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<br />over the high plains gradually decreased from west to east and varied from 5 inches at <br />Boulder to approximately 2.5 inches at the mouth. The mountain rainfall combined wnh <br />the snowmelt runoff to produce the greatest flood known at Boulder, which came roaring <br />down the valley during the night of 30 May 1894. Buildings, bridges and even long <br />sections of roads and railroads were washed away. Damage was exceptionally heavy <br />along Fourmile Greek and in Boulder. Computations made 18 years later by Metcalt and <br />Eddy produced Etstimates of the peak discharge in Boulder that ranged from 9,000 cubic <br />feet per second '10 13,600 cubic feet per second. <br /> <br />. <br /> <br />Flood of 1-2 June 1914. This flood was caused by rainfall on 1 June of more than 1 <br />inch on North Be,ulder Creek near Silver Lake at an elevation of 10,200 feet. The flood, <br />described as the worst since 1894, washed out numerous bridges between Colburn Mill <br />and Boulder Fallis. Several hundred feet of main line for Boulder's water system were <br />destroyed. The peak discharge in Boulder was estimated at 5,000 cubic feet per second. <br /> <br />~ <br /> <br />Flood of 2-7 .June 1921. Lillie is known of this flood except that n produced the highest <br />peak discharge ever rBCOrded at the Oradell gage. A discharge of 2,500 c.f.s. was <br />recorded on 6 Junec Rainfall totaled 3.36 inches at Boulder through a period of 2-7 June. <br /> <br />Flood of 3-10 June 1923. This storm centered over the high plains east of the <br />mountains. Rainfall at Boulder totaled 3.84 inches through a period of 3-1 0 June wnh 2.39 <br />inches of the total precipnation falling on 9 June. Combined flows from Boulder, South <br />Boulder, and Bear Canyon Creeks produced flooding downstream of Valmont. <br /> <br />Flood of 4 SEtotember 1938. A large storm produced general rains over all of Eastem <br />Coloradoc The largest amounts of precipitation occurred in the mountains where over 6 <br />inches was reported west of Eldorado Springs. Boulder reported 3c62 inches of <br />precipitation from 31 August to 4 September with 2c32 inches falling on 2 September. <br />Eldorado Springs, located in the South Boulder Creek basin, had 4.42 inches of rainfall. <br />Approximately 80 percent of the total precipnation falling in the South Boulder Creek basin <br />fell in the late afternoon and evening of 2 September. The resulting flood on South <br />Boulder Creek had an estimated peak discharge of 7,390 c.f.s. at the Eldorado Springs <br />gaging station. The peak gradually subsided as the flood moved downstream. maximum <br />discharge of 4,410 c.f .s. occurred near the mouth of Boulder Creek at noon on 3 <br />September. Several buildings in Eldorado Springs were destroyed as a result of erosion <br />around their foundations. Numerous bridges were destroyed and the South Boulder Creek <br />valley from Eldorado Springs to Boulder Creek and down Boulder Creek to the St. Vrain <br />Creek was described by local newspapers as being in shambles. This flood is the highest <br />recorded flood on the South Boulder Creek. <br /> <br />Flood of 6-8 Mav 1969. This flood was also the result of long duration rainfall. <br />Precipnation wasc heaviest in the mountains, part of which fell as snow. In the Boulder and <br />South Boulder Creek basins the rainfall continued at a moderate rate for nearly 4 days. <br />Total precipnation for the storm amounted to 7.60 inches at Boulder and 9.34 inches at the <br />Boulder Hydroelectric Plant located about 3 miles up the canyon from Boulder. <br />Precipnation amounts totaled 8.11 inches at Eldorado Springs and 10.05 inches at Gross <br />Reservoir on South Boulder Creek. Peak flooding occurred on the 7th of May on both <br /> <br />" <br /> <br />. <br /> <br />Colorado Flood <br />Hydrology Manual' <br /> <br />4.12 <br /> <br />fPI1FT <br />