Howard County makes more progress in Ellicott City flood mitigation project

Howard County officials will announce Wednesday an update in a major flood mitigation project in Ellicott City.

The Ellicott City Safe and Sound plan, launched in 2018 after the town was hit by deadly floods in 2011, 2016 and 2018, aims to protect Historic Ellicott City's Main Street from future damage.

The plan includes multiple projects designed to keep water away from Historic Ellicott City.

The projects include five retention ponds and two water conveyance projects, such as culverts under Maryland Avenue and the North Tunnel project. Two retention ponds had been completed as of February.

The county said Tuesday the third and largest H-4 stormwater retention pond located along the north side of Frederick Road, just west of US-29 has now been completed.

The newest pond has the capacity to retain roughly 5.5 million gallons of stormwater that would otherwise flow directly into the Tiber-Hudson River and down to Main Street, the county said. 

Other parts of the plan

In February, the county said it had enhanced stream inspection and debris removal after severe windstorms swept through Maryland.

Since the plan's launch, crews have cleared more than 100,000 pounds of debris from channels in and around the city.

County Executive Calvin Ball in February said storm debris can create blockages during heavy rainfall, causing stream channels to flood.

Under the plan, debris is removed after any weather event that drops two or more inches of rain within 24 hours or produces sustained winds of more than 30 mph.

The mile-long North Tunnel, expected to be finished by fall 2027, will be able to collect and carry 26,000 gallons of stormwater per second, diverting it away from Main Street.

A tone alert system has also been installed and used several times to warn residents of potential flooding