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Isolated summer thunderstorms are frequently severe but limited in area extent. Available records for this region indicate that snow melt has not contributed significantly to most of our major creeks. Floods in our watersheds are characterized by high peak flows, moderate volume and short durations. Non-structural or preventive measures involve keeping people and damage-prone property out of the floodway and regulating its use so as to minimize damage when flooding occurs. Use of the flood plains is regulated to reduce damages and prevent changes in the hydraulic character of the stream which will increase flood heights both upstream and downstream. FLOOD CHARACTERISTICS . Regulations for flood loss control must be based upon realistic appraisals of flooding threats.. The flood hazard at a particular site usually cannot be estimated by the average citizen by physical examination of the site. Relevant aspects of the flood hazard are often difficult to identify. Soils, topography, vegetation patterns, and physical evidence that flooding has occurred, but tell little about specific velocities, duration or frequencies. Furthermore, flood frequency may be a statistical tool for analysis and decisions about risk, but it is not a good indicator of how floods behave. As G. R. Phippen stated in his article, "A New Course to Ararat", in the summer of 1971 issue of "Water Spectrum", "The so-called lOO-year flood, for example, is a large flood in the inter- mediate range of possible flooding; and it can occur in any year. Statistically, it has the same 1 per cent chance of being equalled or exceeded in any year--or perhaps more significantly, about a 25 per cent chance in the usual mortgage period." Most of the flood producing storms over the Pikes Peak region occur during the summer months from May through August. During this period, masses of warm, moist air from the Gulf of Mexico and cold, comparatively dry air from the polar regions, combine over the higher land areas to cause increased thunderstorm activity. The severest storms often generate in the transitional periods of late spring and early fall when polar air intrusions are most intensive. The technical procedures for estimating the flooding charac- teristics of a stream are complex and require detailed, sophisticated analysis. El Paso County has engaged the services of the U.S. Soil Conservation Service and the Corps of Engineers to complete detailed flood plain studies of basins such as Monument Creek, Fountain Creek, Sand Creek and Jimmy Camp Creek. As resources and funds become available, additional basins will be studied. - 6 -