Aparima River

The rolling hill country in its middle reaches is more agriculturally developed, and much of the lower catchment has been extensively modified over the last century, with the drainage of wetlands and the straightening and shortening of streams to assist in flood management activities.

Major tributaries of the Aparima River include the Hamilton Burn in the upper reaches and the Otautau Stream in the lower reaches. The Otautau Stream has very poor water quality. The main pressures on water quality in the Aparima catchment are due to dairy farm intensification as drain networks in the lower catchment can discharge degraded water to receiving streams. Overland flow and nutrient loss from wintering practices contribute significantly, particularly when soils are saturated. Flood and drainage works also potentially impact water quality in the Aparima catchment.

Environment Southland collects water quality information from five sites in the Aparima catchment. Nuisance algal growths, driven by low flows and high nutrient levels and temperatures, increase further down the catchment. Macroinvertebrate health indices progressively decline at sites down the catchment.

During the summer there is weekly bathing monitoring at some sites. See the Environment Southland website for details.