Proceedings of the 2020 Mississippi Water Resources Conference

Year: 2020 Authors: Ramirez Avila J.J., Chavarro-Chaux L., Ortega-Achury S., Richardson B., Czarnecki J., Schauwecker T.

Physicochemical and biological assessments of stream water quality and health have been advanced along a 0.9-km reach located within the MSU Dairy Unit in northeast Mississippi. The reach, a tributary of the Catalpa Creek, directly receives surface and concentrated (gullies) runoff from the upper 0.52-km² livestock drainage area production. A bi-weekly grab sampling of the reach advanced during the summer and fall 2019 evidenced poor water quality conditions of the, in average, 0.4-m depth stream baseflow. The observed water quality impairment along the reach is apparently driven by the presence of cattle in the fields and their direct access to the stream, the potential nutrient enrichment of the shallow water table (which maintains the baseflow level during the dry months of the year), and the supply of sediment from active streambanks along the main stream and tributary gullies. Measured nutrient concentrations (Total Nitrogen: 1.2-2.2 mg/l; Total Phosphorus: 0.27-0.72 mg/l; NO₃>0.3-0.78 mg/l; Total Kjeldahl Nitrogen: 0.72-1.82 mg/l) exceeded the standard nutrient criteria proposed for Mississippi. Critical levels of dissolved oxygen (DO) (1.6-5.0 mg/l) and water temperatures of up to 34.3°C, exceeding the standard of 32.2°C, were also monitored. The use of macroinveretebrates assessment as indicator of water quality, revealed little macroinvertebrate diversity and also evidenced poor water quality conditions along the reach. Samples were dominated by midge larvae (Family: Chironomidae) and aquatic worms (Subclass: Oligochaeta), both considered indicators of poor water quality when dominant. Other indicators of poor water quality conditions were green blooms and floating cyanobacteria, the latter mostly present along the deeper segments of the reach containing low DO. Monitoring will continue through the implementation of stream crossings and riparian buffers, practices expected to improve stream health and water quality conditions along the monitoring reach.