The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1924-02-21

1917 and the return during the ir-
rigation season was SO per cent.
The Carmel record Is a means of
; six years discharge measurements at
z two to three-week intervals from
1918 to 1920 inclusive. The return
was 90 per cent during the irrriga-
ZION season. A small amount of
draln water was used within the dis
trict and is not included. The aver
age annual return per acre was IL
acre-ft. From January 1, 1915 to
May 81, 1916, the measurements
were made by the office of public
roads and rural engineering, U. s.
department of agriculture. From
then to December 81, 1920, the work
was carried on by the state en-
gineer's office every three weeks
with daily flows interpolated on ac-
count of the regularity.
The Rio Grande record is for the
year 1920. OF the total, SO per cent
OF the return is in the irrigation sea-
! son.
Between Whalen, Wyo., and
Bridgeport, Nebr., return waters
| from irrigation are pronounced. and
especially on the interstate unit of
the North Platte project of the U. s.
reclamation service, where consider
able artificial drainage has been
necessary to avoid water-logging.
In 1918 visible return flow from
the interstate canal and lands irrf-
gated from it measured in open drain
at their intersection with the Tri-
State canal amounted to 10000
acre-ft annually from 100000 acres
OF irrigated land, or LIS acre-ft per
acre per- year.
In 1918 and 1920 the return
waters to the North Platte river in a
25-mile section between Whalen
and Bridgeport amounted to 100000
acre-ft, annually. The soil on the
north side Of the river where rs per
cent of the irrigated area lies in very
sandy and porous; on the south side
the soil is from a sandy loan to a
clay loan.
Progressive Increase
AS to the increase in the return
flow over period of years, data
from published records of the state
engineers office and the Colorado
agricultural college are as follows:
The 235 mile stretch of the South
Platte from Platte canyon to the
Nebraska line increased in return
flow in the twenty year period from
1900 to 1920 from GA sec.-ft. to
400 sec.-ft. Similarly in forty-seven
miles of the Poudre from the canyon
to the mouth from 1900 to 1915 the
increase was from 10 sec.-ft. to
175 sec.-ft. The entire South Platte
area, including both main tributaries
from the foot of the mountains to
the Observation-Disclosures line from
1900 to 1910 increased from 1,201
sec.-ft to 1866 sec.-ft. The Arkansas
river from Canyon City to the Colo
rado-Kansas line, 215 miles, in a
seventeen-year period beginning in
SAT sec.-ft. The return flow in the
river from Bachelor to
The mouth at Delta, fifty-three miles
in 1900 was eighty-nine sec.-ft. and
years later had increased
to $50 sec.-ft
Return flow waters from irriga-
lion along the Salt and ella rivers
we're well in evidence fifteen to
.wenty years ago. Soil texture,
slopes and narrow irrigated areas
llong the river combine to produce
immediate and pronounced seepage
water. In the Salt river valley 80
,er cent of return flow has been OBJ
erved, and along the upper ella
liver 65 per cent. In 1900 $50 sec.-
t. or about 10000 acre-ft. annu-
lily were reported between Tempe
nd ella Bend.
Drainage Recovery
Drainage has become an import
mt problem to most irrigation pro-
ects. In 1920 the u. S. reclamation
ervice expended $996,000 on drain
ge in connection with it's various
projects (see Reclama-
ion Record, March, 1921, page
Oh
The San Luis valley lies on the
eadwaters of the Rio Grande In
outhern Colorado. The valley is an
Id lake bed and is consequently very
at, and has poor natural drainage.
.arge areas have become water
ogged and alkalied, both irrigated
nd unirrigated. Approximately
100000 acres of raw and irrigated
and need drainage relief in some
orm. Drainage districts have been
rganized and constructed. The
,armel districts there is a return of
GLOWING data will be of value. For
he 1 2 acre-ft. per acre drained (six-
ear record.) The duty is roughly
acre-ft. per acre. In the Rio
Irande district just completed, the
eturn is close to one acre-ft. per
ere drained. 1t should be noted
hat sub-soil conditions are favorable
0 drainage and in ordinary years is
sed freely.
Summary
The following paragraphs sum-
larize the conclusions of this study:
1. Ordinarily SO per cent Of the
1ater diverted for irrigation pur-
oses becomes a source of return
ow.
2. Annual return flows of from 35
> SIS per cent of the river flow d.
erted have been measured for large
ompact irrigated areas.
g. In the South Platte and tribu-
ary valleys in Colorado, where L.
90, 900 acres are irrigated, return
ow amounts to 100000 acre-ft.