Horizons Regional Council is continuing to warn users of Lakes Wiritoa to be cautious due to blue-green algal blooms.
However, algae growth has dropped considerably at Dudding Lake in the past week, making that lake safe for recreational users.
Barry Gilliland from Horizons said warning signs were not considered necessary at Lake Wiritoa because, while there were high levels of algae in the lake it was not toxic.
"We'd ask people to please heed the usual advice to mix the surface water up by doing a few circuits of the lake in a power boat before undertaking activities like water skiing. Although no surface scums were observed when sampling, this simply a precaution to mix any algae into more of the lake water if it is concentrated near the surface."
Warning signs are still up at Virginia Lake and Westmere Lake, asking people to wash their hands if they came into contact with the water. The signs were erected in mid-December after algal blooms were detected there.
Meanwhile, the water at both Castlecliff and Kai Iwi beaches continue to be safe for swimming. Caution should be taken when swimming in the Whanganui River at the city bridge, and the Mowhanau Stream at Kai Iwi.