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Eugene -Springfield Area Natural Hazards Mitigation Plan 2. Hazard Descriptions 2.6.2 Climate Change Though the full extent of climate change's effect on flooding is unknown, existing research shows it will influence this hazard. Summer precipitation is projected to decline by as much as 30%. This will be accompanied by less frequent, but heavier downpours.46 Already, the Northwest has experienced a 12% increase in very heavy precipitation incidents (the heaviest 1%) from 1958 to 2012.47 Though there are many contributing factors for flooding, climate change is expected to increase flood risk in water basins with both rainfall and late spring snowmelt-related runoff peaks. Warmer winter temperatures will lead to more precipitation falling as rain instead of snow, which reduces the amount of water stored as snow and increases wintertime river flows. Increased potential for heavier precipitation incidents will also exacerbate the risk of flooding. The Oregon Climate Change Adaptation Framework lists 11 risks including "increased frequency of extreme precipitation incidents, and incidence and magnitude of damaging floods."48 2.6.3 History of the Hazard in Eugene -Springfield Flooding has been recorded in Eugene and Springfield ever since the first European settlers arrived in the area in the mid- 1800s. The FEMA Flood Insurance Study (FIS) for Lane County (June 2, 1999) summarizes the history of major historical floods in the Eugene- Springfield area. Major floods occurred in 1861, 1890, 1945, 1956, 1964 and 1996. The 1964 flood was the largest flood incident recorded in Lane County. Notably, the construction of flood control dams in the 1940s-1960s has substantially reduced the potential for significant riverine flooding in Eugene and Springfield. These dams have reduced the expected base flood discharges of water flowing into the local rivers. Accordingly, expected flood elevations and overall flood potential for major incidents along the rivers have been substantially reduced. In addition to the flood control dams, the U.S. Department of Agriculture Soil Conservation Service (now known as the Natural Resource Conservation Service) and Lane County constructed a flood control levee in 1960 to protect a large area of Springfield from McKenzie River flooding. Ownership and maintenance responsibilities for this levee transferred to the City of Springfield in 1983. This 46 U. S. Global Change Research Program. Climate Change Impacts in the United States: The Third National Climate Assessment. By Jerry M. Melillo, Terese Richmond, and G.W. Yohe. 2014. 487- 513. 47 United States. Environmental Protection Agency. Office of Policy. Adapting to Climate Change Northwest. June 2016. Accessed November 13, 2017. EPA-230-F-16-018 https://www.epa.gov/sites/production/files/2016-07/documents/northwest_ fact_sheetpdf 48 The Oregon Climate Change Adaptation Framework. Oregon Department of Land Conservation and Development. December 2010. https://drought.unl.edu/archive%lans/Climate/state/OR 2010.pdf 2-30 January 2020