Lake Waahi

Lake Waahi has been considerably affected by nutrients and sediment, ongoing issues related to its modification, riparian management, and exotic and invasive fish and plant species. Its level has been substantially reduced, and many of the surrounding wetlands converted to pasture for farming.

The lake has played a significant role in commercial coal mining operations since 1876, both as a water source, and a receiving environment for discharges. Coal mining has contributed large quantities of sediment to the lake, altering the lake’s colour, clarity and chemistry. Coal mining was reportedly responsible for up to 90 per cent of the sediment entering the lake at times.

Waikato Regional Council has monitored the water quality of Lake Waahi since 1995, and installed a monitoring buoy in 2014 to collect real-time information. Recent monitoring results indicate the lake has low water clarity, high nutrient levels, and high phytoplankton density. Blue-green algae have been abundant in recent years.

Lake Waahi is identified as a priority 1 waterbody for stock exclusion in the Waikato Regional Plan. Planting and fencing have been undertaken as part of a collaborative project between Solid Energy, Waikato Regional Council, and private landowners. Lake Waahi has been partillay fenced and in 2011, a holistic restoration programme was established, including riparian management, wetland enhancement, establishment of a community nursery, and control and management of koi carp, in a collboartive effeort involving Waikato-Tainui, Waahi Whaanui Trust, Waikato Regional Council and Genesis Energy.