Urban stormwater is a key pathway for pollutants entering the Derwent Estuary, largely via untreated discharges from natural rivulets and stormwater networks. To assess current conditions and long term trends, the Derwent Estuary Program undertook an estuary wide stormwater monitoring program between June 2024 and May 2025.

Thirty five sites across upper, middle, and lower catchments were sampled monthly, primarily under base flow conditions, consistent with monitoring conducted in 2002–2005 and 2010–2011. Water quality was assessed using indicators of sediment (total suspended solids and turbidity), nutrients (total nitrogen, total phosphorus, and dissolved inorganic nitrogen), and faecal contamination (Enterococci and Escherichia coli). Sediment related pollutants were the most consistently elevated parameters, particularly in developing and agriculturally influenced catchments such as Risdon Creek, Cove Creek, and Faggs Creek. 

Nutrient concentrations exceeded guideline values (EPA Tasmania, 2021) at most sites, whilst faecal bacteria showed strong urban gradients, with highest levels at lower catchment sites. Upper catchments with stable land use consistently demonstrated better water quality. Comparison with historical datasets indicates broad long term stability, with localised improvements and declines influenced by land use change and rainfall variability.