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I I , I I II I I I I I I ,I I I II I I I I I I I After several decades of work and dollar investments to address flood problems in Delta, the immediate threat to human life has stabilized. Other flood losses (public and private property damage, injuries, disruption and disaster relief) continue to rise, and the natural resources provided by floodplains are still being degraded. Aesthetic and serene river views are a main selling point for many citizens. The main area of concern in Delta is two-fold. I.First, the 100-year floodplain of these two rivers, both up and down stream of their confluence, is a concern. As it happens, some of the community's business district is located in this area. Most of the structures in this area were constructed before the community entered the NFIP. Ifstructural and non-structural mitigation activities can be implemented, it will ultimately reduce flood losses in the community. 2. Second, is the threat from dam failure. In a dam failure event, (Blue Mesa Dam) either from natural causes or from an act of terrorism, the consequences would be far worst. The "Colorado River Storage Project, Blue Mesa Morrow Point and Crystal Dams, Colorado Inundation Map" shows that in a worst case scenario we could see a maximum flow of 4,306,000 cfs with depths at Delta 56 feet above the streambed! This would obviously cause catastrophic damage anywhere along the river as well as inundating the entire Downtown Business District and many of the homes and industries in Delta. B. Flood Hazard Areas Our focus in the plan will be only with area of concern number one (100 floodplain) , in that we see planning for dam failure events as an evacuation and recovery operation and that mitigating flood damage from this event in advance would be difficult. The next step in defining the problem is to clearly identify the areas affected. One should I) review mapping of the flood hazard areas, 2) collect additional flood hazard data, and 3) identify other hazards which affect the area. 1. Planning Maps Flood hazard areas are most often displayed on maps. The latest Flood Insurance Rate Map for Delta was issued by FEMA on August 19, 1991. Copies ofthe map can be used and marked up as part of the planning process to develop the local Pre-Disaster Flood Hazard Mitigation Plan. 1. Unmapped Flooding Flooding may include more than just over-bank flooding from local streams and lakes. We do occasionally have threats from "stormwater" flooding as well as irrigation ditch flooding. The irrigation ditch flooding is the responsibility of the irrigation company or the user of the water. Water users are responsible for their waste water until it gets back into a natural waterway.