land. There is loss from the 
canals themselves, as w^ell as from the water which is applied to 
the soil. 
Wherever the conditions before the construction of canals are 
within the range of memory, the fact has been observed to a greater 
or less extent. 
Year by year the effect is found farther and farther aw^ay from 
the canal, or from the irrigated locality, as the case may be. In 
course of time, the waters wdiich are percolating through the subsoil 
reach the thalweg or the depression of a “ draw,” or a river, and 
increase the waters passing therein. 
It, therefore, happens that the depressions or draws, which in 
Colorado are usually dry before irrigation is practiced, contain liv¬ 
ing streams after irrigation has been carried on for some time. 
While the Poudre river varies during the year from a maximum of 
3,000 to 5,000 cubic feet per second to a minimum of 50 to 
100 cubic feet per second, or may vary by forty to eighty times the 
minirnun flow, and other streams correspondingly, tliese seepage 
waters will not often vary twice their minimum flow. In consequence 
the water rights in the seepage channels are usually considered 
more valuable than those in the river waters. 
The particular places at which the waters come to the surface 
will generally be determined by the nearness of the underlying rock. 
Frequently the water shows in a particular locality, so that there is a 
