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<br />for the Wild Horse Creek 100-year flood plus concident flow in the Arkansas River was not <br />prepared because it has a less critical backwater elevation east of the Town of Holly. <br /> <br />Because of the protection provided by the Project, the pre-project 100-year floodplains for <br />Wild Horse Creek and the Arkansas River have been modified. The I DO-year flood is now <br />excluded from the corporate limits of the Town of Holly as shown on Figure ] 3. The <br />unincorporated areas to the landside of the Project levee are also protected to the the boundary <br />of the 100-year flood backwater at approximate ground elevation 3384.8 feet (MSL) east of <br />Holly. <br /> <br />The flood boundary elevation 3384.8 feet (MSL) is for the I DO-year flood only. Larger <br />floods have a higher elevation which would cause the floodplain boundary from the backwater <br />to be further west. Also it must be noted that floods larger than the I DO-year flood can occur <br />on both Wild Horse Creek and the Arkansas River and the Town may be subject to risks from <br />such floods. Floods were experienced in the summer of 1993 throughout the Midwest that in fact <br />exceeded the design capacity of their levees. <br /> <br />The modification ofthe pre-project I DO-year floodplains by the Project levee confines the <br />I DO-year flood to a smaller portion of the original floodplain. This reduction of the area <br />available for flow increases the depth of flow on the riverside of the levee (west and south). The <br />increase in depth of flow on the riverside for the IOO-year flood varies from 0.1 feet to 3.5 feet <br />as shown on Table 2. <br /> <br />The I DO-year floodplain designations madc' prior to the construction of the Project remain <br />in effect for the unincorporated Prowers County areas west and south of the levee and east of the <br />backwater floodplain boundary at elevation 3384.8 fe(:t (MSL) as previously described. <br /> <br />The two interior ponding areas used to pond interior drainage runoff until th,: Wild Horse <br />Creek and Arkansas River flooding recedes are outside the corporate limits of the Town and have <br />relatively low valued agricultural use. Damag(:s are low and limited mainly to temporary <br />inconvenience and nuisance. These interior ponding areas can easily handle the I DO-year interior <br />storm volume since they were designed for the Corps' Standard Project Flood interior storm <br />volume which is larger than the 100-year interior storm volume. <br /> <br />A I DO-year flood profile is not required for the ponding areas due to a level water surface <br />in the ponding area during a 100-year flood event. The original design (March 1977) of the <br />borrow area which formed the smaller ponding area to tile north showed a 100-year water surface <br />elevation of 3411.2 feet (MSL). Subsequent revisions in December 1979 and March 1980 of this <br />borrow area enlarged it somewhat. These enlargements would not increase the 100-year water <br />surface elevation. The original design (March 1977) of the borrow area which formed the larger <br />ponding area to the south showed a IOO-year water surface elevation of 3384.7 feet (MSL). <br />Subsequent revisions in August 1980 significantly enlarged this borrow area which would not <br />increase the 1 DO-year water surface elevation. <br /> <br />II <br />