Beach water quality : a comprehensive analysis of the pathogenic pollution of the Durban coastline.

Abstract

South Africa's beaches have many local and international visitors. Various recreational activities occur along the Durban coastline, especially during the holiday seasons. Beach water quality is negatively affected by pathogenic pollution which enters coastal water via stormwater and river discharges. Poor water quality jeopardises public health and has an adverse effect on tourism and the economy. The focus of this research is pathogenic pollution of Durban‟s coastal waters. In an attempt to understand the changes and establish any trends in pathogenic water quality conditions over the past decade, a critical assessment and statistical review of the historical water quality conditions of the Durban beaches has been done. This involves a general statistical analysis and water quality classification according to the new South African Water Quality Guidelines. Statistical parameters considered include arithmetic mean, standard deviation, geometric mean, and percentiles. A total of 42 beaches were analysed. Beaches were grouped into 4 sections: Northern, City, Bluff, and Southern. Water quality data for E.coli and Enterococcus were analysed from 2003 to 2013. The highest concentrations of both bacteria occurred in summer and autumn most often. Generally the average levels of both bacteria have either remained consistent or increased. Large standard deviations noted indicate variability in pollution as they represent a large spread of data from the average pollution values. Geometric mean comparisons show that Enterococcus levels were generally higher than E.coli, but both bacteria follow same patterns. Classification of water quality conditions shows that water quality has deteriorated as the frequency of poor water quality has increased. Water quality is classified as poor more frequently based on Enterococcus when compared to E.coli. However, higher levels of E.coli are allowed than Enterococcus as per the guidelines. Beaches located near rivers and stormwater outfalls are adversely affected and are shown to exhibit poorer water quality conditions. A case study was completed involving the analysis of the beach water quality data for 2009 to 2013 to determine the possible eligibility of Durban‟s beaches to receive the Blue Flag Award. Based on the microbiological water quality, it is unlikely that Durban will be a “Blue Flag coastline” in the immediate future. Most beaches have not managed to consistently meet the criteria for both E.coli and Enterococcus. As of October 2014, 7 beaches had pilot status.