Field monitoring of a stormwater treatment train had been underway between March 2014 and April 2015 at a commercial development located at Nambour, in Queensland's Sunshine Coast hinterland. The research was undertaken to evaluate the effectiveness of a Class 1 proprietary stormwater treatment system for removing total suspended solids and nutrients from runoff. Monitoring was undertaken on all events complying with the sampling protocol. The protocol was developed in collaboration with the University of the Sunshine Coast (USC), reflecting the Auckland Regional Council Proprietary Device Evaluation Protocol (PDEP) and United States Urban Stormwater Best Management Practice (BMP) Performance Monitoring Manual with some minor improvements reflecting local conditions. During the 18 month period, more than 59 rain events have occurred, of which 18 are complying with the protocol. The Efficiency Ratios (ER) observed for the treatment device are 83% TSS, 11% for TP and 23% TN. Dry weather sampling does not show conclusive evidence that pollutants are exported between storms or that concentrations increase significantly over time.