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San Marcos Floodplain Management Plan: A Sustainable Future for Floodplain Management Application for Flood Protection Study Grant SECTION 2 - PLANNING INFORMATION 15. Describe the geographical planning area (specify river basins, counties, cities, districts, ete. and provide explanation for selecting planning boundaries). The planning area will include the Blanco River watershed, the Willow Springs Creek watershed, the Purgatory Creek: watershed, the Cottonwood Creek watershed, the Bypass Creek watershed, the Sessom Creek tributary of the San Marcos River, and the Schulle Canyon tributary of Sink Creek. These watersheds lie mostly within the corporate jurisdiction of the City of San Marcos and its ETJ, but also within some areas of Hays County. The study reaches were selected based on kno~ recurring problem areas and areas which are lacking in detail study. A map of the proposed planning area is attached as Exhibit A. 16. A description of the existing or potential flood hazard that this planning is intended to address and the way in which the proposed planning will address the problem. The existing flood hazard faced by the City of San Marcos is a combination of flooding and erosion issues in known special flood hazard areas, out-of-bank flooding and erosion in unstudied tributaries, and surcharge in secondary drainage systems. The potential for further flood hazard exists as currently undeveloped areas, both in and outside of the City of San Marcos' jurisdiction, become developed. The proposed planning effort will consider the hydiologic characteristics and hydraulic performance of each watershed in terms of both the existing and "ultimate" watershed condition. One goal of the planning effort is to help not only identifY alternative solutions, but also prioritize them for implementation. Structural flood protection measures may include any combination of channelization, bridge and culvert upgrades, dual purpose flood control 1 water supply reservoirs, and detention facilities. Non-structural flood protection measures may include recommendations for revisions to current drainage policies, buy- out of floodprone property, a creek maintenance program, and a coordinated early warning system in cooperation with GBRA, Hays County, and other technical partners. A second goal of the planning effort is to reduce the flooding risk that is borne disproportionately by the City's lower-income residents. Mitigation measures which can reduce this risk will directly benefit those who are least able to recover from losses incurred in a flood event. In addition, the protection offered by the proposed improvements will protect property values, thereby strengthening the city's tax base and promote reinvestment in these areas of the community. Furthermore, as a byproduct of this planning effort, elevation certificates will be prepared as appropriate, and at no cost to residents. These elevation certificates will directly benefit these policyholders under the NFIP. Byproducts of the planning effort will also contribute to the mission of minimizing the exposure of lives and property. A public meeting will be scheduled to both solicit input from the public and educate the public on flood hazard risks identified in the planning. The maps of the existing and ultimate lOO-year floodplain, with and without recommended improvements, will further serve to educate the public about the nature of M:\active\04P012 St11l Marcos M.D.P\Grt11lt Applic-SMa.dcixhil1it A, Page 11 December 16. 2004