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<br /> <br />. <br /> <br />* Apparently low (based on limited available data) <br /> <br />-~ <br /> <br />I <br />:. <br />I <br />III <br /> <br />EXPLANATION <br />HIGH l1li LOW (?)* <br /> <br />MEDIUM 0 LOW <br /> <br />WY : <br />-(:0'-------- -: <br />I <br />; <br />I <br />, NB <br />)i ------ <br />-- KA <br />. <br />I <br />I <br />. <br />, <br />I <br />1 <br />I <br />I <br /> <br />Figure 1. Generalized map showing the relative potential for landsliding in Colorado and surrounding <br />states (Wiggins and others. 1978). <br /> <br />Large landslides may impact dam abutments, block <br />spillways, or lead to overtopping and erosion of a dam or <br />spillway, ultimately leading to dam failure. Since Colo- <br />rado has 586 "high" and "moderate" hazard dams <br />(defined according to the anticipated number of lives lost <br />and damage caused if the dam failed), the possibility <br />that landslides can contribute to dam failure is very real. <br /> <br />The Need for Planning <br /> <br />Landsliding occurs in every state in the nation, <br />producing significant impacts on the economies of more <br />than half the states (Committee on Ground Failure <br />Hazards, 1985). While landslides can and do occur as <br />specific local events, as much as one-third of the <br />nation's annual landslide loss is associated with major <br />statewide or regional landslide disasters resulting from <br />heavy rains or snowmelt. <br /> <br />8 <br /> <br />Landsliding of this sort often extends beyond the boun. <br />daries of any single state or local governmental entity. <br />Because of tlUs, and because effective measures for reduc* <br />ing landslide losses require the cooperation of federal, <br />state, local. and private entities. reduction of landslide <br />losses should be viewed as a national goal requiring national <br />leadership <br />(Conumltee on Ground Failure Hazards, 1985, p. 1). <br />Olshansky and Rogers (1987, p. 941) emphasize the <br />seriousness of the situation: <br />Public policies for reducing landslide hazards and compen- <br />sating landslide victims are at best piecemeal and poorly <br />coordinated; at worst, they are misguided, unenforced, or <br />nonexistent. Neither legislatures nor the courts have taken <br />a comprehensive approach toward solving this problem. <br />In Colorado and in the United States as a whole, the <br />need to mitigate the dangers and costs of landsliding is <br />clear. Lessening the impact of these costly events can <br />save many lives and enormous amounts in property <br />values. Successful and cost-effective national landslide <br />