Laserfiche WebLink
<br />.. <br /> <br />Less than two years later, in March 1955, an ice jam in the White <br />River caused the river to leave its banks; and, at one time, the <br />town water supply was cut off when 6 feet of floodwater covered the <br />water filtration plant. <br /> <br />.. <br /> <br />Water supply was again interrupted by ice jams above and below the <br />town in February 1962. The most recent flood in the area occurred <br />in March 1966, when another ice jam diverted the flow of the White <br />River and several ranches experienced flooding. Local residents l <br />agree that damaging floods occur on the average of once every 7 to <br />10 years, with the majority resulting from ice jams. Shallow flooding, <br />wi th water characteristically less .than 3 feet deep, occasionally <br />occurs in some southern portions of Rangely as a result of rampant <br />thunderstorm runoff from ravines and washes. <br /> <br />. <br /> <br />Due to lack of streamflow records for the immediate vicinity of <br />Rangely, data basic to estimating the frequency of past floods are <br />not available. On the basis of studies made for this report, the <br />March 1955 and February 1962 floods had frequencies approaching 100 <br />years. <br /> <br />2.4 Flood Protection Measures <br /> <br />There are no Federal flood control projects affording protection to <br />Rangely, and none are under consideration. Most new development in <br />Rangely is being kept out of potential flood damage areas. A small <br />levee constructed along the town side of Dragon Wash is capable of <br />protecting a large portion of the town from floods with frequencies <br />approaching 50 years. However, two culverts at street crossings <br />limit the carrying capacity of the 'vash to about a 10-year event. <br />The community is aware of its flood problems and is flood plain <br />management oriented. <br /> <br />3.0 ENGINEERING METHODS <br /> <br />For flooding sources studied in detail in the community, standard hydro- <br />logic and hydraulic study methods were used to determine the flood <br />hazard data required for this study. Floods having recurrence intervals <br />of 10, 50, 100, and 500 years have been selected as having special sig- <br />nificance for flood plain management and for flood insurance prerrrium <br />rates. The analyses reported here reflect current conditions in the <br />watersheds of the s.treams. <br /> <br />3.1 Hydrologic Analyses <br /> <br />Hydrologic analyses were carried oui: to establish the peak discharge- <br />frequency relationships for floods of the selected recurrence <br />intervals for each stream studied in detail in the community. Flow <br />data on the White River were based on the following stream gages: <br /> <br />7 <br /> <br />-~'- <br />