Quarterly Water Quality Report – August 2024
Opuha Water Ltd publishes its quarterly water quality reports for Lake Opuha and the wider scheme catchment to share with the community the results of our extensive water quality monitoring program. This report focusses on how the low flow conditions during the last several months have affected water quality in Lake Opuha and the North Opuha, South Opuha, Opuha, Opihi and Te Ana rivers.
Key Findings
- The effects of low-flow conditions on water quality in Lake Opuha and the rivers in the Opuha scheme have been assessed by comparing data between 2023 (normal flow conditions) and 2024 (low-flow conditions).
- The number of high turbidity events in Lake Opuha has decreased due to a reduction in rainfall and lower flows from the lake tributaries.
- As lake level decreased from 69% to 1 % there was an increase in lake turbidity from 2.5 NTU to 8-10 NTU.
- Total nitrogen, total phosphorus and chlorophyll-a levels in Lake Opuha are similar between 2023 and 2024.
- Generally, nitrate-N and dissolved reactive phosphorus levels decreased in the Opuha scheme rivers and water clarity increased (i.e. an improvement in water clarity).
- Reduction in rainfall, lower surface runoff, lower flows and interaction with groundwater are all likely to have contributed to the changes in water quality observed between 2023 and 2024.
Download the full report here
