Waikato Regional Council is working closely with local landowners and others on beefed up efforts to protect one of the region’s best functioning peat lakes, Lake Maratoto between Rukuhia and Ohaupo in Waipā district.
The council has recently undertaken a hydrological survey at the 18 hectare privately-owned lake. This was followed by a $200,000 wetland restoration project, co-funded by the regional council, Waikato River Authority, the Waikato Catchment Ecological Enhancement Trust and Waipā District Council.
The effort to protect Lake Maratoto reflects the fact that Waikato peat lakes are valued for their unique genetic diversity, scientific interest and recreational opportunities. The lake is considered to have the most intact peat bog vegetation of all of the Waipā peat lakes and supports a number of threatened species.
The most significant ongoing threat to Lake Maratoto and surrounding peat land is that the existing water levels are not high enough to sustain the unique peat bog vegetation around the lake. This has also allowed pest plants, like gorse, Chinese privet and blackberry to establish on the drier soils.
The hydrological survey confirmed that lake water levels frequently dropped below acceptable levels defined in the Waikato Regional Plan. So the council has been looking into solutions to ensure the lake’s outlet weir – a barrier affecting water flows - keeps the water at the right level.
The council’s monitoring manager Dr Ed Brown says getting things right will require a fine balance.
“If we install a weir that lets through too much water, we end up draining the lake and surrounding peat bog too much and we’ll lose valuable flora and fauna. But if we block the outlet completely, we run the risk of flooding the surrounding farm land.”
Over the last three years, landowner Bruce Davies has been working closely with the council to stabilise the water level in the lake.
This work is building on important improvements to the lake already achieved by the installation of an original weir by Bruce that was designed to allow a more even outflow. It minimised erosion, sustained life downstream and provided a solution during heavy rain.
“The farm land and lake are both important to me, as they were to my family before 1969, and we’ve been trying to keep the water in the lake at manageable levels. Summer evaporation is always going to be a concern.
“The farm has provided year-round vehicle access using existing tracks, while we’ve been working to improve accessibility to the lake by creating a walkway. And I have also, along with my neighbour Judith, undertaken extensive planting of native plants.”
Council catchment management officer Jackson Efford says the hydrological survey has also helped make informed decisions about the best plants to use in the multi-agency restoration project for the lake’s wetland.
“We decided to plant things that do well in slightly drier conditions, after the water level trends showed this was the smarter thing to do.”
Bruce and neighbouring landowner Judith Graham have been very supportive of the wetland restoration project and they’re both pleased with the results so far.
“We’re still in early stages but the wetland surrounding the lake looks a lot better,” Judith says.