Table 1.

Precipitation-caused sewage overflows in ten U.S. municipalities between 1 May 2020 and 10 August 2020.

City/state	Datea	Precipitation (mm)b	Estimated volumes of sewage overflowc & affected area sized
Chicago, Illinois	May 14–15	114.3 mm (max.) in two days	Several million gallons of human and industrial wastes with runoffs flowed into the city's waterways and Lake Michigan, while flooding the streets and basements at some locations.
Havelock, North Carolina	May 19 & 22	102–127 mm (May 18); 64–76 mm (May 22)	In two separate events, 277,150 gal (ca. 1049 m3) of untreated sewage overflowed from several manholes on three streets in a school & residential area, and one near a church.
Midland, Michigan	May 19–22	38.0–51.0 mm (max.)	Untreated sewage overflowed from a sewage treatment plant and a chemical manufacturer (volumes unknown) into a creek and a lake nearby, with 10,000 evacuated.
Miami-Dade, Florida	May 25 & 28	152–203 mm (max., on May 25 & 27)	In two separate events, 1.8 million gallons (ca. 6814 m3) and 10,000 gal (ca. 38 m3) of sewage spilled from a sewage treatment plant, contaminating a state park and adjacent waters.
Wilmington, North Carolina	June 16	33.5 mm	59,000 gal (ca. 223 m3) of untreated sewage overflowed from a manhole outside of a sewage pumping station located in a commercial/residential area, and discharged into a creek nearby.
Augusta, Georgia	July 6–7	154 mm (two-day total)	385,625 gal (ca. 1460 m3) of rainwater mixed with sewage overflowed from several street manholes in commercial/residential areas, and end of the collection system near a park.
Edgewater, Maryland	July 25	83.1 mm	17,000 gal (ca. 64 m3) of untreated sewage overflowed from a sewer main near a river bank, and spilled to the beach and the river nearby.
Baltimore, Maryland	August 4	54.6 mme	530,000 gal (ca. 2000 m3) of untreated sewage overflowed from 17 locations (some located in densely populated areas near the city center), and spilled into the city's waterways.
Aberdeen, Maryland	August 4	101.6 mme	178,000 gal (ca. 674 m3) of untreated sewage overflowed from a cross street in a commercial/residential area, ran a few miles in stormwater drainage ditches, and spilled into a creek.
Orlando, Florida	August 8–9	90.4–123 mm	350,000 gal (ca. 1325 m3) of untreated sewage overflowed from a pumping station in a park due to power outage caused by thunderstorm and discharged into two nearby lakes.

^aBased on the local time when sewage overflows occurred. Ranges indicate reoccurring events.

^bPrecipitation data were obtained from public statements issued by local municipalities. When such data were unavailable, quantitative daily precipitation estimates, which were given as bands at half-inch increments by U.S. National Weather Service, were used (https://water.weather.gov/precip/index.php). Precipitation data were converted to metric units.

^cMost quantities were given as estimates by local municipalities.

^dInformation on surroundings was obtained from Google Maps based on the location of sewage overflows given in public statements.

^eRainfalls brought by Tropical Storm Isaias.