This study was initiated to investigate the impacts that Inter-Basin Transfers (IBTs) from the River Murray have on the Onkaparinga River and the River Torrens, but also to monitor the impact chlorine, that accompanies the transfer in the Torrens, has on the system. The study had four main components. First, a thorough survey of the Onkaparinga and Torrens rivers was conducted above and below the IBT discharge in April and May, 1999. Macroinvertebrates were used as biological monitors and water quality was measured. Samples were collected with a Boulton Suck Sampler. In the Onkaparinga, species richness and abundance did not change considerably downstream of the discharge, but community assemblage did. The Torrens presented an absence of species richness and abundance with only a few species dominating. These affects can be attributed to the IBT discharge and chlorine input.

The second component of the study involved a rapid assessment of the Onkaparinga and Torrens rivers using four selected representative taxa, and monitoring the abundance and distributions of the chosen species. The Onkaparinga River's distribution of species can be directly attributed to the water quality conditions from the IBT with some species decreasing in abundance, while others became prevalent. The River Torrens distribution of species was absent downstream of the discharge. These results support the previous component of the impacts IBT and chlorine has on the systems.

The third component of this study was a LC₅₀ toxicity test using three concentrations on the four representative taxa from the rapid assessment. Mortalities were rapid in low and high concentrations. However, a range of sensitivities in the low treatment from 4-32 hours and 2-30 hours in the high treatment was present across three species. These mortalities corresponded closely to the distributions in the field research.

An unexplored and fourth factor of the study was the effects on primary producers and their influence on macroinvertebrate communities, providing areas for further research.