Water Quality Monitoring
The purpose of the beach monitoring program is to protect the public health and assure that the beach water is safe for recreational activities and to minimize the likelihood of water-borne disease outbreaks on Madison beaches.
The PHMDC (formerly Madison Department of Public Health [MDPH]) laboratory has been testing beach water quality for over 50 years. In the 1950's, when this testing was first established, the most common source of enteric bacteria was untreated raw sewage. The preferred, easy-to-find bacteria was fecal coliform. Since then, fecal streptococcus, fecal enterococcus, and E.coli have also been used. If test results showed that bacterial populations exceed acceptable levels, a beach was closed and warning signs were posted in order to protect the health of the public. When further sampling confirmed that bacteria levels dropped to acceptable levels, the beach was reopened.
Each month the Public Health-Madison and Dane County (PHMDC) Laboratory monitors Lakes Waubesa, Wingra, Monona, Mendota, and Kegonsa for chemicals that might be present in the water. Some of the things lab analyzes in the water include chloride, fluoride, nitrite, nitrate and sodium. Water samples are also tested less frequently for other contaminants, including arsenic, cadmium, calcium, mercury, selenium, lead, and zinc.
Today, the PHMDC Laboratory continues to test for fecal coliform and E. coli densities. From May through September, the Public Health-Madison and Dane County Laboratory tests 13 City of Madison and 2 Dane County beaches for bacteria, and now also screens for algal toxins such as microcystin and cylindrospermopsin. If in excess of acceptable levels, any of these contaminants may warrant closing the beach until levels have subsided. When a beach is closed for any reason, warning signs are still posted to inform citizens of the possible risks associated with swimming in that area.
Occasionally, microbiological contaminants, including illness-causing enteric pathogens and nuisance blue-green algae (cyanobacteria), concentrate on the near-shore areas during the peak recreational season.
The Public Health Department monitors beaches to:
To achieve these goals, we monitor to detect and evaluate the occurrence of potential problems and to assess health threats.
Because testing for enteric pathogens (bacteria, viruses, parasites) is time-consuming, difficult and expensive, PHMDC uses easily measurable bacteria that indicate fecal contamination and potential presence of human pathogens to evaluate a possible risk. Traditional indicator organisms (E.coli and fecal coliform) are currently used in our laboratory.
During the swimming season, we survey beach sites for cyanobacteria proliferation. Because a bloom situation (and possibly also the toxicity of a bloom) may change rapidly and vary widely in space, surveillance needs to be well timed and prompt to be adequate. Consequently, monitoring frequency is intensified during active bloom situations. Lifeguards notify us of the apparent water quality during the day, which may result in water sampling. Field samplers' observations or citizens' calls may also trigger sampling. Water samples are evaluated qualitatively for the presence and abundance of the cyanobacteria species of concern. We may also perform a screening test for toxins, such as microcystin or cylindrospermopsin. This type of assessment allows us to make near real-time management decisions. The results of the evaluation dictate whether any intervention, such as beach closure is appropriate.