Swimmers and recreational water users are being advised to stay out of two Taranaki waterways after high counts of eColi were measured.
The Waiwhakaiho River at Lake Rotomanu and Te Henui Stream both have elevated levels of the bacterium.
Contact with eColi contaminated water can cause stomach cramps, diarrohea, nausea, vomiting, and low-grade fever.
The Taranaki Regional Council has also warned there was a risk to dogs from algae mats in the Waiwhakaiho River at Merrilands Domain, and below Lake Rotomanu and the Kaukoponui River at Beach Domain.