Baltimore rolls out Back River odor-control changes as residents demand relief
Baltimore is pursuing immediate odor-control measures at the Back River Wastewater Treatment Plant after residents near the Dundalk facility described continuing problems at a Sept. 10 town hall.
The city’s Department of Public Works is working on operational issues, including odor scrubbers and hydrogen sulfide controls, while a third-party engineer studies how odors disperse and whether potential sources are located on or off the plant site. The broader odor-abatement plan is not final.
What Baltimore DPW is doing now
DPW told CBS Baltimore that several efforts are underway while the engineering review continues. WBAL reported that the city is addressing issues identified during a Maryland Department of the Environment inspection, including excess sludge in lagoons and broken hydrogen sulfide sensors within odor scrubbers.
Those conditions may contribute to odors, but they do not establish that the plant is the source of every complaint in the surrounding area. The city has not said that its interim work has eliminated the problem, and residents continue to press for faster action.
What the pending analysis will examine
The third-party engineer is conducting an odor-dispersion analysis and assessing possible on- and off-site sources. Baltimore DPW said the work is expected to be completed by the end of 2026 or in early January 2027.
The analysis is intended to help shape recommendations for a comprehensive odor-control plan. Until that review is complete, the long-term measures, costs and schedule for broader abatement remain unsettled.
Residents describe effects on homes and businesses
At the Sept. 10 town hall, residents said the suspected Back River odor has affected daily life near the plant. One resident told CBS Baltimore that the smell sometimes prevents her from opening windows at night. Other residents described strong odors near homes and commercial areas, while Delegate Robert Long said businesses were being affected.
Those accounts describe residents’ experiences and concerns. They do not, by themselves, establish the precise source of each odor event. Baltimore and Maryland officials continue to investigate plant operations, monitoring data and other possible sources.
What state records show
MDE regulates the facility, conducts inspections and data audits, reviews compliance and continues to monitor reported concerns. The agency’s Back River operations page says the plant reached more than 90% permit compliance in 2025 and identifies additional rehabilitation work as ongoing, including sand-filter and digester projects.
MDE’s air-monitoring information identifies hydrogen sulfide as one indicator that can help track wastewater-related odors. The agency also cautions that hydrogen sulfide sensors can detect mercaptan, a natural-gas odorant with a similar smell. Individual sensor readings therefore require context and do not, by themselves, prove the source of an odor.
Residents can review MDE’s Back River monitoring and compliance information and submit odor complaints through the state’s reporting channels.
Why the plant matters
Back River is in Dundalk and is owned and operated by Baltimore City. MDE says it processes an average of about 100 million gallons of sewage each day and serves approximately 1.3 million people across the Baltimore region. Baltimore County owns local pipes serving county residents, while the state remains the environmental regulator.
What happens next
The immediate focus is on operational controls, continued monitoring and investigation of reported odors. The next major milestone is the third-party engineering report, expected by the end of 2026 or early January 2027. Its findings are expected to inform the city’s broader abatement decisions.
For now, residents and nearby businesses should distinguish between work already underway and recommendations that remain pending. MDE’s Back River pages provide monitoring data, compliance updates and complaint guidance as the city and state continue their review.
Sources
- Maryland Department of the Environment: Back River Air Monitoring
- CBS Baltimore: Baltimore County residents say Back River plant odor is disrupting their lives
- WBAL Baltimore: Baltimore Back River plant odor complaints grow
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