By SHELLEY TOPP
Users of the Ashley Rakahuri Regional Park have voiced their disappointment over the presence of toxic algae in the river. People should be able to swim in all our rivers, streams and lakes, they say.
Their comments came after Environment Canterbury, the Canterbury District Health Board and the Waimakariri District Council issued joint warnings last week that benthic cyanobacteria had once again been found in two Waimakariri rivers, making them unsafe for swimming at the height of summer.
“People and animals should avoid the Ashley Rakahuri River near the Rangiora-Loburn bridge and Otukaikino/Waimakariri confluence near State Highway and Main North Road bridges area until the warnings have been
lifted,” the warnings said.
There are also other access points along the river that may have cyanobacteria present, the officials warned.
Notices have been posted warning people not to swim, and to keep their dogs out of the river and streams.
Brothers Jonathan and Malcolm Hawkes, of Rangiora, regularly cycle through the park on their mountainbikes.
They do not swim there but are disappointed to see it is again unsafe for bathers.
“It is a great shame people cannot swim in the river because it is a nice picnic area here,’ Jonathan says.
However, he has seen people swimming in the river, despite the warnings.
Two young Kiwi women, Michelle Williams and Sandra Stebler, who are travelling around New Zealand with Michelle’s dog, Nugget, were also disappointed.
“New Zealand should have clean rivers,” Michelle says. “It sucks that the river is unsafe to swim in.”
Bruce Coleman and his partner, Kim Raymond, both from Christchurch, visit the park to use the mountainbike tracks. They say it is a “lovely park with really nice mountain bike tracks”, but add it is not good enough that the river is not safe for swimming.
Environment Canterbury chief scientist Tim Davie says toxic algae grows during summer when river flows are often low and stable, and water temperatures increase.
“The Ashley River at the Rangiora-Loburn Bridge often experiences blooms (particularly after the Christmas/New Year break). However, some years they are more common than (in) others.”
It is likely that more blooms will occur in Canterbury as summer continues. But it is difficult to ascertain whether blooms are happening more often, he says.
Algal blooms can be toxic to humans and animals. They can lead to oxygen depletion and smelly, slimy waterways. The lack of oxygen kills freshwater species.
The presence of animals in or near waterways leads to faecal bacteria, which can be harmful to humans.