In June, days of heavy rains and snowmelt led to the flooding of Yellowstone River and rivers in other parts of Montana, Wyoming and Idaho, causing what the U.S. Geological Survey referred to as a “1 in 500-year event.” The flooding destroyed bridges, swept away roads, spurred mudslides, led to the evacuation of more than 10,000 visitors and temporarily closed Yellowstone National Park. Immediately following the flooding, local GIS officials contacted USGS and Woolpert to procure lidar data recently collected across Yellowstone and Park County, Mont., to aid in their response. Steven Jay, Park County GIS/IT analyst, said the data, including collections over many remote and densely forested areas, is needed to model the terrain, prioritize areas at a higher risk of flooding and identify areas of erosion.