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<br />attenuate in its passage down the Fall River and through the town of Estes
<br />Park.
<br />
<br />After Cascade lake dam failed, two campers were swept to their deaths a
<br />short distance downstream from the dam. The flood continued down the Fall
<br />Ri ver, caus i ng extens i ve damage to homes, mote 1 s, bus i nesses, and bri dges ,
<br />particularly in the town of Estes Park, In Estes Park, the flood entered the
<br />Big Thompson River for a short distance before entering lake Estes, which is
<br />formed by the U.S, Bureau of Reclamation's Olympus dam. This reservoir
<br />contai ned all the fl oodwaters. The peak di scharge was 5,500 fV / s enteri ng
<br />lake Estes, which is about 12,5 mi downstream from lawn lake. Peak discharge
<br />into lake Estes occurred approxi mate ly 3 hours and 40 mi nutes after the
<br />failure of lawn lake dam, In that brief time, three people were killed and
<br />approximately $31 million in private and public damages, cleanup, and economic
<br />loss was reported, The flood resulted in a Presidential Disaster Declaration
<br />for larimer County on July 22, 1982.
<br />
<br />The purpose of this report is to present the setting, a summary of causes
<br />of the dam fai lures, and the hydrologic data on the flood, and to document
<br />geomorphi c effects of the flood, A secondary purpose is to present data
<br />obtai ned from us i ng a dam-break computer model to eva 1 uate that mode I' s
<br />capabilities on high-gradient streams, to enhance and provide supplemental
<br />hydrologic information, and to evaluate various hypothetical scenarios of
<br />dam-breach development and probable impact of the failure of Cascade lake dam,
<br />Documentation and analysis of the flood should provide valuable information on
<br />dam-breach floods of small dams on high-gradient streams for future hazard
<br />mitigation related to dam failures,
<br />
<br />Acknowledgments
<br />
<br />Data and data interpretation in this report are based on the combined
<br />efforts of many private individuals, and upon local county, Federal, and State
<br />agencies. This assistance is gratefully acknowledged.
<br />
<br />Many individuals provided valuable eyewitness information that helped in
<br />the understanding of the flood characteristics. local residents also granted
<br />access to their property to the field personnel working in the flooded area,
<br />Appreciation also is extended to the officials of the town of Estes Park, of
<br />lari mer County, and to Nat i ona 1 Park Servi ce personne 1 who cooperated and
<br />contributed data during the data-collection period.
<br />
<br />Jack Truby, Colorado Division of Disaster Emergency Services, provided
<br />est i mates of fl ood damages, Alan Pearson, Co 1 orado Department of Natura 1
<br />Resources, Division of Water Resources, Office of the State Engineer, provided
<br />i nformat i on on the hi story and causes of fail ures of the dams, Wi 11 i am
<br />Stanton, Colorado Department of Natural Resources, Colorado Water Conservation
<br />Board provided historical flood data, flooded area maps, and additional damage
<br />data.
<br />
<br />The u.S. Bureau of Reclamation, through the Western Area Power Adminis-
<br />tration, provided hel icopter transportation for the collection of data at
<br />
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