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Colorado Springs and extending from the Rocky Mountains down into the plains near Limon, Colorado. Past floods of the mountain tributaries have resulted from snowmelt. Intensive rainstorms cause flooding in both the mountain tributaries and the eastern tributaries. In 1912, Cherry Creek swelled to flood stage from cloudbursts centered simultaneously over Denver and the upper reaches of the creek. In 1933, similar circumstances caused the Castlewood Dam above Franktown in Douglas County to fail, sending a 34,000-cfs flow of water thundering down the canyon into Denver. In 1965, the whole South Platte River Basin was drenched by a unique combination of orographic effects and meteorological conditions that caused the worst flooding in the region's recorded history. Severe thunderstorms had formed over the headwaters of Plum and Cherry Creeks on June 16 and slowly moved northeasterly down the creeks; thus, the heavy rains tended to follow and augment the peak flows. More than 14 inches of rain fell near Monument Divide at Palmer Lake in 4 hours. Overnight, westerly winds shifted the storm front to an orientation over the Kiowa and Bijou Creek basins to meet with thunderstorms forming just south of Agate, where 5.25 inches fell in 45 minutes. The net result was six persons drowned, two other deaths caused by flood-related activities, and estimated damages in the Denver area were $500 million. Flood problems in the area have been the result of not only rare storm events but also of improper floodplain development. Visual accounts of floods have noted that the debris transported by floodwater contained natural debris, such as trees, rock, and soil, but consisted chiefly of i terns foreign to the floodplain, such as houses, bridges, automobiles, heavy equipment, lumber, house trailers, butane storage tanks, and other flotsam. With these items obstructing bridges and culverts, flood levels rose and caused more extensive damage. Property which was not structurally damaged by flood depths and velocities experienced much damage and cleanup cost resulting from mud and silt deposition and erosion. Scenes and 3. Denver of past flooding in Arapahoe County are shown in Figures 2 The pictures were taken from photographic records of the Post and the Arapahoe County Planning Department. 2.4 Flood Protection Measures The first tangible contribution to flood control on the streams flowing through Arapahoe County was made in 1890, when Castlewood Dam, primarily intended for irrigation storage, 'Was completed by the Denver Land and Water Company on Cherry Creek, 35 miles upstream from Denver. The dam, with a storage capacity of 4 billion gallons, was mistakenly regarded by many as protection against deluges. In August 1933, the dam burst under pressure of water from severe thunderstorms in the upper Cherry Creek basin. Flood-control measures were taken on Cherry Creek in 1936 with the B