>Magister Scientiae - MSc / The water quality in many Cape Town Rivers and streams is a major challenge. Kuils River is subject to multiple land use impacts from upstream to downstream because of rapid urbanization in its catchment area. The main pollution sources are urban and industrial, organic matter from litter under the road-bridge, and golf course. However no systematic efforts have been made to evaluate and improve the health of the river in term of management. To assess impacts on water quality, this study was conducted from 4th September to 27th November 2012 in 5 selected sites in the upper reach of the Kuils river. The main aim was to compare the health of the river in 2012 with that found in 2005 using physical and chemical characteristics and the South Africa Scoring System (SASS). The statistical analysis showed a significant difference between and within sites. The water temperature, pH, dissolved oxygen concentration, total dissolved solids (TDS), and salinity were collected in situ by YSI 30 meter. To evaluate nutrient (nitrate and phosphorus) concentrations water samples were analyzed at UWC laboratory using spectrophotometer. In addition human activities, basic conditions (7.13 to 8.76), high total dissolved solids (416 to to 916.5 mg L¯¹) and salinity (0.31 to 0.71 mg L¯¹) concentrations were influenced by Malmesbury shales. Nitrate (0.1 to 3.1 mg L¯¹) and phosphorus (0.11 to 5.27 mg L¯¹) concentrations and the decrease in dissolved oxygen in November 2012 showed eutrophic conditions of the river. In the tributary site phosphorus (1.32 to 3.62 mg L¯¹) concentrations revealed hypertrophic condition compared to South Africa guideline. Macroinvertebrates sampled showed a total of 28 taxa grouped in 11 orders were sampled. Poor habitat diversity and water quality degradation were principal causes of low species diversity. The South Africa Score System version 5 (SASS5) and Average Score per Taxon (ASPT) indicated that the river is seriously impacted in 2012 compared to 2005 where water quality was in poor condition. The SASS and the ASPT scores were less than 50 and 4.2 at all sampling sites in most part of sampling period.

Freshwater in adequate supply and quality is vital to life on Earth; however, land-based activities such as development, agriculture, mining and industry, and their associated contaminants, pose a major threat to the quality of freshwater water resources and health of aquatic ecosystems. The upper uMngeni catchment draining into Midmar Dam is a strategically significant water resource, supplying clean drinking water to the eThekwini, uMgungundlovu and Msunduzi municipalities. The quality of this resource is under threat from current land-based activities such as Mpophomeni settlement and agriculture and emerging threats in the form of the Khayalisha social housing project. Monitoring sites were established in varying land use types in three sub-catchments of the upper uMngeni, to assess water quality and ecosystem health impacts of current land uses on Midmar Dam. A suite of physical, chemical and biological water parameters were sampled in conjunction with SASS5 bio-monitoring to assess the associated impacts. Water quality and ecological condition were highest in forested land use and upstream of Mpophomeni where natural land cover and sparse settlement occurred. Marked declines in water quality and ecological condition were observed at areas under commercial agriculture, indicated predominantly by rises in nutrient concentrations and declines in the SASS5 indices. The most notable declines in water quality and ecological condition were observed at sites downstream of Mpophomeni settlement as a result of severe sewage contamination, indicated by high E. coli counts. Nutrient concentrations downstream of Mpophomeni settlement ranged from mesotrophic to hypertrophic, with nitrogen to phosphorus ratios indicative of nitrogen limitation. Ecological condition remained in the ‘seriously/critically modified’ category over the study period. Nutrient loads produced by Mpophomeni are the highest of all the land uses, followed by that of commercial agriculture; both should be viewed as a concern, more so when viewed in terms of their compound effect on Midmar Dam water quality. Current water quality draining the commissioned Khayalisha social housing development area is good and although not natural, is of no contamination concern to Midmar Dam. Results indicate that with current land use activities, urban development and agriculture pose a potential threat to the quality of Midmar Dam resource and that further development in the form of the Khayalisha social housing project may replicate impacts already prevailing in Mpophomeni, whereby a principle water resource may be threatened by eutrophication. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.