The Whangamarino Wetland, in northern Waikato, is an internationally recognised mosaic of bogs, swamps and fens covering 7000 hectares around the Whangamarino and Maramarua Rivers. This Ramsar Convention site is the second-largest wetland complex of this type in the North Island and home to a number of rare species including the swamp helmet orchid, black mudfish and the Australasian bittern.
The weir, constructed from gabion rock baskets, helps maintain the wetland ecosystem by controlling the flow of water. The weir is visible in summer and autumn but is largely submerged in winter and spring. It is designed to keep the water in the wetland at a minimum summer flow level to avoid the wetland drying out completely.
Several wire mesh baskets have been severed, compromising the weir’s structural integrity. A channel has been created allowing water to flow through – undermining the purpose of the weir at this time of year.
DOC’s Waikato District Operations Manager Ray Scrimgeour says repairing the weir before the wettest of the winter weather emerges – submerging the weir – is vital
“In its current state, with no repair, it’s likely the weir would completely disintegrate and seriously impact the habitat of the wildlife across the wider wetland,” Ray Scrimgeour says.
“DOC is one of a number of agencies and stakeholders to have invested significant time and resource into Whangamarino, and we cannot allow that investment and effort to be washed away or dried out because of the damage to this weir.”
The repair work will be carried out following strict health and safety protocols at COVID-19 Alert Level 3 and is expected to take two days. The work will be done by a two-man crew and will be visible from nearby roads and properties.
Ray Scrimgeour says the damage to the weir has been reported to New Zealand Police, and DOC would welcome any information from the community about how and when the baskets were severed.