People are being warned to stay out of a lake near Hamilton after an increase in the levels of a dangerous algae.
Waikato District Health Board issued the health warning today for Lake Rotokauri.
The warning was made after cyanobacteria levels rose, the board's medical officer of health Dr Richard Vipond said.
Existing health warnings also remained in place for Ngaroto, Kainui, Whangape and Waikare lakes, Vipond said.
Puketirini, Te Koo utu, Hakanoa, and Waahi lakes, which are also regularly tested by Waikato Regional Council, currently remained below the warning level for cyanobacteria.