Officials Cut Ribbon On 3rd Largest Retention Pond In Flood Mitigation Plan

ELLICOTT CITY, MD — Leaders have ushered in the next phase of Howard County's flood mitigation project.

On Wednesday, state and local officials cut the ribbon on the H-4 flood mitigation pond. As the third and largest retention pond to be completed as part of the Ellicott City Safe and Sound Plan to date, the H-4 pond will provide more than 5.5 million gallons of storage, which would fill a football field with nearly 12.8 feet of water.

“The completion of this pond marks another giant leap forward in our efforts to implement the transformational EC Safe and Sound flood mitigation plan,” said Howard County Executive Calvin Ball at the ribbon cutting. “The H-4 Pond is our third major retention project to mitigate flood risks in historic Ellicott City. I’m deeply appreciative of all our local, state and federal partners who continue to help us make significant progress on the safety of Ellicott City. We continue to move with urgency, cooperation and resolve, to ensure that Ellicott City’s best days are ahead.”

Of the $4.3 million in project costs, $3.225 million in state funding was provided to support the project through MDE’s Comprehensive Flood Management Grant Program and the remaining $1.075 million comes from county funding.

"We’ve seen firsthand in Howard County the impact that catastrophic flooding has on public health, safety and infrastructure, and this is why the Department of the Environment prioritizes funding for stormwater management projects," said Maryland Department of the Environment Secretary Serena McIlwain at the ribbon cutting. “We are doing our part to protect homes, businesses and families through stormwater management with the help of residents and businesses that make protection strategies reality. Together, we are building safer, stronger communities."

To date, three of the five stormwater retention ponds featured in the plan are now complete, including the H-4 pond, the H-7 pond and the Quaker Mill pond. Combined, these three ponds have the capability of retaining more than 13 million gallons of stormwater runoff during a rainstorm event, which is roughly the equivalent of a football field filled 30 feet deep with water.

As for the two other stormwater retention ponds, the NC-3 pond to be located on the New Cut branch in Ellicott City, and the T-1 Pond to be located on the Tiber tributary, are both currently in the preliminary design stage. Once complete, the NC-3 pond is projected to hold more than 20 million gallons of water and the T-1 pond more than 22 million gallons.

In addition to these five stormwater retention ponds, Ball’s Ellicott City Safe and Sound Plan also includes two stormwater conveyance projects, the Extended North Tunnel and the Maryland Avenue Culverts.

The single largest public works project in Howard County’s history, Ball broke ground on the Extended North Tunnel Project in June 2024. Stretching from the West End to the Patapsco River, this mile-long, 18-foot diameter structure will divert 26,000 gallons of water per second away from Main Street once completed. To get the job done, a 300-foot-long tunnel boring machine named “Rocky," which will arrive in Ellicott City this winter, will excavate its way through solid granite about 150 feet below the surface all the way to the Patapsco River. The county anticipates completion of this project in the fall of 2027.

The Maryland Avenue Culverts project will install a new pair of pipe culverts from Lower Main Street into the Patapsco River to better convey water from the Tiber River into the Patapsco River during severe weather events. Final design for the Maryland Avenue Culverts is currently underway, officials stated.

“The H-4 pond is our largest infrastructure project completed to date, which delivers on flood mitigation while also preserving the natural environment through the retention of close to 6 acres of mature woods adjacent to the pond,” said Yosef Kebede, director of the Howard County Department of Public Works.

In addition to its stormwater retention abilities, the H-4 pond project will include the planting of 560 trees and 370 shrubs on site in the coming weeks, which will return much of the area to green space over time.

Related:

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• Safe And Sound Plan's Tiber One Flood Mitigation Pond Initial Design Phase Started
• Name The Boring Machine To Be Used For The Ellicott City North Tunnel Project
• Groundbreaking Delayed On Extended North Tunnel Project In Howard Co.
• $50M Cost Increase Disclosed For Extended North Tunnel Project
• 5K-Foot-Long Tunnel To Be Built In HoCo To Help With Flood Mitigation
• Extended North Tunnel Project Meeting Planned For July 6 In Howard Co.
• North Tunnel Extension Would Save 9 Ellicott City Buildings
• Ellicott City Flood Prevention Plan Calls For Tunnel, More
• County Exec Updates Community On Ellicott City Safe & Sound Plan
• Residents Updated On Safe And Sound Plan In Ellicott City