A series of four cascading basins were installed at Hambleton Creek Farm in Chestertown, Maryland to treat agricultural stormwater from a 45.4 ha watershed. The basins drain into Hambleton Creek, a tributary of the Chesapeake Bay. The basin system was monitored for 22 months from July 2013 to April 2015 for concentrations and mass loads of suspended sediments, phosphorous and nitrogen. Over the duration of the study, 27 storm events were successfully sampled and tested. During this time, the basin system provided statistically significant reductions of sediments, total phosphorus and total nitrogen mass loads. The total volume reduction exhibited by the system was 56%; volume reduction appears to be the main mechanism of removal for suspended sediments, phosphorus, and nitrogen. Total mass reductions based on an input/output approach for suspended solids, total phosphorus and total nitrogen were 65%, 59%, and 64%, respectively.