Hawke's Bay Regional Council environmental monitoring staff have noticed an increase in phormidium (blue-green algae) along the Tukituki River.
"We are concerned about the potential health risks for people and dogs as some reaches of the Tukituki now have 80-90% coverage of phormidium which can become toxic," says Anna Madarasz-Smith, senior environmental scientist.
Mrs Madarasz-Smith says that the settled weather, along with high temperatures, long days of light and lower flows have created perfect conditions for the algal growth.
"The affected reaches of the Tukituki we have noticed during our regular monitoring are around Tennents Road, Patangata and Horseshoe Bend (near Kahuraniki Road). However people need to look at the whole river bed as mats can lift and drift downstream."
With lower water flows in rivers and streams, 12 water take bans are in force in the catchment with only 5 locations still available to take water. On the Tukituki River itself five bans out of the seven are in force.