The Lee County journal. (Leesburg, Ga.) 1904-19??, 1907-08-02
IRRIGATION RESERVOIRS.
Estimates Of Losses from Them by
Evaporation.

tens III this country are owned anu
managed by private companies, ana
were constructed by them. Other big
enterprises Of the same kind VIII be
made possible by what is known as the
Reclamation Service Of the national
government. Money derived from the
sale OF public lands is being lent for
the damming of streams in the ara
regions Of the country, with a view
to irrigating land which cannot now
be cultivated Provision is made for
repayment to the federal authorities
of the sums expended in this work, but
as they have undertaken the respon-
sibility they naturally want to know
how much good it will DO. At present
no less than twenty-five projects Of
this sort are under way, and have
reached various stages of advance
ment. These are expected to open for
irrigation 3,19S,O00 acres of land, and
call for the expenditure Of about SAL
100000. The largest of the reservoirs
will be in Arizona cat Roosevelt), and
the dam which creates it is by far the
highest in the world. That one under
taking will cost about $6,500,000 and
it is expected to supply water for fully
100000 acres.
By measuring the flow of stream,
engineers can ascertain pretty accu-
rately the quantity of water which
passes a given point in year. To as
sumo that that amount could be en-
ployed for irrigation, however, would
not be quite safe, because evapOra-
ton from a reservoir might be greater
than from a narrow stream. At any
rate, there would be a considerable
loss where the climate is dry, for dry
air has, remarkable appetite for mois-
ture, Hence, it is important to de-
termine beforehand how big a supply
can be expected, and how heavy the
losses will be from this one cause. EX-
perts think that from the Roosevelt
reservoir the evaporation will not be
less than six feet a year, or enough to
diminish the area benefited by the
pond to the extent of something like
$4,000 acres. The estimates made in
that one instance and in regard to the
other reservoirs are probably pretty
near correct, but they may not be ex-
act. To some extent they seem to in
volve guesswork. Hence, any new
source of information will be welcome,
both to the government and to the set
tiers whom it is aiming to help.
A chance to get some light on the
subject has been afforded in Southern
California by accident, or, rather by
series of accidents. Breaks in the west
bank Of the Colorado river within the
last eighteen months have caused sue
sive foundations in the Salton basin.
Attempts have been made to check the
invasion by filing the openings in the
bank, the last one having ended only
two or three months ago. However,
an immense shallow inland sea has
been created, and even if there be no
fresh addition, the present accumula-
ton will probably not dry up for sew
eral years. An effort will be made to
measure with accuracy the rate at
which the level subsidies, and thus to
determine the rate Of evaporation. The
Salton Sea has no outlet, but is like
the Dead Sea and Great Salt Lake.
If the latest repairs made in the
banks Of the Colorado withstand the
early summer foods, now nearly due,
observations will be begun, continued
for at least two or three years, and
perhaps extended over a still longer
period The temperature, atmospheric
dryness and wind movement there
may not be identical with those at the
sites of Uncle Sans own reservoirs,
but when the loss from evaporation in
that one locality has been ascertained,
figuring about the others ought to be
easier than it is now.-New York Trib'
une.