FLOOD10395 ‎(2)‎

• County: Montezuma
• Community: Dolores
• Stream Name: Dolores River
• Title: Dolores River near Dolores, Colorado, Flood Insurance Study
• Date: 5/1/2004
• Prepared For: Dolores
• Prepared By: US Army Corps of Engineers
• Floodplain - Doc Type: Floodplain Report/Masterplan

Plate 5 graphically depicts extreme and m;:an annual runoff. Using plotted daily flow

values from historic records at the Dolores River at Dolores gage, it compares examples of the

extremes for wet and dry water years and an example of an average water year (Appendix A,

Table 1). The runoff for water year 1941 was one of greatest ever recorded at the Dolores gage;

the statistics include maximum I-day flow 6,550 efs and annual volume 521,726 ac-ft. (See

Appendix A, Table 1 for runoff and maximum I-day flows for the Delores River at Dolores

gage.) By comparison, the driest year recorded at the Dolores gage was water year 1977; the

maximum I-day flow was 385 cfs and annual volume 63,000 ac-ft. Based on the 92-year record

at Dolores River at Dolores gage, the average daily flow is 430 cfs and the average annual volume

312,000 ac-ft. Water year 1969 is an example of an average water year with an average daily

flow of 430 cfs and annual volume of 312,000 ac-ft.

5.7 Flood History. The flood of greatest magnitude in the Dolores River Basin occurred on

5 October 1911, when a general storm with a few periods of cloudburst intensity followed a

summer of above-average rainfall. This storm caused flooding on the Animas, San Juan, and

Colorado rivers and their tributaries, demolishing bridges, railroad structures, homes, and

buildings in Colorado, New Mexico, Arizona, and Utah. In the Dolores area, the greatest damage

was to the Rio Grande Southern Railroad;, much of its track was entirely destroyed. Ranchers

also sustained severe losses. The flood reached a stage of 10.2 feet on the gage at Dolores with an

estimated peak discharge of about 10,000 cfs. It caused the river to break through the railroad

grade and flow down an old river channel, inundating a part of Dolores to a depth of 1 to 3 feet

and washing out one span ofthe Fourth Street Bridge.

The flood of 19 June 1949 is classified as a rain-on-snow type event. It produced the

second largest peak flow at the Dolores River near Dolores gage, 8,140 cfs. In addition to the

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