Selected Water Quality and Flow Data From Minor Watersheds in the Blue Earth River Basin

As part of MRAP, selected minor watersheds were monitored in terms of water quality. This section of MRAP Volume II contains the results of this project. The study was conducted with one monitoring site used to evaluate total suspended solids, total phosphorus, and compare calculated storm event loadings, estimated storm events and loading, and watershed model predictions and loadings. Two additional sites were used to provide an evaluation of the loading and concentration changes that can take place within a storm event and over time. The continuous stage/flow records for the streams indicated run-off that peaks andthen returns to base flow conditions relatively quickly. Flow and loading estimates from a site in the Mountain Lake minor watershed indicated temporal variability associated with storm runoff. FLUX loading estimates indicated that over 50% of the flow and TSS, TP and SRP loading occurred during 16 storm events. Comparison of the FLUX estimated annual loadings with the MRAP level II land use predictions demonstrates that there is a potential for large differences in the numbers used for pollutant loadings in a watershed. The data from the two other minor watersheds demonstrated a change in flow and loading characteristics within a storm event. It is believed that these changes result from a change in the source of flow during a storm event hydrograph.