A Streamlined Methodology for Identifying Point-Source Inputs from Rural and Agricultural Sources

Rural and agricultural runoff continues to pose a threat to water quality and human health despite a plethora of research identifying likely causes. Large livestock operations and leaking septic systems have proven to be significant sources of both nutrients and bacteria in the form of algal blooms and antibiotic-resistant Escherichia coli . These impacts are often witnessed on a watershed scale. Implementing remedies is complicated, as livestock operations are defined as point-source facilities under the USA Clean Water Act (CWA) but regulated as non-point-source entities under a NPDES CAFO general permit. Non-point-source pollutant assessment of watersheds involves a wide array of sampling parameters that focus primarily on impacts after-the-fact and lack regulatory teeth. This watershed management approach is not sustainable, as evidenced by the continual degradation of our rural watersheds. This study lays out streamlined methods and techniques incorporating focused parameters that can infer point-source pollutant pathways even in already impaired waterways. We applied this methodology to the Pine River Watershed in central Lower Michigan after the appearance of an algal bloom downstream from several potential nutrient inputs. Findings show that the application of these unique methods and techniques results in the successful identification of point-source inputs. These methods are inexpensive and demand few resources, and hence they are easily reproduced and replicated. Therefore, by regulating large livestock operations as point-source discharge entities, it is possible for local communities, educational institutions, and regulatory agencies to identify likely pollutant sources in a way that promotes higher water quality and long-term sustainability.