Algal bloom in Tukituki River at Walker Road
Hawke's Bay
Health New Zealand | Te Whatu Ora has issued a health warning for the Tukituki River at Walker Road in Central Hawke’s Bay.
The warning follows the finding of potentially dangerous levels of toxic algae (Microcoleus *previously referred to as benthic cyanobacteria*) at this location by Hawke’s Bay Regional Council as part of its monitoring programme.
People should avoid swimming in the area, and animals, particularly dogs, should not be allowed near the water until the health warning has been lifted.
Dr Nicholas Jones, Medical Officer of Health for the National Public Health Service in Hawke’s Bay, says the algae looks like dark brown or black mats and can produce toxins harmful to people and animals.
“Exposure 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, also let your doctor know if you’ve had contact with dark brown/black algal mats or water in this area”, Dr Jones says.
There are also other access points along the Tukituki that may have the algae present. As we move into the hot summer months, people are advised to treat every low-flowing river cautiously by checking for the presence of the algal mats and avoiding contact.
Before swimming at public waterways this summer, people can also check Land Air Water Aotearoa (LAWA) to see the latest water quality information for public swimming spots near them.
Land Air Water Aotearoa (LAWA)external link
Pets that show signs of illness after coming into contact with algal mats should be taken to a vet immediately.
People and animals should remain out of the waterways until the warnings have been lifted.
Hawke’s Bay Regional Council is monitoring the sites, and the public will be advised of any changes in water quality.
Facts about microcoleus
- Appears as dark brown/black mats attached to rocks along the riverbed.
- A low cover of the algae can occur naturally but can increase rapidly during warmer months. Algal blooms are influenced by a combination of available nutrients in the water and sediments (such as nitrogen and phosphorus), a sustained period of low and stable flows, and favourable weather conditions (for example, increased temperature, calm days).
- It often has a strong musty smell and algal toxin concentrations can vary over short periods.
- Although high river levels will remove the algal bloom, detached mats can accumulate along the shore and increase the risk of exposure to toxins.
- If a health warning is in place avoid contact with the water.
- Although district or city councils may place warning signs, these may not be seen at the numerous river access points, hence the need for people/dog-walkers to treat every low-flowing river cautiously.
For further details visit Land Air Water Aotearoa (LAWA).
Tukituki River — Land Air Water Aotearoa (LAWA)external link