Peat lakes: special ecosystems

Peat lakes: special ecosystemsRotopiko is today surrounded by 3km of predator-proof fencing.

The peat lakes of the Waipā district may seem small and insignificant when measured against lakes elsewhere in New Zealand, but they are, in fact, the biggest collection of such wetland anywhere in the country, and are of major significance.

There are 16 of them throughout the district, ranging in size from 4ha to the largest – Lake Ngāroto – at 70ha. They all contain fresh water, but in most cases it looks dark and dirty because of the tannins leached out from peat around and beneath the lakes.

They are also shallow, the deepest being only 9m, with most only 2m to 3m. Lake Ngāroto has an average depth of less than 2m. In every case they are surrounded by farmland or agricultural development, and constant drainage over the past half-century has seen water levels gradually lowered.

Some are now being protected by the Waipa District Council, working with the Department of Conservation and National Wetlands Trust.

Tony Roxburgh, Chairman of the National Wetlands Trust, says Lake Ngāroto now has a large protective margin around it, effectively doubling the lake’s total wetland area. There is an active programme to acquire land adjacent to such lakes to give them further protection.

“The ideal is to have lakes that are oligotrophic – very low in nutrients. But regrettably most of the peat lakes in the district are eutrophic or hypertrophic – becoming over-run with nutrients from surrounding farmland,” Mr Roxburgh says.

The lake with the most natural water and plant qualities is Lake Maratoto, a privately-owned lake west of State Highway 3 just south of the Hamilton Airport turnoff. It is not visible from the road and is only lake in the district covered by a QE II covenant.

Almost half of the lakes are privately owned. They include Pataka North and South, Mangahia, Henderson's Lake, Turnwald Pond, Milicich Lake, Maroto and Rotongata. Three others - Ngāroto, Mangakaware and Cameron are Crown-owned, designated as recreational reserves and managed by Council.

A further six lakes –  Rotopiko (also known as Serpentine), Rotomanuka, Ruatuna, Ngaroro-iti, Koromatua and Rotopataka – are also Crown-owned, desi​gnated as wildlife management reserves and managed by Department of Conservation. Rotopiko, located just south of Ōhaupō, is today a restored vegetation wetlands and wildlife sanctuary surrounded by 3km of predator-proof fencing.

Peat lakes: special ecosystems

Edited excerpts from the book 'Waipa Home of Champions: Celebrating 150 Years'. Written and produced by historians Richard Stowers and Kingsley Field.

Page reviewed: 17 Apr 2018 3:25pm