There are several ways in which enterococcus bacteria can end up in swimming water. These possible sources of contamination have been assessed for each site both prior to sampling occurring (eg: are there septic systems in the vicinity?) and at the time of each sample being taken (eg: how many people are swimming at the site at the time or what was the rainfall prior to testing).
Wildlife: Wildlife may input faecal bacteria into waterbodies. Usually waterfowl are the main contributor.
Agriculture: Intensive agriculture can cause localised threats to water quality where proper runoff protocols do not exist. Livestock with unrestricted access to watercourses can also contribute.
Sewage: via mismanaged or untreated wastewater. In urban areas, sewage can end up in recreational waterbodies as a result of combined sewage overflows, leaks, misconnects, and aging infrastructure. Rural areas largely rely on septic systems to treat wastewater. Septic systems require sufficient space to groundwater tables and routine maintenance in order to properly treat wastewater.
Pets: Pet owners who do not pick up after their pets threaten water quality. One 10 cent-sized piece of dog waste contains 23 million faecal coliform bacteria.
Human shedding: Humans toileting in or adjacent to waterbodies or washing themselves in waterbodies.
Stormwater & Urban Runoff: Stormwater and urban runoff is the number one source of beach closures, and can make the effects of all of the above sources of pollution much worse. When towns and cities experience rain, this puts pressure on aging infrastructure systems. When the ground is saturated, septic systems essentially act as cesspools, so untreated water is released into the groundwater. Any pet, wildlife or agricultural waste is much more likely to get picked up by rain and drain into a nearby waterbody.
Low flows in creeks and rivers means that there will be higher concentrations if there is a contamination.