GLEN ARM WASTEWATER TREATMENT PLANT (FORMERLY GRUMMAN WWTP)

Glen Arm plant's ammonia violations repeat on an already-impaired creek

The Glen Arm Wastewater Treatment Plant, which discharges directly into Long Green Creek in Baltimore County, has exceeded its permitted ammonia limit twice in the past year: by 368% last September and by 340% again this past March. Two exceedances roughly two quarters apart point toward a recurring problem at the plant rather than a single upset event. Ammonia at these concentrations is directly toxic to fish and aquatic invertebrates, and as it breaks down in the water column it also draws down dissolved oxygen. That matters here because Long Green Creek is already listed as impaired and is awaiting a federal cleanup plan, meaning it has little buffer left to absorb additional oxygen stress. It's worth being clear about what isn't known. No downstream ammonia, nutrient, or dissolved-oxygen data could be pulled this session to confirm whether these exceedances actually shifted conditions in the creek itself. What's documented is a permit violation on paper, not yet a measured ecological effect in the water. Still, it's a useful reminder of how many pressure points feed into the oxygen swings this creek experiences through the summer heat, especially given that it sits within a watershed of roughly 160 permitted dischargers, of which current EPA compliance records flag 60 as being in significant non-compliance right now.