Which South Canterbury rivers are safe to swim in this summer should soon be a lot clearer, with ECan about to start water testing throughout the region.
ECan staff and three university students will carry out weekly tests at 51 freshwater and 45 coastal swimming spots from Kaikoura to the Waitaki over summer.
At present, the highest water quality for swimming at monitored South Canterbury sites is at Lake Opuha dam's boat ramp or recreation reserve and the Timaru Yacht Club.
Staff will also be on the lookout for cyanobacteria mats (blue-green algae) such as Phormidium, which can produce toxins dangerous to humans, stock and dogs. There is a greater risk of potentially toxic cyanobacteria mats occurring during periods of low river flow and warm temperatures. Black cyanobacteria mats should also be avoided. They can be attractive to dogs due to their odour and can cause serious illness or death if licked or ingested.
The results are updated weekly on the Environment Canterbury website: maps.ecan.govt.nz/Water Quality.
While Lake Opuha and the yacht club offer the best options, many other sites have been graded as good, with a green spot marking their location on the website map.
At sites where cyanobacteria mats are found, ECan staff will carry out a detailed survey. The results will be compared to national guidelines and if trigger values are exceeded a warning will be issued for the site and posted on: ecan.govt.nz/services/online-services/monitoring/swimming-water-quality/Pages/river-warnings.aspx.
Warning signs will be erected at the site and there will also be signs telling people what to look out for in areas where cyanobacteria mats have been found in the past.
- © Fairfax NZ News