NIWA says its experimental trials aimed at freeing Rotorua’s lakes of blue-green algae are working.

Scientists have been working on putting phosphorus inactivation agents into Lake Rotoehu since autumn this year.

They’re aimed at combating a legacy of run offs from surrounding land of fertilisers and animal effluent.

An excess of nutrients feeds the growth of potentially toxic blue-green algae in some lakes.

NewstalkZB