Quarterly Water Quality Report – February 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.
The most recent Quarterly Water Quality Report to February 2024 is slightly different to previous reports in that it focusses on the eDNA monitoring that has been undertaken in the catchment/scheme area in December 2023 and January 2024.
eDNA is material left behind by organisms (e.g. fish, insects, birds etc.) as they move through their environment. This material might be skin, hair, scales, mucus, faeces and other cells or tissue. Monitoring eDNA can identify thousands of species of fish, insects, crustaceans, birds, mammals, amphibians, plants, fungi, bacteria and other organisms.
The types of species identified allows OWL to attribute a score and describe the broad ecological health of a waterway. Depending on the eDNA score achieved, the ecological health of a waterway can be rated from Pristine to Very Poor, with higher scores indicating better ecological health.
eDNA sampling in the North Opuha, South Opuha and Opuha rivers was carried out by OWL, with all other sampling undertaken and funded by Living Landscapes South Canterbury.
Key Findings
- eDNA sampling was undertaken in the Opuha Scheme and wider catchment in December 2023 and January 2024, with ecological health ratings achieved from Average to Pristine.
- Upstream locations or locations higher in the catchment generally recorded better eDNA scores and higher ecological health ratings than locations downstream in the catchment.
- The Lake Opuha tributaries were rated from Good to Pristine with the South Opuha River achieving the highest rating of Pristine.
- The Opuha River was rated Good, and the Te Ana Wai River recorded ratings of Excellent and Good.
- The Upper Opihi tributaries were rated from Average to Pristine, with upstream locations scoring better than downstream locations.
- The ecological health ratings for the Opihi River ranged from Average (Burke’s Pass) to Excellent (Fairlie). A decrease in the ecological health rating was observed between Fairlie (Excellent) and Raincliff (Good) – Raincliff is downstream of where the high nitrate tributaries of the Upper Opihi enter the Opihi River.
Download the full report here.
