EW and DoC target alligator weed in North Waikato.

Boaties and other water users are being reminded that Lake Whangape and the Te Onetea Stream in North Waikato have been declared as restricted places under the Biosecurity Act.

This action places substantial restrictions on lake users’ activities, as a measure to prevent the spread of alligator weed.

The declaration was made in March as part of efforts by Environment Waikato and the Department of Conservation to stop the pest plant alligator weed infesting the internationally significant Whangamarino wetlands.

EW and DoC have been controlling alligator weed at Lake Whangape since 2002. Despite EW’s efforts to remove the alligator weed, patches of it remain in the lake and some has become established on nearby private land, said biosecurity officer Wendy Mead.

Recently alligator weed has also been found at Te Onetea Stream, which flows out of the lake, Mrs Mead said.

“This is a major concern as Te Onetea Stream flows into Lake Waikare and from there it is only a hop-step-and-jump to the internationally significant Whangamarino wetland, home to many rare plants which could be threatened by alligator weed.”

Mrs Mead said that it was essential to stop alligator weed spreading to Whangamarino to protect the wetland environment.

“While our eradication programme will go a long way towards achieving this, there remains a risk alligator weed will be accidentally transferred from Lake Whangape or Te Onetea Stream by boaties or other users of these areas.”

The declaration of both these areas as restricted places under the Biosecurity Act placed strict conditions on the users of these areas, such as the banning of any net fishing without prior approval from DoC. The declaration also stipulates all boats, trailers, and fishing gear must be cleaned and free of any weed before leaving the area, Mrs Mead said.

Livestock grazing in the area adds to the problem. Cattle can cause the weed to break up which can contribute to weed spread further downstream, so grazing in the restricted area is also banned.

“We’ve had reports of some people not following these rules recently and we need to remind people about the restrictions that are in place.”

DoC biodiversity ranger Craig Purvis has spent considerable time talking with users of Lake Whangape about the risks of alligator weed. “Until now we have relied on the goodwill of users to make sure there is no risk of accidental spread of alligator weed,” said Mr Purvis.

“However, it appeared a few people are persisting in using nets without approval, which is why the formal restriction was put in earlier this year. The public also needs to remember that Lake Whangape is a DoC wildlife reserve, meaning commercial fishing is not permitted.”