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<br />Learn-Assess <br /> <br />minutes or a few hours, leaving little or no time for <br />evacuation. The massive volume of water and its <br />high velocity will cause severe damage. <br /> <br />More than 20 federal agencies and four <br />independent offices and commi $i ms (Wl about <br />4,000 dams, have regulatory authority over 6,000 <br />others, and have various other responsibilities for <br />additional tens of thousands of nonfederal dams. <br />The number of dams of all types and sizes in the <br />United States is unknown, but when small dams <br />(such as for farm ponds) are included, the total <br />could be as high as several million. <br /> <br />State regulation of dams is generally considered to <br />have started in California after the failure of the St. <br />Francis Dam in 1928. The California law has been <br />strengthened at least twice since then after other <br />major dam failures or near failures, and has been <br />used as model state legislation for the review, <br />inspection, certification, and maintenance of <br />nonfederal dams. As of 1989,31 states had <br />statutory authority to perform all of these <br />functions, and only two had no statutory authority <br />at all. The states had a collective 1989 budget for <br />dam safety of $17,668,552. The Association of <br />State Dam Safety Officials, which was organized <br />in 1984, has become a major influence in <br />improving state regulation of dams. <br /> <br />Home Leamin2 Center Back <br /> <br />Dikes, Levees, and Floodwalls <br /> <br />Dikes, including levees and floodwalls, can be <br />thought of as dams built roughly parallel to a <br />stream rather than across its channel, or parallel to <br />the shorelines oflakes, oceans, and other water <br />bodies. Levees are generally constructed of earth, <br />floodwalls of masonry or steel. Levees were <br />probably the first structures built for flood control <br />by European immigrants to North America. The <br />first levee in the Mississippi Valley was <br /> <br />Page 13 of36 <br />