Assessing the Yield and Load of Contaminants with Stream Order: Would Policy Requiring Livestock to Be Fenced Out of High-Order Streams Decrease Catchment Contaminant Loads?

This paper won the JEQ Best Paper Award 2019. Concentration and flow data for 1998 to 2009 were used to calculate catchment load and yields of nitrogen (N) and phosphorus (P) species, suspended sediment, and Escherichia coli at 728 water quality monitoring sites. On average, the yields of all contaminants increased with increasing stream order in catchments dominated by agriculture. Loads from low-order small streams exempt from potential fencing regulations accounted for an average of 77% of the national load (varying from 73% for total N to 84% for dissolved reactive P). This means that to substantially reduce contaminant losses, other mitigations should be investigated in small streams.