Flood Mitigation Plan

After experiencing two historic floods in less than two years, Ellicott City was in desperate need of plan for flood mitigation that protects public safety, provides a sense of security to businesses, residents, and property owners, and retains the city's historic charm. 

Upon taking office in December 2018, County Executive Calvin Ball immediately directed the Department of Public Works (DPW) to develop options for flood mitigation using those values as guiding principles. Utilizing the information provided in the 2016 Ellicott City Hydrology/Hydraulic Study, DPW worked with the author of the report to reanalyze potential projects to see how to most effectively reduce the amount of water on the street on Lower Main Street and the West End while preserving as many buildings as possible. 

After analyzing over 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 2nd.


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 is was recently reviewed by a national team of experts assembled by the Army Corps of Engineers. In their report, the Army Corps affirmed that hte 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. 

Flood Mitigation

Options Comparison

*Average depth from Caplan's to Maryland Avenue during July 2016 storm conditions.

Water Depths Comparison

*Maximum depth reflects water depths on Lower Main Street above Maryland Avenue. 

Water Velocity


Values generated using the 2016 storm

Frequently Asked Questions

When will construction begin?

Design is already underway for some of the projects and construction will begin as early as this summer for some of the projects. The start date for the majority of the projects is dependent on which flood mitigation scenario is selected. It is expected that, regardless of which scenario is selected, construction will begin for most projects during FY20 and FY 21.

When will construction be completed?

This will vary depending on the mitigation scenario that is selected. Under optimal conditions, construction could be completed within 4 to 7 years.

What impacts will the projects have on the businesses in Ellicott City?

For the most part, impacts to Main Street will be brief. We anticipate temporary lane closures on Main Street during building demolition, which will take approximately 2-3 weeks to complete.

What impacts will the projects have on residents and businesses on the West End?

Temporary land 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 intedned to acquire have been purchased. Acquistions continue for proeprties in the West End.

The county included the 100-year storm and the July 2016 storm 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.

How can we follow the progress of the construction?

The county has created a project tracker that will show the progress of each project along with the anticipated completion date. The tracker is currently under construction but should be available soon.

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 $16 million in funding for Ellicott City.

How were the cost estimates for the tunnels determined?

The cost estimates were based on 3 engineering estimates. However, a Request for Proposals (RFP) will be issued that will help to better determine the cost. The most qualified applicants will be asked to submit their cost proposals. The successful applicant will be the one deemed most qualified at the lowest price.