stream macroinvertebrates, waste water effluent, water pollution


In a previous study, Sager Creek, a small 1st-3rd order stream in northwest Arkansas was shown to be negatively impacted by urban land usage within the watershed, producing a stream that exhibited several indicators of urban stream syndrome. This included (1) physical disturbances: increases in impervious surfaces in the watershed, dams built across the stream, and alteration of the natural stream flow through the construction of retaining walls, (2) chemical disturbances: increases in electrical conductivity (EC) and total dissolved solids (TDS) as well as elevated PO4 levels (3) and biological disturbances: low populations of pollution intolerant macroinvertebrate species and high populations of pollution tolerant species. It could be hypothesized that these negative impacts could be mitigated by both biological and physiochemical remediation processes downstream from the effluent of the Siloam Springs Wastewater Treatment Plant (SSWTP), the most heavily effected of the previous study sites. A three-year investigation to test this hypothesis was completed. Utilizing physiochemical properties and biological assessments, four stream reaches, two in the previous research site and two downstream, were assessed for negative urban impact. Some acquired data supported the hypothesis that negative effects are mitigated downstream, particularly a lowering of EC and TDS levels and an increase in macroinvertebrate diversity. However, a larger amount of data, including mean water temperature, total water flow, pH, dissolved O2 and NO3 levels and mean Family-level Biotic Indices supported the null hypothesis that reaches above, at and, below the SSWTP were all equivalent in investigated physiochemical parameters and biological indicators.