During September 12-15, 2008, rainfall ranging from 2 to more than 11 inches fell on northwestern Indiana. The rainfall resulted in extensive flooding on many streams within the Lake Michigan and Kankakee River Basins during September 12-18, causing two deaths, evacuation of hundreds of residents, and millions of dollars of damage to residences, businesses, and infrastructure. In all, six counties in northwestern Indiana were declared Federal disaster areas. U.S. Geological Survey (USGS) streamgages at four locations recorded new record peak streamflows as a result of the heavy rainfall. Peak-gage-height data, peak-streamflow data, annual exceedance probabilities, and recurrence intervals are tabulated in this report for 10 USGS streamgages in northwestern Indiana. Recurrence intervals of flood-peak streamflows were estimated to be greater than 100 years at six streamgages. Because flooding was particularly severe in the communities of Munster, Dyer, Hammond, Highland, Gary, Lake Station, Hobart, Schererville, Merrillville, Michiana Shores, and Portage, high-water-park data collected after the flood were tabulated for those communities. Flood peak inundation maps and water-surface profiles for selected streams were made in a geographic information system by combining high-water-mark data with the highest resolution digital elevation model data available.