Lake Taupo has been plagued by a toxic algae bloom which resulted in the cancellation of the swimming leg of the Taupo Ironman.
And with more hot, calm weather forecast, the bloom is set to continue.
Dr Eloise Ryan, senior water scientist for Waikato Regional Council joins RadioLIVE's Ryan Bridge to establish how long it will last, what caused it, and what effect it will have on fish in the lake.
[The algae bloom] is quite extensive.
At the moment experts aren't entirely sure if the algae bloom is serious or if it's just a non-toxic algal mat, but tests are ongoing.
As a precaution, people are being urged to avoid popular swimming spots where the algae is in bloom.
Listen to the full interview with Dr Eloise Ryan above.
Your Sunday with Ryan Bridge, 10am-2pm on RadioLIVE and streaming live to the rova app on Android and iPhone.