Summer scholarship with Wendy Timms This project examined the quality of surface water and groundwater in the Quirindi-Gunnedah area of the Upper Namoi catchment in Australia's Murray-Darling Basin. While several studies have assessed salinity, this is the first project to examine a wide range of water quality parameters including nutrients and agricultural chemicals since the Liverpool Plains Water Quality project 1997/98. In addition, for the first time, many trace organic constituents related to human activity were assessed. Sampling was conducted in January 2012.Surface water salinity was relatively low as expected (<1500 cm-1, except Native Dog Gully), within Namoi CMA salinity targets. In contrast to most sample sites in the Mooki catchment, Native Dog Gully demonstrated salinity, sodium and chloride measurements that far exceeded all crop and drinking water salinity guidelines. However, this is partially mitigated by the negligible discharge, although this area remains a salinity hotspot. The surface water salt load calculated for 2011, 128600 tonnes/year, was slightly lower than that measured in 1998, 146000 tonnes/year. This negates predictions for an increase to 305,000 in 2020 (Beale et al. 1998).However, groundwater salinity was found at levels above or approaching the upper limit of the Namoi CMA guideline for irrigation water, highlighting a gradual increase in groundwater salinity at some sites outlined by Timms et al. 2009.Trace organics of anthropogenic origin were widely detected in both surface and groundwater, including pharmaceuticals, cosmetics and caffeine. Caffeine was the most widely detected organic and while most organics were not of concerning concentrations, their widespread presence raises questions as to the persistence of some human excretions in environmental waters. The only guideline exceeded was for atrazine and simazine with respect to the precautionary aquatic ecosystem protection guideline (99% of ecosystem inhabitants). However results did comply with crop and drinking guidelines.The calculated hydraulic gradient from surface to groundwater values, suggests that rivers contribute a portion of the recharge to groundwater, although the magnitude of this remains undetermined. The stable isotope ratio of most groundwater samples was depleted relative to modern rainfall, suggesting primary recharge of those aquifers was from a wetter climate, or recharged during high intensity rainfall events, though the age of the water was not determined. Liquid Chromatography - Organic Carbon Detection (LC-OCD) a new technique for analysing dissolved organic carbon (DOC) in water, showed a clear differentiation between surface and groundwater. This is the first groundwater LC-OCD analysis in this area and presents scope for further study.