Water Quality Challenges in the Waiwera River Catchment
7 November 2018
Every year the Otago Regional Council (ORC) takes to the sky for a birds-eye view of land-use practices during winter. This gives a grand overview of areas that can’t be seen from the ground, and identifies spots that need to be followed up with an on-the-ground visit.
ORC Manager of Environmental Services Martin King said, “The Waiwera River was one of the areas we covered. During the flyover the river was running clear, however we have previously received complaints through our pollution hotline about sediment discharges into the Waiwera. This can affect the health of macroinvertebrates and fish communities,” he said.
Elevated nitrogen levels are another concern for the Waiwera, as this can encourage algae to grow.
“ORC did a science study in the Waiwera last year and found that the nitrogen levels exceeded targets in the Water Plan, as did levels for phosphorus and bacteria,” Mr King said.
“We encourage farmers, particularly in the hill country, to use buffers of rank grass along their waterways. This protects them where there is a risk of sediment getting into them.
“We also recommend keeping stock away from waterways, getting an overseer nutrient budget to understand fertiliser requirements, and good management of effluent and winter crops,” he said.
Regionally significant wetlands were also viewed during the flyover. Wetlands act as good filters for sediment runoff and other discharges, and are often home to flora and fauna that aren’t found anywhere else except a wetland.
Issues identified during the flyover were poor winter cropping practices, lack of riparian margins, and contaminants in swales. Follow-up visits have been carried out to ensure these problems are properly managed and that there is no risk of sediment and contaminants getting into Otago’s waterways.