One of Ohio’s greatest floods occurred in March 1913, when rivers across the region, including the Great Miami River, overflowed after still-frozen ground could not absorb a 10-inch rainfall, destroying many towns and cities. Some people believed Indian Lake spillway had burst or the reservoir’s banks had eroded away and caused the flooding, but the Corps of Engineers quickly concluded that properties along the Miami River as far as Dayton were flooded hours before any water escaped over the spillway. The reservoir’s existence lessened the disaster, and without it many more lives would have been lost and property damage would have been greater in Sidney, Piqua, Troy, and smaller river communities. An estimated 420 people died in the Miami Valley. In the Indian Lake community, damage was not catastrophic, but almost every home and business was affected, and the Miami and Erie Canal was lost forever when washed-out locks and damaged banks left it beyond repair. In 1914 Ohio passed the Ohio Conservancy Law, creating conservancy districts around the state, and the Miami Conservancy District became the nation’s first major watershed district. It later maintained large-scale flood-control dry dams, flood basins, and levees along several local rivers, while the Corps of Engineers built Lockington Dam north of Piqua and Englewood Dam north of Dayton between 1918 and 1921 to help prevent future flooding. In 2015 the John and Mary Rudolph Nature Area was created, and its 52-acre preserve provides an additional four billion cubic feet of local flood control.