2009 BES Annual Meeting Presentation and Poster Abstracts
Effects of long term sewage outfall disturbance on water quality and macroinvertebrate communities in the lower Jones Falls, Baltimore, MD: preliminary results
Co-Authors: Stanley J. Kemp
Abstract: Sewage contamination is one of the primary remaining anthropogenic impacts on the Jones Falls, which drains roughly the central third of Baltimore City. Leaking, aging storm and sewer infrastructure and combined sewage outfalls continue to release untreated sewage into the Jones Falls, especially during periods of rain. This study documents the effects of one of the oldest and largest sewage outfalls on the Jones Falls, located on Falls Road near the defunct Maryland and Pennsylvania RR depot. Two sites above and below the outfall were chosen for a comparative study of water quality and biota, which began in July 2009. Dissolved oxygen remained relatively high at all sites through summer thermal peaks. Nitrate, phosphate, and ammonia nitrogen have remained detectable throughout the study, though at low levels. Small increases in concentration have been periodically observed following rainfall. Benthic macroinvertebrate communities are dominated by tube dwelling Chironomidae (Diptera), net spinner Caddis Hydropsyche spp. (Trichoptera), small minnow mayflies Baetis spp. (Ephemeroptera), Isopoda (Asellus spp.), and Oligochaeta. These species are found at all sites. All species found in the samples exhibit high to moderate tolerance of pollution. The main difference between upstream and downstream sites is a much higher number and proportion of Oligochaetes downstream of the outfall, an indicator of organic pollution. Some rarer species of Trichoptera were not found below the outfall, as were Amphipoda. The sewage outfall has altered the benthic macroinvertebrate community, although water quality differences attributable to the sewage outfall are small to date.