Sim, D.A, Townley, L.R., and Turner, J.V. (1996), Modifications to lake hydrology and chemistry due to stormwater discharge, in Wetlands for the Future, INTECOL's V International Wetlands Conference, Perth, 22-28 September, Programme and Abstracts, p.88.

Shenton Park Lake, Perth, Western Australia, is a urbanised wetland with a primary role as an infiltration basin for the recharge of stormwater . The lake displays a range of environmental management problems common to shallow wetlands of the Swan Coastal Plain, including eutrophication and low summer water levels. In this study, the flow dynamics and water balance of the lake-aquifer system were modelled using a triangular finite element model, AQUIFEM-N, to identify modifications to lake hydrology and chemistry and determine the potential of nutrient leaching to the groundwater. Stormwater discharge from the urban catchment was monitored using a doppler instrument, and groundwater fluctuations within the lake reserve were recorded by piezometers with automated dataloggers. The lake water balance was found to be dominated by the stormwater runoff component, so that the lake's flow-through regime was transformed during winter to a continuous recharge source to the aquifer. Stormwater was recognised as being the major source of phosphorus to the lake, while low concentrations of nitrogen in the runoff waters transformed the water body from hyper-eutrophic in nitrogen over summer to an oligotrophic status in winter. Concentration of nutrients via evaporation partly explained high levels of nitrogen in the lake over summer, but an analysis of flow regimes suggested that leaching of nitrogen from a former landfill site was also restricted to this season. It was concluded that stormwater recharge at the site had no detrimental effects on the quality of groundwater in the area, due principally to the low concentration of contaminants in the runoff waters and the function of the wetland as a large settling pond for the assimilation of heavy metals and nutrients. Modelling of this system has shown that transitions in the flow regime of the lake can occur within hours, where the water balance is dominated by a runoff or stormwater discharge event.