Lake Waikare

The lake has extremely high levels of sediment and nutrients, and has been devegetated since the late 1970s. An algal bloom, caused by non-toxic microscopic algae Monoraphidium, reached considerable levels in June 2014, turning the water a characteristic shade of orange, and has been a regular occurrence ever since. Cyanobacteria (blue-green algae) blooms have also become abundant in recent years. The lake acts as an important flood storage reservoir for the Lower Waikato Waipā Flood Control Scheme, discharging to the Whangamarino River and, in turn, the Waikato River. Flood protection works have decreased the average lake level by around 1 m, and reduced the extent of lake level fluctuation, which resulted in loss of around 840 ha of wetlands.

Lake Waikare’s condition is a result of modifications associated with the flood scheme, point source discharges, non-point source agricultural discharges, and invasion by plant and animal pests. These issues occur at a large scale and combine to create a difficult restoration scenario. In 2007, the Lake Waikare Steering Group assessed management options to improve the condition of the lake. Since then, a number of agencies and stakeholder have undertaken initiatives to fence and restore the margins of the lake and and improve wetland habitats. Due to high densities of koi carp, rudd and catfish, pest fish removal methods have been the focus of recent research and management initiatives. Together with other agencies and stakeholders, Waikato Regional Council has installed a pest fish trap at the outlet of Lake Waikare. The trap has been very successful, and by 2015 had removed around 35 tonnes of pest fish. Trapped pest fish are turned into fertiliser. Lake Waikare is identified as a priority 1 waterbody for stock exclusion in the Waikato Regional Plan, but is not yet fully fenced. Up to 20 km of fencing may be required to fully protect the lake margins from stock.