The Dayton flood of March 1913 was caused by a series of severe winter rain storms that hit the Midwest in late March. Within three days, of rain fell throughout the Great Miami River watershed on already saturated soil, resulting in more than 90 percent runoff. The river and its tributaries overflowed. The existing levees failed, and downtown Dayton was flooded up to deep. This flood is still the flood of record for the Great Miami River watershed. The volume of water that passed through the river channel during this storm equaled the monthly flow over Niagara Falls.