Glossary of beach water quality terms

Do you need a little help? Find an explanation of some of our less common terms.

Algae: quite simple chlorophyll-bearing plants which are capable of photosynthesis. They occur in the aquatic environment, and can be microscopic in size.

Algal Bloom: discolouration of the water environments due to a change in species composition and abundance of marine and estuarine microalgae.

Amplification: changing a sewage treatment plant, so it can treat more sewage per day.

Bacteria: group of diverse, singled celled, microscopic organisms living in nearly all land and water habitats. Specific types are found living safely with humans and animals and some have the potential to cause disease. Bacteria can also be used to show the possible presence of sewage in stormwater and receiving waters (see below). (Also see enterococci).

Beach Suitability Grade (BSG): the grade is a long-term assessment of the suitability of a swimming location for swimming and is based on a combination of Sanitary Inspection and water quality measurements gathered over previous years. Swimming locations are graded Very Good, Good, Fair, Poor or Very Poor.

Blue-green algae: a photosynthetic bacteria which can occur in fresh and salt water and produces oxygen. Some can produce substances toxic to animals. The blue-green is caused by phycocyanin pigments. This algae includes Anabaena and Microcystis spp. High concentrations affect the suitability of water for recreation and drinking.

Catchment: the area that drains surface runoff and groundwater supply from rainfall into a watercourse or urban stormwater drainage system.

Colony forming unit (CFU): a micro-organism propagule (spore or cell) from which a colony has grown. For purposes of analysis, one cfu represents one viable organism. Typically, data on bacteria is reported as the number of these colonies in 100 millilitres of sample water.

Contaminant: any substance, chemical, or micro-organism that makes a medium (water) less suitable for a specific purpose.

Criteria: standards based on the analysis of scientific data that provide guidelines for the appropriate use of water.

Density (e.g. enterococci or faecal coliform): the amount of these indicator bacteria present in a waterbody. The higher the bacterial density, the higher the number of CFUs (see above) that will be found per 100 millilitres, and the greater the contamination.

Diarrhoea: a common symptom of gastrointestinal disease characterised by fluid consistency of the stools.

Enterococci: bacteria of the genus Enterococcus that may be used to find out how much faecal matter is present in recreational waters. The Enterococcus group is a sub-group of faecal streptococci. It is differentiated from other faecal streptococci by growth at higher temperatures and salt concentrations in the laboratory, and the ability to survive in marine waters under conditions that are unfavourable for most other faecal micro-organisms.

Epidemiology: the branch of medicine which deals with the incidence, distribution, and possible control of diseases and other factors relating to health.

Estuary: A partially enclosed coastal water body open to the ocean, characterised by tidal effects and the mixing of fresh and marine water.

Faecal bacteria: usually taken to mean faecal coliforms and enterococci. These bacteria are used as indicators of sewage pollution as they are present in the faeces of virtually all warm-blooded animals. Their presence in water indicates that faecal matter is present and that pathogens also may be present.

Gastrointestinal: Originating in the stomach and intestines of animals.

Indicator micro-organisms: bacteria (generally faecal coliforms and/or enterococci) that indicate the amount of faecal contamination in waterways. Indicators are generally used to monitor recreational water quality, because searching for specific micro-organisms that cause disease, such as viruses, is both difficult and costly.

Infection: to acquire viruses, bacteria or fungi in animal or plant tissues.

Microbial assessment category (MAC): the category is determined from the 95th percentile of a dataset of at least 100 enterococci data points. The 4 categories (A to D) relate to levels of risk of illness determined from key epidemiological studies. The National Health and Medical Research Council recommend the MAC be calculated from a rolling 5 year dataset, with at least 20 samples collected each year during the swimming season. 

NHMRC: the National Health and Medical Research Council. An independent statutory agency that oversees national public health and medical issues. On the basis of current research, the organisation produces exposure guidelines intended to protect public health.

Pathogens: disease causing organisms such as bacteria, viruses and fungi, which can cause disease in plants and animals. Pathogens can be present in high concentrations in municipal sewage, industrial and other types of discharges.

Plume: a stream of water containing a high concentration of suspended materials and/or pollutants (see below) entering a waterway.

Pollutants: chemical or biological substances discharged into bodies of water that are potentially damaging to the environment.

Primary contact recreation: this is recreational use of waters that involves a person entering the water or submerging. It includes activities such as swimming, diving, water skiing and surfing.

Primary sewage treatment: this is the physical treatment of sewage, designed to remove solids (sludge) via settling, and floatable solids such as oil, fats and grease by first screening the effluent and then putting it into ponds.

Quality assurance/quality control (QA/QC): procedures and checks used to ensure environmental sampling and analysis programs get accurate and reliable results.

Receiving water: this is the water body into which effluent flows. For example, sewage treatment plants or stormwater systems release water into natural waterways such as rivers, estuaries and oceans.

Salinity: a measure of how much dissolved salt is in water. It can be estimated by measuring how well the water conducts electricity.

Sanitary Inspection Category (SIC): the Sanitary Inspection Category is determined from a sanitary inspection of a swimming location. The sanitary inspection identifies potential pollution sources, assesses the risk posed by each and then determines the overall risk at the swimming site (the SIC), which is categorised as Very Low, Low, Moderate, High or Very High.

Secondary contact recreation: recreational use of waters that involves some direct contact with water, but the probability of swallowing water is unlikely. It includes activities such as paddling, wading, boating and fishing.

Secondary sewage treatment: biological and/or chemical treatment of sewage designed to remove most organic matter and solids through several possible processes by using bacteria that doesn’t require oxygen to grow (anaerobic), chemicals and settling ponds.

Sewage treatment plant (STP): the site where household, commercial and industrial sewage meet for treatment via the sewerage system. Sewage is treated at an STP to either primary, secondary or tertiary level before being discharged as effluent to receiving waters (see above). Also known as wastewater treatment works.

Sterilisation: the process of destroying all living micro-organisms.

Stormwater: any surface water runoff resulting from rainfall can be termed stormwater. In undeveloped catchments (see above), stormwater can be of high quality and captured for drinking water. In urban areas, stormwater is likely to contain pollution and be of lower quality.

Tertiary sewage treatment: physical and chemical treatment of sewage, designed to improve secondary treated sewage by removing fine suspended solids, nutrients and pathogens (by disinfection). Treatment to a tertiary level typically involves a combination of filtration methods, chemical additives and ponding.

Tidal flushing: the process by which water in an estuary or river is replaced with water from the ocean due to the flow of water caused by the tides.

Toxicant: an agent or material capable of producing a negative response (effect) in a biological system (e.g. a person), seriously injuring structure or function or causing death.