About
After experiencing two historic floods in less than two years, Ellicott City was in desperate need of plan for flood mitigation that enhances public safety, retains the city's historic charm, and provides a sense of security to businesses, residents, and property owners.
The Ellicott City Safe and Sound Plan encompasses those values as a guiding principle through its comprehensive and innovative approach to flood mitigation. The Plan outlines seven major infrastructure projects designed to reduce flooding in Historic Ellicott City. These projects include two water conveyance projects and five water detention projects throughout the watershed. When complete, these projects will work together to reduce the quantity and velocity of water on Main Street during major storm events.
Completed Projects
H-7 Flood Mitigation Pond
Completed in October 2022, the H-7 Pond was constructed on state land in a clover-leaf interchange at the intersection of Route 29 and Route 40/Baltimore National Pike in Ellicott City. While the pond will typically remain dry, it has the capacity to hold more than 4.2 million gallons of water, restricting the flow of water away from Historic Ellicott City. As part of this construction project, 110 trees and 1,800 native plants were planted.
Click here to watch a video and learn more about the H-7 Pond.
Quaker Mill Pond
Completed in February 2023, the Quaker Mill pond was constructed along Rogers Avenue in Ellicott City. This detention pond has the capacity to hold more than 3.3 million gallons of water during storm events, restricting the flow of floodwaters away from Main Street. As part of this project, the County also planted 150 trees with this project, which enhances the stability of the embankment and efficacy of the pond.
Click here to watch a video and learn more about the Quaker Mill Pond.
Projects In Construction
H-4 Pond
The H-4 Pond is a water detention pond that will be located along Frederick Road west of US29. Once complete, this project will have the capacity to hold more than 5.5 million gallons of water during storm events, directing water away from Historic Ellicott City.
Construction on the H-4 Pond began in June 2024. Weather permitting, this project is expected to take approximately 15 months to construct and is expected to be fully operational in the Fall of 2025. Click here to watch a video of the construction progress on the H-4 Pond from November 2024.
When complete, the combined stormwater capacity of the H-7, Quaker Mill and H-4 ponds will be more than 13 million gallons – roughly the equivalent of a football field filled 30 feet deep with water.
Extended North Tunnel
About the Extended North Tunnel
The Extended North Tunnel is a focal point of the EC Safe and Sound Plan. The North Tunnel is a water conveyance project that will carry flood waters from the West End of Ellicott City through an 18-foot-diameter, underground tunnel to the Patapsco River. This project will reduce the risk of flash flooding by intercepting water from the western portions of town and diverting it underground and away from Main Street. Final design for the Extended North Tunnel is complete, and CSX Transportation has provided conceptual approval.
Construction - Papillon Drive Site
Construction on the North Tunnel began in June 2024 near Papillon Drive in Ellicott City. At the Papillon Drive construction site, Howard County is creating the mining shaft for the Tunnel Boring Machine and a drop shaft for floodwaters. The Tunnel Boring Machine will begin drilling journey at this site. Click here to see a video on the construction of the mining shaft at the Papillon Drive site, taken in January 2025.
Construction - Tunnel Outfall Site
Construction of the North Tunnel outfall site at the Patapsco River began in May 2025. During the period of construction, Parking Lot B in Ellicott City is closed to the public. The outfall site is where the Extended North Tunnel will release water into the Patapsco River.
Construction Timeline
Construction will take approximately three years, with expected substantial completion in Fall 2027.
Tunnel Alignment & Tunnel Boring Machine
Howard County will use a massive, 300-foot-long tunnel boring machine to excavate through solid granite at depths more than 100 feet below the surface. Several drop shafts located at various places in town will be used to capture water from Main Street and convey it through the tunnel to the Patapsco River. The Tunnel Boring Machine has been affectionately named "Rocky" by public vote.
Projects in Design
Maryland Avenue Culverts
The Maryland Avenue Culverts are a water conveyance project that will install a new pair of pipe culverts from Lower Main Street into the Patapsco River. This project will better convey water from the Tiber River into the Patapsco River during severe weather events.
Final design for the Maryland Avenue Culverts is underway, and CSX Transportation has provided conceptual approval for this project.
NC-3 Pond
The NC-3 Pond is a water detention pond that will be located on the New Cut branch in Ellicott City. This project is anticipated to hold approximately 63-acre-feet of water, which is the equivalent of more than 20 million gallons of water.
The NC-3 Pond is currently in the final design and permitting stage.
T-1 Pond
The T-1 Pond is a water detention pond that will be located on the Tiber tributary in Ellicott City. This project is anticipated to hold approximately 70-acre-feet of water, which is the equivalent of more than 22 million gallons of water.
The T-1 Pond is currently in the planning and preliminary design stage. In September 2024, Howard County began the preliminary design phase of the T-1 pond. County contractor GreenVest is overseeing Phase 1 of the T-1 Pond project, which will define the scope, cost and schedule for the project’s final design and implementation.
Flood Mitigation Strategy
Collaborative Funding Efforts
In conjunction with state and federal partners, the County has secured substantial funding to make these projects a reality. To date, the County has assembled more than $300 million in local, state, and federal funding to advance these flood mitigation projects. This funding package includes a competitive, $75 million Water Infrastructure Finance and Innovation Act (WIFIA) loan through the Environmental Protection Agency, more than $100 million in local funding, and more than $75 million in State and Federal grants secured. This significant commitment of local, state, and federal funding underscores the collaboration needed to advance this comprehensive plan.
Expert Validation
Our flood mitigation plan has received an endorsement from a national team of experts assembled by the U.S. Army Corps of Engineers (USACE). Their affirmation speaks to the soundness and feasibility of our chosen strategies. In their review and evaluation of the Ellicott City Safe and Sound Plan, USACE concluded that the County followed a comprehensive process and that the County flood mitigation plan could significantly reduce flood risk to downtown Ellicott City.
Developing the Plan
Upon taking office in December 2018, County Executive Calvin Ball initiated the Ellicott City Safe and Sound Plan and immediately directed the Department of Public Works (DPW) to develop options for flood mitigation using those values as guiding principles. After analyzing more than 70 potential scenarios, the County Executive selected the five options that best achieve the desired outcomes to present to the community for comment and discussion. The community was given an opportunity to comment on these options via email, the website, or at a public meeting on May 2, 2019.
After reviewing the comments and conferring with experts, County Executive Ball selected option 3G.7.0. This bold plan is the best available option to move forward with urgency, prioritize public safety, and build a model of resilience. This plan was reviewed by a national team of experts assembled by the Army Corps of Engineers. In their report, the Army Corps affirmed that the County is following a sound process and that the projects included in the county's plan can significantly reduce flood risk to Historic Ellicott City.
Frequently Asked Questions
How will the county pay for these projects?
We have been and continue to actively pursue state and federal grants, and are also using county funds to pay for the projects. Since taking office, County Executive Ball has worked with partners at the state and federal level to secure more than $300 million in funding for flood mitigation and related projects in Ellicott City. This includes a $75 million WIFIA loan through the Environmental Protection Agency and more than $75 million in state and federal grant funds.
When will construction be completed?
As of August 2025, two Safe and Sound projects have had construction completed: the H-7 and Quaker Mill Retention Ponds. The H-4 Pond is currently under construction and expected to be complete in Fall 2025. The Extended North Tunnel is under construction and expected to be complete in Fall 2027. Other projects will be completed as quickly as possible pending the completion of required design and permitting activities and pending funding availability.
What impact will these projects have on businesses and residents in Ellicott City and on the West End?
The largest impact will be around the construction of the Maryland Avenue Culvert, which could lead to road closures on Maryland Avenue. The exact impact is still being evaluated. Other projects should cause minimal or no impacts to businesses or residents in Ellicott City. For businesses and residents on the West End, temporary lane closures for the construction of the new culverts are anticipated.
When will acquisitions be completed?
All of the buildings on lower Main Street that the county intended to acquire have been purchased.
The county included the 100-year storm and the July 2016 in the analysis. Why didn't you show how the improvements would perform in the May 2018 storm?
Based on modelling data, the July 2016 storm produced the worst flooding so this storm was used to benchmark the flood mitigation options.
What does it mean when a bid is advertised?
When a bid is advertised, a date is selected for interested and qualified contractors to submit a proposal for the work. This task is managed by the Office of Procurement and Contract Administration, which collects applicable technical documents, and posts the opportunity in the public domain.
What's the difference between preliminary design and final design?
Preliminary design generally includes activities to develop and evaluate concepts for the proposed work, and select a concept. This typically includes development of a conceptual cost estimate, as well as design and construction schedules which inform future budget requests. Final Design builds upon the preliminary design, and includes all technical documentation required to construct the project. This includes all required permitting.
Why do capital projects take so long?
Planning work for a significant Capital Project may start several years before an improvement is realized and involves several steps. There is typically also significant coordination required with external entities that can add to the overall timeline.
Why are you not showing expected completion dates for the projects?
Estimated completion dates are most accurate once the permitting and bid processes are complete. As more accurate information is available, the tracker will be updated.
Are there plans to rebuild Caplan’s?
Since the County has acquired the former Caplan’s Building, significant measures have been implemented to stabilize the front portion of the building. This includes removing flood debris, installing permanent shoring and bracing, and planning for future improvements. The County is constructing dry floodproofing at the new rear (south) side of the building and is proceeding with reconstruction of a resilient façade fronting Main Street. The Caplan's Building renovation is expected to be complete in Fall 2025. When complete, the Caplan's Building will be re-opened as a retail incubator space on Main Street, supporting small businesses and emerging entrepreneurs.
Why did Caplan’s get so damaged?
Caplan’s is situated at the bottom of the hill where Main Street turns, which makes Caplan’s both a focal point of the streetscape and more vulnerable to damage from flooding. Caplan’s is the first building along Lower Main Street that is built over the stream channel; and it has taken the brunt of the damage along the rear of the building from strong flood waters and storm debris.
What are the plans for the county-owned buildings on Lower Main Street?
The buildings purchased by the county will remain a public asset until all flood mitigation projects are complete. The portions of the building structures over the stream channel have been deconstructed and removed in order to remove constrictions on the stream channel.
The county completed a federal section 106 review in order to perform that work and is developing plans for renovation and reuse of those buildings. In the meantime, all of the building interiors have been cleared of storm debris and water-damaged finishes. Many storefronts along Main Street have been rebuilt with display windows in order to provide a weather resistant and attractive façade while final plans are developed and approved.
Can the existing buildings along Lower Main Street be restored to the pre-2018 flood conditions?
The buildings along Lower Main Street will need to change based on hydraulic studies. No first-floor structures can remain over the stream channels.
What work has been completed on Lower Main Street?
Extensive work has been ongoing on the county-owned buildings on Main Street:
- All of the properties acquired by the county were initially assessed for structural integrity. Most buildings have also undergone some degree of clean out and/or repair activities.
- New doors or windows were installed at 8081 Main Street (Tea on the Tiber), 8085 Main Street (Portalli’s), 8095 Main Street (Shoemaker Country) and 8111-8113 Main Street. Façade repairs and shadowboxes were also completed at 8085 Main Street, 8095 Main Street, and 8111-8113 Main Street.
- Several buildings, including the former Caplan’s Department Store at 8125 Main Street had basements filled in to further ensure structural integrity. Mold remediation work was also completed as needed.