River health warnings

We monitor river sites regularly over the summer to check for bacteria (faecal contamination) and toxic algae.

Each river site is given a long-term grade prior to the summer monitoring season for suitability for swimming and recreation. The grade is based on the last five years of bacteria sampling. Sites that are not recommended for swimming because of their long-term grade are red on the Land Air Water Aotearoa (LAWA) website and signage should be in place at the site.

Temporary Health warnings are issued when a site is graded as good to swim but there is now an increased risk of cyanobacteria or faecal contamination. Advisory notes may be present but are not an official public health warning.

Toxic algae (cyanobacteria) can occur in any waterway, at any time, so it is important that you know what it looks like. Find out more about toxic algae and how you can protect yourself and your animals.

Faecal contamination poses a risk to health, it can cause gastrointestinal illnesses, respiratory diseases, and eye, ear, nose, throat and skin infections.

Find out more about our monitoring programme.

Temporary health warnings

Toxic algae (benthic cyanobacteria) – multiple sites

Current river warnings

Water testing indicates moderate to high cover of toxic algae (benthic cyanobacteria) at these locations:

  • Conway River at Inland Road
  • Temuka River at SH1 Bridge
  • Entire Opihi River Catchment (the Opihi River and its tributaries) including: Saleyards Bridge, Raincliff Bridge, SH1 Bridge, Grassy Banks and SH79 Road Bridge
  • Hae Hae Te Moana River
  • Waihi River - upstream of Wilson Street Bridge in Geraldine

People should avoid these areas, and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted.

Other access points along these rivers may have benthic cyanobacteria present. People are advised to treat every low-flowing river cautiously, check for the presence of benthic cyanobacteria and avoid contact.

Fish and shellfish can concentrate toxins and their consumption should be avoided. If fish are eaten, remove the gut and liver and wash in clean water. No one should drink the water from the rivers at any time. Boiling the water does not remove the toxin.

Exposure to cyanobacteria toxin may cause skin rashes, nausea, stomach cramps, tingling and numbness around the mouth and fingertips. If you experience any of these symptoms visit your doctor immediately and please let your doctor know if you have had contact with the lake water.

Animals that show signs of illness after coming into contact with algal mats or scums should be taken to a vet immediately.

We are monitoring the sites and the public will be advised of any changes in water quality.