More rivers affected by toxic algae

Piers Fuller Reporter from News of Wairarapa

Toxic algae is quickly intensifying throughout the region, with all monitored rivers reaching health alert levels and Wairarapa’s Waipoua River remaining hazardous for swimmers.

Greater Wellington’s Otaki, Waikanae, Hutt, Ruamahanga and Waingawa river monitoring sites have exceeded the 20 per cent alert threshold, and the Waipoua River is above the 50 per cent “no swimming” line. Detached mats, which are particularly hazardous for dogs, have been seen in all rivers.
It is highly likely the same conditions apply to many non-monitored rivers in other parts of the region, so it would be useful for people visiting rivers to know what toxic algae looks like so that it can be avoided.
“Our message is clear. People should stay out of the Waipoua River and remain vigilant in other rivers,” says Greater Wellington Senior Environmental Scientist Dr Mark Heath.
“Levels are expected to increase, with hot dry conditions forecast for much of the region throughout next week.

Specific site warnings are:

• Waingawa River, warning for south road site

• Ruamahanga River, warning for Morrisons bush site

• Waipoua River, warning extends from Paierau Road to confluence with the Ruamahanga

Toxic algae grows on submerged river stones, presenting with a shiny brown/dark green to violet coating. It can also become unstable and detach, floating to the surface forming small brown/black mats at the water’s edge.

Given conditions quickly change, people should be remain vigilant around rivers and streams throughout the region. This is the prime season for toxic algae, so look out for algae covering rocks and for detached mats in the water and lining riverbanks. If in doubt, stay out of the water and keep a close eye on children and dogs,
Before you swim, stay safe by finding out about toxic algae at www.gw.govt.nz....
For more information on where it is safe to swim, go to: www.lawa.org.nz...