The Stormwater Challenge In Ellicott City

July 31, 2014
Jim Caldwell
Howard County Initiatives

The Patapsco River and Ellicott City share the best of times and the worst of times. The river powered the Ellicott Brothers’ mill which spawned the city’s growth and prosperity in the late 1700’s and beyond. That same river, however, periodically brings the city despair. Flood waters ravaged the historic town many times over the last two centuries including major events in 1868, 1952, Agnes in 1972 and Eloise in 1975. As the city grew so did rooftops, sidewalks, roads and parking lots. All these impervious surfaces create more storm runoff and greater flooding potential. Now, the problem not only comes from the Patapsco overflowing its banks. As we learned with Tropical storm Lee this past fall, upstream storm drains and Tiber Creek cannot always channel the rain water rushing to the Patapsco – and the streets themselves become rivers.

Stormwater management in general is a big challenge as federal and state mandates to control both the volume and quality of storm runoff continue to get more and more stringent. Historic Ellicott City presents an even greater stormwater challenge considering the town’s age, amount of impervious area, steep slopes, low point in the watershed and lack of open space to manage runoff with conventional designs. By now we all know there is no silver bullet and the solution must lie in a series of projects, some of which correct existing problems and others that focus on new controls.

First we face the challenge of keeping the channels and the creeks running through the town free of storm debris. County maintenance staff, area residents and the Patapsco Heritage Greenway volunteers were instrumental in removing debris following tropical storm Lee. Yet, as each new storm comes, the potential for more debris dams and channel blockage exists. This requires that we keep a constant vigil to locate and address these problems. Debris removal can get a bit complicated at times due to the issues of public versus private property, but working together we can keep the channel as free moving as possible – considering the twists and turns inherent in the densely developed Tiber/Hudson tributary.

Second, there are long-term engineering projects getting underway to assess potential bottle necks in the waterways. Working with the residents of the area who know firsthand where the problems develop, we will define ways to remove or reduce these choke points through channel or structure modifications. Like all engineering solutions this will take time and it is anticipated that actual construction may be a few years away. These studies will focus on areas upstream of the main street business district in hopes of controlling runoff before it gains momentum heading for the Patapsco. Of course, during planning and design if we identify any quick fixes we will address them in a timely manner.

The key to good stormwater management is to get the rain water back into the ground as close to where is falls thereby reducing the torrents that run to the nearest stream and in worst case overflow that channel causing floods. Finding open land for infiltration in an area that is so densely covered with homes and asphalt is a challenge. But it can be done. Just last month we held a day-long design round table with a group of engineers who specialize in innovative stormwater designs for urban areas. While these projects will not stop flooding, they will help reduce the volume of water running to streams and serve to reduce the initial runoff surge. We are excited by some of the designs suggested during our round table and hope to soon add some of these concepts to our overall strategy to manage stormwater in the historic area.

As noted earlier, there is no silver bullet that will address the potential for flooding in the Ellicott City area. Unfortunately, flooding during big storms is part of the community’s history. While we have made some progress in managing flows over the years, it is clear to everyone that we have a ways to go in protecting the welfare of the community and the quality of our resources in the area. Be assured that this is a priority of Howard County. However, to reach our goal we will need to work together and recognize the unique challenge created by this historic area.

Jim Caldwell
Stormwater Manager