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. These floods are just a few that have occurred in the area. Major, area-wide floods also occurred in 1904, 1909, 1914, 1921, and 1923. During May 1973, flooding caused an estimated $70,000 worth of damage. No estimates of the recurrence intervals of the historic floods have been made. There has been little documentation of flooding on Wonderland, Elmers Twomile, and Skunk Creeks. > There is a history of debris blockage and flow diversions throughout Boulder. Floods in the Town of Jamestown study area usually occur during the period of May through September. Mountain snowmelt in May and June contributes significant runoff, but serious flooding does not occur unless rainfall accompanies the snowmelt. Peak flooding will usually occur wi thin a few hours after a single rainfall event. Flooding is generally of short duration, but may be prolonged significantly by snowmelt runoff. The steep stream slopes create swift currents during a flood, which produce added damages. Debris carried by the fast-moving water not only threatens bridges and culverts, but batters houses and other structures on the floodplain. The bridge and culvert crossings often result in channel restriction, raising the water-surface elevation. Erosion undercuts and destroys structures which would otherwise receive little damage from inundation. Large quantities of rock are often deposited in portions of the channel, leaving little capacity for future floods. In June l894, a flood roared down James Creek and washed away much of the low-lying area of the town. The flood was caused by heavy rains accompanied by heavy spring runoff. Most of the houses on the north side of Main Street were ruined or washed away, as was much of the road. A similar flood occurred in August 19l3, damaging or destroying almost every house along James Creek. All wagon and footbridges were destroyed, and it took two weeks to open the road to traffic. In August 1955, minutes, damaged several inches of a brief cloudburst, lasting approximately 30 four bridge and culvert crossings and deposited mud in local residences. The town was also flooded in 1965, and again in May 1969, following three days of heavy snow and rain. The floodwaters left the normal channel, destroying a number of buildings and the town water supply. (See Figures 5, 6, 7, and 8 for photographs of the 1969 flood. ) , Readings by members of the University Institute of Arctic and Alpine Research showed snow content or rainfalls of 6.56 inches at 10,000 feet, 9.10 inches at 8,500 feet, and 8.90 inches at 7,200 feet (Reference 18). Flood damage estimates in a 9-county area were $7,000,000, including $700,000 to roads and bridges in Boulder County alone. 17