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<br />librarian of the State historical society in Denver; _ newspaper
<br />publishers throughout the State, who allowed access to' their files;
<br />and by many residents who furnished data regarding floods in their
<br />localit.ies. Leon R. Sawyer collected most of the flood data, Lawrence
<br />F. Hanks devoted considerable time to field examinations of specific
<br />floods, J. H. Baily made many of the computations, and Robert
<br />Follansbee prepared the report.
<br />
<br />.
<br />
<br />INVESTIGATIONS
<br />
<br />Unusual floods, whether on large or small streams, have attracted
<br />the attention of the Geological Survey for many years, and whenever
<br />possible this bureau has made investigations of them and has pub-
<br />lished reports embodying its findings. Likewise, the State engineer
<br />of Colorado has investigated certain floods; for some of these his
<br />findings have been published, and for others unpublished reports are
<br />on file in his office. A few floods have been investigated by munici-
<br />pal agencies, which have published reports. In the preparation of
<br />this paper, these various reports have been drawn upon for pertinent
<br />facts, credit for which is given in connection with the discussion of
<br />the specifk floods. A list of the reports follows
<br />
<br />HrNDERLIDER, M. C., and assistants, Floods in the Denver district, in Murphy,
<br />E. C., and ethers, Destructive floods in the United States in 1904: U. S.
<br />Geological Survey Water-Supply Paper 147, pp. 150-171, 1905. Includes
<br />the following: Flood on Cache la Poudre River [from reports of J. A. Arm-
<br />strong], pp. 155-156; Purgatory Riyer flood, by R. 1. Meeker, pp. 158-169;
<br />La Plata River flood [from report of Theo Tobish], pp. 169-171.
<br />FREEMAN, W. B., Flood in the Arkansas Valley, Colo., October 1908, in Surface
<br />Water Supply of the United States, Hl07-08, part 7, Lower Mississippi River
<br />Basin: U. S. Geological Survey Water-Supply Paper 247, pp. 33-40, 1910.
<br />FREEMAN, W. B., Flood in San Juan Valley, September 5 and 6, 1909, in Surface
<br />Water Supply o(the United States, 1909, part 9, Colorado River Basin:
<br />U. S. Geological Survey Water-Supply Paper 269, pp. 187-191, 1911.
<br />RUSSELL, G. H., and GRAY, G. A., Flood of October 1911 in the region of the
<br />San Juan, San Miguel, and La Plata Mountains, in Surface Water Supply
<br />of the United States', 1911, part 9, Colorado River Basin: ,U. S. Geological
<br />Survey Water-Supply Paper 309, pp. 246-249, 1914.
<br />FOLLANS:llEE, ROBERT, and JONES, E. E., The Arkansas River Flood of June 3-5,
<br />1921: U. S. Geological Survey Water-Supply Paper 487,44 pp., 1922.. '
<br />FOLLANSBEE, ROBERT, and HODGES,P. V., Some Floods in the Rocky Mountain
<br />'Region, in Contributions to the Hydrology of the, United States, 1923:'-24:'
<br />U. S. Geological Survey Water-Supply, Paper 520, pp, 105-129, 1925. ' In-
<br />cludes, under the heading, "Cloudburst floods," reports On the following
<br />localities:' Templeton Gap near Colorado Springs, Colo., p. 121; Cherry
<br />Creek near Parker, Colo:, pp. ,122-123; Buckhorn Creek near Loveland,
<br />Colo., pp. 123-,124.' " . '
<br />
<br />GEOLOGICAL SURVEY
<br />
<br />'.'
<br />
<br />"
<br />
<br />
<br />'II
<br />
<br />PREVIOUS FLOOD
<br />
<br />1911.
<br />The greatest floods on the plains streams occurred during May and June 1935
<br />and were caused by cloudbmsts. Ranchers living in the vicinity noted rainfalls
<br />as high as 24 inches in a 13-hour period, measurements being made in a stock tank.
<br />,The effect of settlement on channel capacities can be clearly traced. \"hen
<br />settlement began, and with it the bcginning of the livcstock industry, t.he plains
<br />were thickly covered \\-ith a luxuriant. growt.h of grasses. \Vit.h the dcvelopment
<br />of the livestock indust.ry the grass covcr was grazed so closcly that it. afforded
<br />lit.tle protection against erosion during thc violent rains and resulting floods. The
<br />intensive grazing packed tbe soil so hard as t.o incrcase gr2atly the pcrcentage of
<br />rainfall that entered the streams. This condition was notcd during the Arkansas
<br />River flood of October 19os. when an estimated tW::l-thirds of the 6-inch rainfall
<br />appeared almost immcdiately in the ncarby st.reams.
<br />The development of flood protection was of slow growth and progressed through
<br />four stages: (1) Remo\'al of buildings to higher ground; (2) improvemcnt of river
<br />channel capacity but without. definite objective, owing to lack of knowledge of
<br />flood flows to be accommodated; (3) increase of channel capacity to equal meas-
<br />ured peak flow of recent outstanding floods; and (4) construction of storage or
<br />detention rcservoirs to hold hack the greatest probable flood. These stages suc-
<br />ceeded each other as losses from flood became greater and as thc accumulation of
<br />meteorologic and hydrologic data permitted a more rat.ional solution of thc flood
<br />problem.
<br />INTRODUCTION
<br />
<br />River, June 1921; Rio
<br />San .Juan Rivcr, Oct.ober
<br />
<br />. I'
<br />larger streams occurred as follows: South Platte
<br />Grande, June 19 ,; Colorado River, June and July 1884;
<br />
<br />In July 1938 the Federal Emergency Administration of Public
<br />'\Vorks made an allotmmt to the I Geological Survey, United States
<br />Department. of the Interior, for flood and drought studies. ' In Colo-
<br />rado the studies were devoted to a compilation of all available data
<br />regarding past floods. Not only were the newspaper files searched and
<br />all pertinent records obtained from the State engineer and other public
<br />officials, but all available writings of early travelers through Colorado
<br />before permanent settlement took place, including those ofthe Spanish
<br />explorers and padres, were examined. Information regarding some
<br />later floods was obtained through field studies. As a necessary part
<br />oi flood study, meteorological data, so iar as available, were compiled
<br />for the major floods' ,
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<br />I
<br />l
<br />
<br />ACKNOWLEDGMENTS
<br />
<br />The United States Weather Bureau furnished data on storms in
<br />Colorado. Search was made in the National Archives for material
<br />regarding storms in early years. The Bureau of Reclamation furnished
<br />, 'I.. _ _ . ,. ____ .11 r"l_ . c ~ :"T'Ii". ,-
<br />newspaper cnpplllgs lroID tile UUIlIllson rress n.eVlew regarumg snow-
<br />fall and high water during the spring of 1884 and a report on the Wilson
<br />Creek flood. L. T. 8m-gess" chief hydrographer in the office of the
<br />State engineer of Colorado, furnished all, available flood records.
<br />Acknowledgment of specific information is made at appropriate places
<br />in the ,report.' , Valuable assistan~ewas given by Mrs,;,Mildred Rex,
<br />
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