Bacteria counts at many of Wellington’s favourite swimming spots are keeping many would-be bathers high and dry following heavy rain earlier this week.
Over the summer period GWRC monitors 81 popular coastal and river swimming spots around the region on a weekly basis. Water samples from these sites are tested for E. coli (rivers) or enterococci (coastal sites) indicator bacteria. These bacteria indicate the risk of faecal contamination and the potential presence of harmful pathogens that can cause stomach upsets and other illnesses.
This week samples were taken on Tuesday after heavy rainfall throughout the region and as expected, show levels of bacteria that are above the guidelines for safe swimming.
The environmental scientist responsible for Council’s Recreational Water Quality Monitoring Programme, Summer Greenfield says it is common to see high bacteria counts in urban and farming areas following heavy rain.
“In urban areas rainwater collected from roofs, roads, car parks and other surfaces is piped directly into rivers, streams and the coast. During its travels, this stormwater picks up sediment, rubbish, contaminants, and dog and bird droppings. Sewer overflows can also occur in urban areas during wet weather.
“In rural areas, excess rainwater flows over the land and into nearby streams and rivers, picking up manure and other contaminants along the way.
Greater Wellington Regional Council and Regional Public Health advise people not to swim for up to 48 hours after heavy rain.
It is expected that bacteria counts at all sites will now have returned to safe levels following Tuesday’s rain. Follow up testing of high-count sites was done today and the results will be available early on Friday morning.
Weekly results are available at http://www.gw.govt.nz/on-the-beaches