On July 30, 2016, Ellicott City, Maryland, faced a devastating flash flood following torrential rainfall, resulting in severe damage to the historic Old Town area. Two fatalities occurred, and numerous buildings and vehicles were affected. The National Weather Service’s analysis indicated an extremely rare probability of such rainfall, causing a sharp rise in streams. The Patapsco River, a major impact area, rose over 13 feet in 100 minutes, earning the flood it’s unfortunately ironic moniker “The Thousand Year Flood,” which ended up reoccurring just shy of two years later in 2018.
Within just 22 months, Ellicott City and Catonsville faced another torrential rainfall event on May 27, 2018, causing catastrophic damage, particularly in Historic Ellicott City. With heavy rainfall between 6 and 12 inches, the region experienced severe flooding, resulting in one fatality and significant property and infrastructure damage. The National Weather Service had issued warnings and watches, anticipating the potential for flooding. The first wave of rain caused the Tiber River to overflow, leading to flash flooding on Main Street. A Flash Flood Warning was issued as conditions rapidly worsened, with water levels peaking up to the top of the first floor of buildings. A second round of heavy rain further exacerbated the situation, prompting stronger warnings. The Hudson Branch and Tiber Alley experienced rising water levels, reaching almost equal levels to the 2016 flood. The event prompted a Flash Flood Emergency, and a third round of rain was anticipated but weakened, avoiding a third flood wave. The Patapsco River played a lesser role than in the 2016 event, peaking at a lower elevation. While Ellicott City received significant attention, Catonsville, Baltimore City, and Dundalk also faced substantial flooding. Social media images depicted flooded streets, damaged roads, landslides, and water rescues in various areas.
A survey conducted by the National Weather Service, Howard County Office of Emergency Management, and Howard County Department of Public Works following the 2016 flood revealed signs of flooding from both the Patapsco River and flash flooding within Ellicott City. Damage extended from the intersection of Rogers Avenue and Frederick Road to the Baltimore County side, with significant destruction near 8100 Main Street. A survey in the days after the flood highlighted high water marks, vehicle impacts, and the force of floodwaters that swept away iconic landmarks. The aftermath prompted Howard County to conduct a comprehensive case study on the damage and water movement pathways in the affected area.
Information courtesy of National Weather Service