Isogram showing space/time classification of the surf zone at 29 sampling stations between the Umgeni River mouth (Station 1) and Isipingo (Station 26) The horizontal axis shows the stations approximately distanced and the vertical axis shows years. Red shaded Class IV areas are heavily polluted, while lightly shaded blue areas indicated as Class I are not seriously affected. The level of pollution is determined from the sum of a number of indicator tests such as levels of E. coli, Salmonellae, Shigellae, Staphylocci and parasites. (From CSIR, 1996)