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3 BACKGROUND ON DAMS <br />As a precursor to the technical analysis in this report, it is important to understand some basic <br />functions of the Colorado Dam Safety Program. Ensuring the safety of dams in Colorado is <br />performed and administrated under the Division of Water Resources, Office of the State Engineer, <br />through the Dam Safety Branch. All dams in Colorado are regulated and subject to the authority <br />of the State Engineer consistent with Title 37, Article 87 of the Colorado Revised Statues (C.R.S.) <br />In addition to C.R.S. requirements, the Dam Safety Branch administers dams in accordance with <br />the "Rules and Regulations for Dam Safety and Dam Construction" (hereafter, the Rules). The <br />purpose of the Rules is to provide for public safety through establishment and administration of <br />standards and to create a public record for reviewing the performance of dams. <br />There is hazard potential or risk associated with storing water behind dams for beneficial uses due <br />to the fact that unintended release of those stored waters has consequences. This risk is tolerated <br />due to the beneficial uses that the stored water provides. The consequences vary, in part, due to <br />the size of the dam and volume of water stored, but also to the extent of development below the <br />dam. Dams in Colorado are categorized in groups by hazard classification, which is defined by the <br />consequences or damage caused by their sudden failure. All Colorado dams are assigned to one of <br />four hazard classifications; <br />• A High hazard Dam is a dam for which loss of human life is expected to result from failure <br />of the dam. <br />• A Significant hazard dam is a dam for which significant damage is expected to occur, but no <br />loss of human life is expected from failure of the dam. Significant damage is designated as <br />damage to structures where people generally live, work, or recreate, or public or private <br />facilities. Significant damage is determined to be damage sufficient to render structures or <br />facilities uninhabitable or inoperable. <br />• A Low hazard dam is a dam for which loss of human life is not expected, and significant <br />damage to structures and public facilities as designed for Significant hazard dam is not <br />expected to result from failure of the dam. <br />• A No Public Hazard dam is a dam for which no loss of human life is expected, and which <br />damage only to the dam owner's property will result from failure of the dam. <br />In addition to hazard classification, dams are also defined by their size. Dams are divided into two <br />major size categories; jurisdictional and non - jurisdictional. Non - jurisdictional (NJ) dams are <br />defined as having a capacity of 100 acre -feet or less, creating a reservoir with a surface area 20 <br />acres or less at the high -water line, or being 10 feet in height or less. Dams and reservoirs <br />exceeding any one of these criteria are considered jurisdictional. Additional definitions of "a dam" <br />are contained in Rule 4.2.5 of the Rules. <br />The hazard classification and size categories of dams dictate the requirements of their regulation. <br />Larger dams, with higher consequences of failure are subject to more strict regulation. For <br />example, large, High hazard dams are inspected every year and have the most stringent <br />Report of the September 2013 Little Thompson River Flooding COLORADO <br />and Big Elk Meadows Dam Failures, June 2014 (Revised, Dec 2014) A&V Division of Water Resources <br />Page 3 of 48 <br />DAM SAFETY BRANCH <br />