Flood Prevention Plan's Largest Pond To Hold 5.5M Gallons Of Water: Howard County Official

HOWARD COUNTY, MD — Officials have broken ground on the third and largest stormwater retention pond in Ellicott City's Safe and Sound plan.

The H4 dry flood mitigation pond should be completed by late September 2025. It will hold up to 5.5 million gallons, the equivalent of a football field that's 12.8 feet deep, which would otherwise flow directly into the Tiber-Hudson River and down to Main Street. The pond will be constructed along the north side of Frederick Road just west of US 29.

The nearly $4 million project is supported by $1.32 million in local funding from the Howard County Government and a $2.64 million in state funding through the Comprehensive Flood Management Grant administered by the Maryland Department of the Environment.

The Ellicott City Safe and Sound plan calls for five large-scale water retention projects, along with major water conveyance projects, enhanced stream inspections and debris removal after weather events, a tone alert warning system and high-ground signage, and drainage improvements throughout the watershed.

The plan was created to help protect Ellicott City from any further flood damage. The town battled catastrophic floodwaters in 2011, 2016 and 2018. The full plan can be found here.

"Since establishing our Ellicott City Safe and Sound flood mitigation plan, we have pushed to build this long-needed stormwater infrastructure. The third of seven major public works projects to commence construction under our plan, the H-4 Pond is another giant leap in securing our historic town’s resiliency and the community’s protection for years to come," Howard County Executive Calvin Ball said at the groundbreaking ceremony.

In October of 2022, Howard County finished construction of the H-7 pond located at the interchange of Routes 29 and 40, followed by construction of the Quaker Mill Pond at the intersection of Rogers Avenue and Patapsco River Road in February of 2023. Together, these two facilities have the capacity to collect and control the release of 7.5 million gallons of water during a storm. The completion of the H-4 pond will add another 5.5 million gallons of water capacity, which will bring total retention to approximately 13 million gallons of water during severe storms - equivalent to a football field filled with water that is 30 feet deep.

“As a small business and property owner on Historic Main Street, I support the county’s ongoing efforts to provide flood solutions that will safeguard Old Ellicott City, its businesses and its visitors for the future,” said Maria Martinez, owner of Primitive Beginnings. “Projects such as the H4 pond and the two completed stormwater ponds are instilling confidence in business owners and visitors, encouraging them to invest in the area and feel secure when visiting OEC.”

“Starting my business in Historic Ellicott City after two floods and a pandemic was a risk. However, I was confident county leaders would recognize the importance of this community and invest in sustainable solutions to keep it thriving. We are already seeing the benefits of their work,” added Alli Krist, owner of Backwater Books.