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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />rlate 5 graphically depicts extreme and mean annual runolT. Using plotted daily flow <br /> <br />values from historic records at the Dolores River at Dolores gage, it compares examples of the <br /> <br />extremes for wet and dry \vatcr years and an example of an average water year (Appendix A, <br /> <br />Table 1). The runolT for water year 1941 was one of greatest ever recorded at the Dolores gage; <br /> <br />the statistics include maximum 1 ~day flow 6,550 cfs and annual volume 521,726 ac-fi. (See <br /> <br />Appendix A, Table I for runofT and maximum I-Jay flows for the Delores River al Dolores <br /> <br />gage.) By comparison, the driest year recorded at the Dolores gage was water year 1977; the <br /> <br />maximum I-day flow was 385 cfs and annual volume 63,000 ac-tl. Based on the 92-ycar record <br /> <br />at Dolores River at Dolores gage. the average daily flow is 430 cfs and the average annual volume <br /> <br />312,000 ac-fl. Water year 1969 is an example of an average water year with an average daily <br /> <br />flow of 430 ers and annual volume of 312,000 ac-fl. <br /> <br />5.7 Flood History. The flood of greatest magnitude in the Dolores River Basin occurred on <br /> <br />5 October 1911, when a general stoml with a few periods of cloudburst intensity followed a <br /> <br />summer of above-average rainfall. This stonn caused flooding on the Animas, San Juan. and <br /> <br />Colorado rivers and their tributaries. demolishing bridges. railroad structures, homes, and <br /> <br />buildings in Colorado, New Mexico, Arizona. and Utah. In the Dolores area. the greatest damage <br /> <br />was to the Rio Grande Southern Railroad; much of its track was entirely destroyed. Ranchers <br /> <br />also sustained severe losscs. The flood reached a stage of 10.2 feet on the gage at Dolores wilh an <br /> <br />estimated peak discharge of about 10,000 cfs. It caused the river to break through the railroad <br /> <br />grade and flow down an old river channel, inundating a part of Dolores to a depth of I to 3 feet <br /> <br />and washing out one span of the Fourth Street Bridge. <br /> <br />The flood of 19 June 1949 is classified as a rain-an-snow type cvent. It produced the <br /> <br />second largest peak flow at the Dolores River near Dolores gage, 8,140 efs. In addition to the <br /> <br />14 <br />