Volume 2: Draft Gorst Planned Action Environmental Impact Statement

Gorst Planned Action EIS | AppendicesSea Level Rise ImagesAs noted in Section 3.3 Air Quality analysis of the Draft EIS, by themselves, none of the Gorst alternatives studiedwould cause discernible changes to global climate change. However, increased worldwide GHG emissions areexpected to cause global climate change, and the effects will likely impact the Gorst study area and the PacificNorthwest region. Local impacts are expected to include changes in seasonal temperatures, seasonal precipitationpatterns, or local seawater rise (UW CIG 2012). Based on research conducted by the University of WashingtonClimate Impacts Group and the Washington Department of Ecology sea level is expected to rise within the PugetSound between 3 and 22 inches by 2050 and between 6 and 50 inches by 2100 (UWCIG, et al 2008).The images below show sea level rise extent at 12-inch intervals at high tide in Sinclair Inlet based upon the SeaLevel Rise and Coastal Flooding Impacts Viewer, available at the following link:http://www.csc.noaa.gov/digitalcoast/tools/slrviewer/. As described on the website it is considered a planninglevel screening tool and not an exact analysis:“The purpose of this data viewer is to provide coastal managers and scientists with a preliminarylook at sea level rise and coastal flooding impacts. The viewer is a screening-level tool that usesnationally consistent data sets and analyses. Data and maps provided can be used at severalscales to help gauge trends and prioritize actions for different scenarios.Disclaimer: The data and maps in this tool illustrate the scale of potential flooding, not the exactlocation, and do not account for erosion, subsidence, or future construction. Water levels areshown as they would appear during the highest high tides (excludes wind driven tides). The data,maps, and information provided should be used only as a screening-level tool for managementdecisions. As with all remotely sensed data, all features should be verified with a site visit. Thedata and maps in this tool are provided “as is,” without warranty to their performance,merchantable state, or fitness for any particular purpose. The entire risk associated with theresults and performance of these data is assumed by the user. This tool should be used strictly asa planning reference tool and not for navigation, permitting, or other legal purposes.”The images can be compared to the range of sea level rise in Puget Sound estimated by the University ofWashington, though it should be noted the University’s study was not specific to Sinclair Inlet. Images 1 and 2 show 1 and 2 foot rises, closer to the University’s low range estimate of 3 and 22 inches by2050. Images 3 and 4 show rises of 3 and 4 feet, similar to the middle and upper end of the University’s higher rangeestimate of 6 and 50 inches by 2100. Image 5 shows 5 feet (or 60 inches) of rise and would be higher than the University’s most extreme range of50 inches by 2100.If such levels of rise were experienced at the Sinclair inlet, at the low end of the range, the effects appear to beabsorbed by tidal wetlands. As levels increase, sea level rise could begin to affect developed areas of Sinclair Inlet.In addition, flooding in low lying areas would increase further upstream on Gorst Creek on the northern (uphill)side of Highway 3..C-3