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The goal of this research is to support coastal decisionmakers in North Carolina and South Carolina by providing information about potential future precipitation and sea level conditions under increased climate variability and by examining how industries, community water and sewer districts, and coastal resource managers might adapt to future changes in the freshwater supply. To this end, scientists from the Carolinas Integrated Sciences and Assessments CISA, United States Geological Survey USGS South Carolina Water Science Center, and Advanced Data Mining International ADMi investigated the threat of saltwater intrusion in the YadkinPee Dee River YPDR basin under conditions influenced by ongoing and future climatic change, with an emphasis on changes in the frequency and duration of saltwater intrusion events with increasing sea levels. In addition, project leaders enhanced a decision support system DSS that is relevant and userfriendly to incorporate planning for future coastal climate change. Of central focus in this study was the everpresent need to address how humans will respond to ongoing and future changes in our environment, particularly under climatic regimes that may not have been felt by present society.The primary components of the project included empirical and mechanistic modeling of hydrologic conditions in the YPDR system to determine freshwater discharge and resulting salinity intrusion at the coast under future climatic conditions and sea level rise and updating an existing DSS to address saltwater intrusion challenges for resource managers, industry, and water and sewer districts in the study basin. The project team used the Environmental Protectin Agency EPA BASINS HSPF model and the Pee Dee River and Atlantic Intracoastal Waterway Salinity Model PRISM Conrads and Roehl 2007 to conduct the empirical and modeling analysis. The updated PRISM2 DSS allows users to adjust sea level rise and flow levels in the YPDR basin to generate scenarios of how future climate change e.g., the potential for more frequent drought conditions and sea level rise may impact the inland penetration and duration of saltwater intrusion events.The S.C. Sea Grant Consortium, CISA, and the North InletWinyah Bay National Estuarine Research Reserve NERR held a stakeholder workshop on December 14, 2011, in Georgetown, SC, to discuss saltwater intrusion planning challenges and information needs with regional decision makers and to obtain their input regarding the utility of the PRISM2 DSS. Participants were introduced to three alternative flow scenarios that simulated potential impacts from climate change and its resulting effects on the frequency and longevity of saltwater intrusion events in relation to decreased streamflow and rising sea levels. Workshop participants highlighted several major ecological and water supply infrastructure concerns that would have to be addressed under the provided scenarios. They also contributed salient feedback regarding additional needs for information, planning tools, and procedures. Relevant to the interests of regional stakeholders, the PRISM2 DSS demonstrated the effects of salinity intrusion events on the frequency and duration of higher conductance values in water sources. Such events are problematic for the operations of municipal water treatment plants when the specific conductance values for source water are greater than 1,000 to 2,000 Scm. Participants suggested that with the addition of further pertinent information e.g., 4 ecologicalspecies salinity thresholds, the PRISM2 DSS can help decisionmakers plan for future severe events e.g., positioning freshwater intakes and treatment facilities, preparing for increased treatment costs while increasing the regions resilience by encouraging preparation for potential changes in the frequency and magnitude of saltwater intrusion events.