The lakes of Chatham Island are diverse in character and water quality, shaped by the island’s unique peat-based geology, low-lying topography, and limited development.
Broadly, they can be grouped into two types:
• Peat-stained inland lakes – nutrient-rich, dark-coloured waterbodies draining from peatlands.
• Clear coastal dune lakes – smaller, sand-based lakes with limited catchment disturbance and clearer water.
Water quality monitoring is operated by Environment Canterbury in partnership with the Chatham Islands Council. Routine monitoring began in 2005 and includes sampling at a selected range of lakes across Chatham Island. These sites are sampled quarterly, providing a consistent long-term dataset for assessing the state and trends of freshwater quality across the island.
Key indicators such as nutrients (nitrogen and phosphorus), algae (chlorophyll a) and bacterial levels are monitored to understand how water quality changes in response to land use, geology, and climate.
E.coli, cyanobacteria and secchi disc depth data may be missing from some sites as these indicators are not routinely sampled.
