Hurricane David, a Category 5 hurricane with winds of 175 mph, formed in the Caribbean in late August 1979, made landfall in the United States, and moved up the East Coast. It made a direct hit on Baltimore on September 5 and, though downgraded to a tropical storm, dumped more than 8 inches of rain in a short time. Mount Washington suffered extensive damage. The Western Run stream, adjacent to the Arboretum on its southern side, overran its banks and flooded the area; the ground floor of the complex was flooded and cars were washed away. Several years later, the apartments were condemned by the city and demolished, leaving an empty lot that two decades later would become the Arboretum. To guard against future floods, the Arboretum has several walls and berms built perpendicular to the flow of water.