FLOOD00898

• County: Statewide
• Title: Floods in Colorado
• Date: 6/1/1948
• Prepared For: State of Colorado
• Prepared By: USGS
• Floodplain - Doc Type: Flood Documentation Report

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. FLOODS IN COLORADO

larger streams and oeourred as follows: South Pla.tte River, June 1921; Rio
Grande, June 1927; Colorado River, June and July 1884; San Juan River, October
1911. '
The greatest floods on the pIaine streams occurred during May and June 1935
and were cswred by cloudbursts. Ranchers living in the vicinity noted rainfalls
as high as 24 inches in a 13-hour period, measurements being made in a stock te.nk.
The effect of settlement on channel capacities can be clearly traced. When
settlement began, and with it the beginning of the livestock industry, the plains
were thickly covered with a luxuriant growth of grasses. With the development
of the livestock industry the grass cover was grazed so closely that it afforded
little protection against erosion during the violent rains and resulting floods. The
intensive grazing packed the soil so hard as to increase graatly the percentage of
rainfall that entered the streams. This condition was noted during the Arkansas
lUver flood of October 1908, when an estimated two-thirds of the 6~inch rainfall
a.ppeared almost immediately in the nearby streams.
The development of flood protection was of slow growth and progressed through .
four stages: (1) Removal of buildings to higher ground; (2) improvement of river
channel capacity but without definite objective, owing to lack of knowledge of
flood flows to be accommodated; (3) increase of channel capacity to equal meas-
ured peak flow of recent outstanding floods; and (4) corustruction of storage or
detention reservoirs to hold back the greatest probable flood. These stages suc-
ceeded each othar as losses from flood became greater and as the accumulation of
meteorologic and hydrologic data permitted a more rational solution of the flood
problem.

INTRODUCTION

In July 1938 the Federal Emergency Administration of Public
Works made an allotm~nt to the Geological Survcy, United States
Department of the Interior, for flood and drought studies. In Colo-
rado the studies were devoted to a compilation of all available data
regarding past floods. Not only were the newspaper files searched and
all pertinent records obtained from the State engineer and other public
officials, but all available writings of early travelers through Colorado
before permanent settlement took place, including those oftheSpanish
explorers and padres, were examined, Information regarding some
later floods was obtained through field studies. As a necessary part
of flood study, meteorological data, so far as available, were compiled
for the major floods.

ACKNOWLEDGMENTS

The United States Weather Bureau furnished data on storms in
Colorado. Search was made in the National Archives for material
regarding s.torms in early years. The Bureau of Reclamation furnished
newspaper clippings from the Gunnison Press Review regarding snow-
fall and high water during the spring of 1884 and a rcport on the Wilson
Creek flood. L. T. Burgess, chief hydrographer in the office of the
State engineer of Colorado furnished all available flood records.
Acknowledgment of specific information is made at appropriate places
a U_L_1...1~ ........~:.....n.........n ~TOIQ D'lVAn hv Mrs. Mildred Rex,

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PREVIOUS FLOOD INVESTIGATIOlilB

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librarian of the State historical society in Denver; by newspaper
publishers throughout the State, who allowed acceBB to their files;
and by many residents who furnished data regarding floods in their
localities. Leon R. Sawyer collected most of the flood data, Lawrence
F. Hanks devoted considerable time to field' examinations of specific
floods, J. H, Baily made many of the computations, and Robert
Follansbee prepared the report. .

. PREVIOUS FLOOD INVESTIGATIONS

Unusual floods, whether on large or small streams, have attracted
the attention of the Geological Survey for many years, and whenever
possible this bureau has made investigations of them and hs.s pub-
lisbed reports embodying its findings. Likewise, the State engineer
of Colorado has investigated certain floods; for some of these his
findings have been published, and for oth~rs unpublished reports are
on file in his office. A few floods have been investigated by munici-
pal agencies, which have published reports. In the preparation of
this paper, these various reports have been drawn upon for pertinent
facts, credit for which is given in connection with the discussion of
the specifir. floods. A list of the reports follows:

GEOLOGICAL SURVEY

HINDERLIDER, M. C., a.nd assistants, Floods in the Denver district, in Murphy,
E. C., and others, Destructive floods in the United States in 1904: U. 8.
Geological Survey Water~Supply Paper 147, pp. 150-171, 1905. Includes
the following: Flood on Cache la Poudre River [from reports of J. A. Arm-
strong}. pp. 165-156; Purgatory River flood, by R. 1. Meeker, pp. 158-169;
La. Plata. River flood [from report of Thea Tobishl, pp. 169-171.
FREEMAN, W. B., Flood in the Arkansas Valley, Colo., October 1908, in Surface
Water Supply of the United States, 1907-08, part 7, Lower Mississippi River
Basin: U. S. Geological Survey Water-Supply Paper 247, pp. 33-40, 1910.
FREEMAN, W. B., Flood in San Juan Valley, September 5 and 6, 1909, in Surface
Water Supply of the United States, 1909, part 9, Colorado River Basin:
U. S. Geological Survey Water-Supply Paper 269, pp. 187-191, 1911.
RUBSELL, G. II., and GRAY, G. A., Flood of October 1911 in the region of the
San Juan, San Miguel, and La Plata Mountains, in Surface Water Supply
of the United States. 1911, part 9, Colorado River Basin: U. S. Geological
Survey Water-Supply Paper 309, pp. 246-249, 1914.
FOLLANSBEE, ROBERT, and JONES, E. E., The Arkansas River Flood of June 3-5,
1921: U. S. Geological Survey Water-Supply Paper 487,44 pp., 1922,
FOLLANSBEE, ROBERT, and HODGl~S, P. V., Some Floods in the Rocky MQuntain
Region, in Contributions to the Hydrology of the United States, 1923-24:
U. S. Geological Survey Water-Supply Paper 520, pp. 105-t29, 1925. In-
cludes, under the heading IICloudburst floods," reports on the following
localities: Templeton Ga.p near Colorado Springs, Colo., p. 121; Cherry
Creek nea.r Parker, Colo., pp. 122-123; Buckhorn Creek near Loveland,
Colo., pp. 123-124.