Lakes' algae levels falling

Water quality in most Rotorua lakes is improving.

A report compiled by Environment Bay of Plenty scientists says the levels of algal bloom in most of the lakes are down but urges people to still check and clean their boats and trailers before and after using a lake.

Environment Bay of Plenty scientist Matt Bloxham said that overall, the outcome of the report was positive.

"There was both good and bad news in terms of lake quality. Algal blooms were down [but] ... we did find some new invasive weed in a couple of the lakes, which is of concern."

Two new species of weed were found in Lake Rotomahana. Environment Bay of Plenty scientist Paul Scholes said there was an excessive spread of weed. Lake Okataina was the other lake in which new weed was found. Mr Scholes said the Hornwort weed found there was "controlled". He said the water quality in most of Rotorua's lakes was "fairly stable".

There were also improvements in the level of blue-green algae in Lakes Rotorua and Rotoiti.

This season, two public health warnings were issued, whereas in previous years about four health warnings were issued each season.

Mr Scholes said Lake Okaro's water quality is showing improvement and this was the third continuous season of good results for the lake.

Lake Okataina was showing signs of degrading but Mr Scholes said it was stabilising. Tikitapu [Blue Lake] is also showing signs of degradation with the increase of phosphorous.

Phosphorous is an essential plant nutrient but in large quantities can encourage the growth of algal blooms.

- DAILY POST