Concern rises over state of lagoon

An unidentified woman carrying a baby walks close to the potentially toxic scum that has been accumulating in places around the lower Tomahawk Lagoon and its outlet to Tomahawk Beach. Photo by Dan Hutchinson.
An unidentified woman carrying a baby walks close to the potentially toxic scum that has been accumulating in places around the lower Tomahawk Lagoon and its outlet to Tomahawk Beach. Photo by Dan Hutchinson.
Tomahawk residents say it is time to have a proper discussion about the state of their lagoon, given concerns over reduced water levels and toxic algae.

Last week, the Otago Regional Council issued a warning for users of Tomahawk Lagoon after finding a ''potentially toxic algal scum''.

''We are urging parents to keep their children out of the water and dog owners to do the same with their pets,'' council director of engineering, hazards and science Gavin Palmer said.

Resident Lloyd McGinty said he felt ''very in the dark'' about what was happening in the lagoon.

''I think the community as a whole would be interested in being a bit better informed on that, and on a wider scale the whole clean-up of that lagoon could be part of that discussion as well.''

Regional council technical committee chairman Bryan Scott said the council was trying to inform people of the danger in the first instance.

''In terms of any future issues or management issues or any community concerns, of course we should be listening. Any positive type of community dialogue would be a good thing.''

Editor of the Tomahawk newsletter ''Hawk Talk'' Danielle Culling said yesterday she was not aware the algal bloom had returned.

''It is a bit of a worry. My kids like to go and play down by the lagoon and the beach.''

Otago Peninsula Community Board deputy chairman Paul Pope said the ''algal issues'' were happening on a regular basis and they were of great concern to the community.

''Tomahawk is a unique area for the city and an area that is quite important for the wildlife, particularly the birdlife.''

The lagoon used to be ''deeper and cleaner'' and there even used to be a yacht club based at Tomahawk Lagoon, he said. Yachts can no longer use the lagoon because it is too shallow.

A change to the grate in the outlet tunnel under the road was thought to be responsible for silt becoming trapped in the lagoon, Mr McGinty said.

 

What's the cause?

Did I miss something here? What is causing the algae bloom? The article explains how the algae gets trapped but doesn't explain how it got there in the first place. Is it the heat, the agricultural run-off, the shallow depth, what is it?

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