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Measuring the impact of flood management strategies on flooding and water quality in a historic residential neighborhood

Ellicott City, Maryland

Featured image for the project, Measuring the impact of flood management strategies on flooding and water quality in a historic residential neighborhood

Homes in the 8600 Main Street neighborhood of Historic Ellicott City, Maryland, many of which are immediately adjacent to the Hudson Branch tributary of the Patapsco River, are highly threatened by flooding and associated runoff pollution. These risks are exacerbated by the recent approach to flood management, which relies upon an 108” culvert, which is well past its lifespan, that intensifies the volume and flow rate of floodwater in the neighborhood. The county’s flood management strategies are currently being reevaluated but there is no indication that preservation of residents’ homes is a priority in this decision process. Community residents have identified many potential alternative approaches, including many nature-based strategies, to mitigate the flood risk using locally available resources. Our objective is to quantify the floodwater volume and velocity as well as water quality concerns associated with different flood management strategies and identify possible nature-based solutions that could be implemented on a local scale. This information would allow neighborhood residents to advocate, as well as seek funding and other support, for improved flood management approaches, which are deeply needed so that residents can remain in their homes and mitigate the risk of catastrophic flooding.


The Community and the Challenge

The 8600 Main Street neighborhood is located in the West End Main Street community of Historic Ellicott City, Maryland, a historical mill town on the Patapsco River. The neighborhood borders the Hudson Branch tributary of the Patapsco, a short distance upstream from the downtown district. Though located in a wealthy county, the neighborhood faces the loss of generational wealth and heritage; it is threatened by gentrification and a growing risk of catastrophic flooding, and many heritage residences have been acquired by the county. There are around 60 homes in the West End of Main Street as well as other heritage communities along the periphery of Main St and local tributaries that are threatened by severe flash flooding.

The 8600 Main Street neighborhood is working with Thriving Earth Exchange to gather resources to enable efforts to protect and preserve the heritage community. They aim to move beyond a focus on rebuilding after flooding to a new framework of building long-term resilience. Residents are engaging with a wide range of resources to build resilience, and they hope that scientific data produced in partnership with Thriving Earth Exchange can galvanize and support their ongoing efforts to preserve their community.

For more information on the challenges facing Historic Ellicott City and their work to build resilience, you can view the following resources:


The Project

We aim to collect data to articulate multiple components of the flood risk threatening the 8600 Main Street neighborhood along the Hudson Branch:

  • Floodwater volume. The current culvert was reduced in size following the 2011 flash flooding and is not sufficient to reduce the volume of floodwater that threatens homes along Main Street during flooding and may even exacerbate risks by redirecting and increasing the floodwater velocity around homes. At the same time, green infrastructure features that historically reduced flood risk, including floodplain walls, floodplains and plunge pools, were damaged in 2011 flash flooding and since have been neglected and continue to remain dysfunctional. We aim to quantify the impact of current channel management (or lack of) on flood risk and estimate the impact of alternative strategies.
  • Water quality concerns. Floodwater washes over a local commercial property, potentially picking up contaminants that are then carried through residents’ properties and homes. We aim to identify these contaminants and any associated risks, and to identify possible solutions that could be implemented on a local scale.
  • Potential nature-based approaches to mitigating flood risk. There are several local resources that could provide opportunities to mitigate flood risk, including the following: land that could potentially be used for floodwater detention; existing vegetation as well as opportunities to expand vegetated buffers on residents’ riparian property; a record of historical green infrastructure that was previously successful in lowering flood risk and could possibly be restored.

The community hopes to make the results of this project available to relevant governing bodies and management agencies at the municipal, state, and/or federal level. Neighborhood residents also plan to use the results to inform their advocacy for effective flood risk solutions and in applications for funding and other external support to implement solutions. Flood risk mitigation strategies for the Hudson Branch are currently being reviewed as part of broader discussions of watershed management, so there is some urgency in obtaining data to inform residents’ participation in this decision process.

Project deliverables will likely include data reports and visualizations related to floodwater volume and velocity, water quality concerns, and the potential role of nature-based flood mitigation. These will be provided to community members and are intended to be used for communicating with municipal and state government entities in upcoming flood management decision processes.

A new flood management strategy is necessary for residents of the 8600 Main Street community to continue living in their neighborhood and avoid serious risk to their homes and lives. The data we plan to collect through this project are expected to significantly improve residents’ ability to participate in decisions about flood management in their neighborhood and to advocate for a new approach to flood management that mitigates the risk to their heritage community. They are eager to collaborate and share knowledge with the many communities across the country facing similar flood risks.


Timeline and Milestones

  • The project should begin as soon as possible due to the existing flood risks facing the community.
  • A review of flood management strategies (CWA Section 404) for the Hudson Branch watershed is underway, though the timeline for this process is not currently known. The community hopes to use results obtained from this project to inform their participation in this decision process and to support their ability to advocate for evidence-based strategies that mitigate the risk to their neighborhood. 
  • The initial data collection phase may be relatively short in duration, but there may be additional follow-up data collection; details will be worked out with the partnering scientist(s).

Project Team

Community Lead

Gayle Killen has supported community recovery from runoff rapids since 2011, after witnessing devastation in her historic community first hand. She has since flood proofed her home through wet-proofing and rainscaping and works to help the remainder of the community become resilient as well. While not specifically “anti-development”, she recognizes the role that redevelopment plays in historic communities such as her own and strives to preserve as much as possible. Gayle is a certified Wildlife Habitat Naturalist and a Natural Building enthusiast. She has used native rain scapes to collect and manage runoff, reinforced the walls of her 1809 historic Icehouse with Hempcrete, and has installed a TESLA SolarRoof with Powerwall batteries to preserve her historic home located in a Chronic Disaster Zone.


Community Science Fellow

Caitlin Mandeville is an ecologist and PhD candidate at the Norwegian University of Science and Technology in Trondheim, Norway. Her research focuses on conservation applications of biodiversity citizen science, touching on the topic from several perspectives including open data access, intersections between citizen science and outdoor recreation, and the role of citizen science in protected areas. Before her current work, she earned a B.Sc. from the University of Wisconsin-Madison, explored ecosystems around the US through seasonal fieldwork and environmental education positions, earned a M.Sc. from the University of Wyoming researching the impact of temperature regulations on freshwater stream fish, and spent two years coordinating community science programming with New Hampshire Sea Grant. She is passionate about working directly with communities on conservation.


Anthropocene Alliance Partner

Alexis Hidalgo is the Program Manager for Anthropocene Alliance, the nation’s largest coalition of frontline communities fighting for climate and environmental justice, of which the Historic Ellicott City Flood Solutions is a part of. She hopes to continue supporting in any way possible the incredible work that Gayle is doing to merge science and advocacy in her community.


Scientist Wanted

We seek a scientist with expertise in flood risk assessment and management in river systems running through developed/residential areas. The ideal outcomes from this partnership include: quantifying the flood volume and velocity expected from current and potential alternative management strategies; quantifying water quality issues that may arise from floodwater runoff; and identifying possible ways to make use of local green infrastructure resources (open space, riparian vegetation, plunge pools, etc.) to mitigate flood risk in addition to serving other community priorities (for example, recreation).

The community is open to working with multiple scientists each bringing different expertise—for example, hydrologists, engineers, water quality specialists, ecologists, and so on would likely all bring different relevant skills to this issue.

We are very open to working remotely with scientists located anywhere in the USA or elsewhere.


Desired skills and qualifications:

  • Experience with flood risk assessment and management
  • Creativity and interest in nature-based solutions for flood risk mitigation
  • Willingness to think outside the box
  • Motivation to connect science to local concerns
  • Strong listening and collaboration skills
  • Appreciation for historic preservation


Thriving Earth Exchange asks all scientific partners to work with the community to help define a project with measurable  local impact to which they can contribute as pro-bono volunteers and collaborators. This work can also position the scientists and communities to seek additional funding, together, for the next stage.

Interested in volunteering as a scientist? Apply now!