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<br />Colorado Dam Failure Hazard
<br />
<br />* DAM OWNERSHIP IN COLORADO
<br />
<br />o Federal, , , , , . , , , , , , , , , , , " 140
<br />
<br />o State "",,,,.,,,,,,,,,.,,83
<br />
<br />o Local GovenunentsIDistrictB, , , , , , 276
<br />
<br />o PrivatelyOwned , , . . , , , , , , " 1,348
<br />TOTAL 1,824
<br />
<br />. (Mom'"",,, ond l_ected by Stole E",iIuJer)
<br />
<br />failure began to develop during the 1980s following
<br />the start of the National Dam Safety Program. Emer-
<br />gency Preparedness Plans (EPP's) outline what to do
<br />and who to call in an emergency, and which people to
<br />evacuate if necessary. Unfortunately, EPP's do not ex-
<br />ist for many dams in Colorado with high and moder-
<br />ate hazard ratings (imminent damage to life and/or
<br />property). State law requires that all Class I (high
<br />hazard) and Class II (moderate hazard) dam owners,
<br />public and private, prepare, update, and exercise
<br />EPP's on an annual basis. The State Engineer's Office
<br />and the Office of Emergency Management reviews
<br />and archives the plans and furnishes guidelines for
<br />their preparation.
<br />
<br />Status of Dams in Colorado
<br />
<br />Of the 27,000 dams that exist in the state, many are
<br />small and pose only minor hazards. About 1,800 are
<br />considered to be significant structures which the State
<br />Engineer regularly monitors and inspects. About 75
<br />percent of these are privately owned, with federal,
<br />state and local governments owning the remaining 25
<br />percent. Many dams in the state are old and struc-
<br />tural conditions vary. Some exist near active faults or
<br />in areas where mild seismic events occur.
<br />
<br />Dam Safety Hazard Awareness
<br />
<br />Hazard awareness is an important component of dam
<br />failure hazard mitigation. Since they are relatively
<br />rare events, disasters tend to be assigned a low prior-
<br />ity by local governments and the general public until
<br />problems develop. Many people who live in the poten-
<br />tial inundation zone of a dam are unaware of the po-
<br />tential hazard or the steps they can take to protect
<br />themselves in the event of a dam failure. As more
<br />
<br />people settle below Colorado's dams and vulnerability
<br />increases, the urgency to deal more directly with
<br />threatened populations becomes especially important.
<br />
<br />Many residents in potential dam failure inun-
<br />datUm _s remain unaware af the threat and
<br />Iww to deal with it,
<br />
<br />In the event of a catastrophic dam failure, residents in
<br />the inundation zone must be aware of the:
<br />
<br />. appropriate warning rignal,
<br />
<br />. short time to evacuate, and
<br />
<br />. safetd evaclUltion route,
<br />
<br />Levels of awareness vary across Colorado from full
<br />awareness of the hazard and emergency measures to
<br />complete ignorance of one's location in an inundation
<br />zone for one of the state's 236 high hazard dams.
<br />Some counties have only one or two high hazard dams
<br />while in other counties a significant portion of the
<br />population lives below high hazard dams (Larimer
<br />County has 45 and the Lawn Lake disaster remains
<br />strongly registered in public perceptions). The town of
<br />South Fork in Rio Grande County is an example of a
<br />town in the inundation zone of several dams located in
<br />Rio Grande, Mineral and Hinsdale Counties. Coun-
<br />ties, cities, towns and smaller unincorporated commu-
<br />nities urgently need:
<br />
<br />. better public awareness of the dam hazard,
<br />particularly who is in danger,
<br />
<br />. plantl for warning and evacuating threatened
<br />segments of the population (Bignals and
<br />evacuation routes),
<br />
<br />. public familiarity with community plans
<br />through well publicized exercises and other
<br />media channels.
<br />
<br />Conclusions & Recommendations
<br />
<br />Structural and nonstructural dam safety programs
<br />are vital to Colorado. In theory, if all necessary struc-
<br />tural measures were implemented, few if any non-
<br />structural steps would be necessary. Since it is
<br />unlikely that perfect dam safety can be obtained
<br />through structural means alone, a variety of nonstruc-
<br />tural means should be employed to lessen the poten-
<br />tial impacts on the many Coloradans who currently
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