Lake Tomarata Project

Lake Tomarata is a high value recreationally used lake surrounded by an extensive wetland and is the only one of its kind in the Auckland region. It is pivotal that we protect this lake and wetland complex as only 10% of the New Zealand’s wetlands still exist. A very small subset of these wetlands are considered as lacustrine wetlands. The lake itself is equally unique and is the only example of a peat lake system in the Auckland region. The fact that these two very rare ecosystems exist together in one place makes this site extremely special. 

This lake is ecologically significant and has a rich biodiversity of at-risk native fauna and flora. This site is home to populations of black mudfish, bittern and fairy tern, all of which are threatened/endangered species in New Zealand.

This lake has suffered as a result of on-going agriculture and production forestry in the catchment. Recent increases in recreational use, particularly motorised crafts, as well as invasive pest fish species have also caused significant impacts. The lake water quality has declined over the past two decades and in 2012 the lake was classified as completely non-vegetated in 2012.

We aimed to undertake the first lake wide ecological baseline assessment and identify the key drivers of environmental decline. We want to use this information to inform restoration and management plans and ensure a healthy future for this unique ecosystem.

We started with installing continuous water quality sensors (temperature, pH, dissolved oxygen & light) throughout the water column. These sensors will log measurements every 15 minutes for a year. This will give us an understanding of in-lake dynamics. We also carried out a full ecological assessment across the entire lake where we mapped the location and quantity of fauna and flora.

So far, we have made some amazing discoveries. Despite the lake being classified as non-vegetated we have mapped nearly 2km of native plant beds and have found healthy dens charophyte meadows along the southern end of the lake. We have found freshwater mussel beds on the eastern side of the lake which was a huge finding as no one knew these critically endangered species existed here. We also recently found the first juvenile freshwater mussels ever recorded in an Auckland lake.

The combination of our findings so far indicate that all hope is not lost for this lake. There are signs of natural regeneration and with right interventions we can help restore and protect this ecosystem. We are currently compiling or ecological survey data and will be doing a suite of water quality analysis at the end of the year. We are also using drones and satellite imagery to map the surrounding wetland and establish a baseline vegetation extent.

We have partnered with the regional council and local communities to draft restoration/management plans and we hope to trail in-lake restoration measures next year. If anyone would like to know more please visit our website (https://nzlakes.org) and Facebook (https://www.facebook.com/AotearoaLakes) and contact us if you want to get involved.