Waterloo is defined by the Cedar River, which bisects the city and flooded to record levels in June 2008, inundating thousands of homes and causing over a billion dollars in damage across Black Hawk County. Dry Run Creek, a tributary in the northern part of the city, also floods during intense spring and summer rainfall. Iowa's continental climate brings polar vortex events that routinely push temperatures below -20°F, and the city's high percentage of pre-1960 housing stock makes burst pipes and aging infrastructure a chronic concern.