Wiawhakaata (Lake Hayes) is a 280 hectare lake (31 m maximum depth), that has become eutrophic due to elevated nutrient inputs from its catchment. The Lake Hayes catchment has been used for agriculture since late 1800s, but severe degradation was not observed until the late 1960s, when the bottom waters of the lake became anoxic and nutrients previously bound to the lake sediment began to dissolve into the water column (source www.savelakehayes.org.nz/the-lake)
