PUB00068

• Year: 1952
• Title: A Hundred Years of Irrigatioin in Colorado, 100 Years of Organized and Continuous Irrigation
• Author: CWCB
• Description: Irrigation history of Colorado
• Publications - Doc Type: Historical

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On the PourJ.re River about 30 percent of the vmter applied in i.rri..
gation returns to the. river."

These conclusions have since proved to De substantially in line
with the findings of later seepage investigations.

These early studies of return flow on the Poudre and South Platte
Rivers were extended to other Oolorado streams where the findings were
more or less: in accord with the original investigations'. This pioneer
work in Colorado has, over the years, been applied to practically all
the irrigated areas of our ~Jestern States and is now, no doubt, the
basis of estimating the water supply in many foreign lands.

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The importance of return flow to the irrigator .is forcibly brought
to our attention in the case of the lower reaches of the South Platte
Valley in Colorado. In the beginning this area was sparsely settled
and the irrigation supply meager. As late as 1902 the irrigated area
in this section of the Platte Valley was about 100,000 acres and was
then considered to have the poorest water supply of the whole valley.
By 1926, the acreage had .increased to about 250,000 acres and the water
supply raised to ~le point of full accommodation of all appropriated
irrigation rights along the river. This satisfactory condition resulted
wholly from the increased supply due to return flow as concluded from
studies made by Ralph I. Meeker.

The large storag8 reservoirs in the lower South Platte Valley are
almost entirely filled Hi threturn flow accumulations throughout this
section of .the stream.

Ivan E. Houk, in his new textbook "Irrigation Engineering," reports
the result s of a study of return flow records on file in the office of
State Engineer Hinderlider. These records .cover many years of seepage
investigations on the South Platte between Waterton and Julesburg, a
distance of about 240 miles. They show the total' return flow, exclusive
of tributary contributions, amounted to about 700 'second-feet in 1891,
nearly 900 in 1900, 1,200 in 1908 and. nearly 1,SaO second-feet in 19'10.
Because of the stabilization of the irrigated area and the more or less
fixed water supply over the last several years, Mr. Houk feels that the
return flow to the South Platte is stabilized at about a maximum of
1,000,000 acre-feet per year.

In 1926 the irrigated area along this stretch of the river was
approximately 1,000,000 acres and on this basis the return was one
acre-foot per acre irrigated. In some areas this ratio is much greater.
For the S.outh Platte the return flow is .estimated to Db about one..third
to one-half the annual diversion from the river.

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By comparison it is interesting to note the extent of return flow
in the Horth Platte Valley between Whalen Dam in Wyoming and Bridgeport,
Nebraska, a distance of ?3 miles. R. A. Willis, former chief of the
Buroau of Irrigation for the State of Nebraska, reports the results of
a return flow study, in Vol. 9lJ., Transactions of the American Society
of Civil Engineers covering the years 1925, 1926, and 1927 for this
stretch of the North Platte River. The mean annual diversion for

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