As of Tuesday this week, water levels were sitting at 370.9m, just 1.3% of the lake’s total capacity, slightly above the lake’s lowest reading of 370.1m in March 2015.
The 2023/24 irrigation season ended two months early for Opuha Water Ltd shareholders and water users when the lake dropped below 5% (373m).
Without rain, it is expected the Opihi River above the junction with Temuka River may begin drying up in some places.
The remaining 3m in the lake have been retained for environmental flows in an effort to increase the likelihood that the Opuha/Opihi flows will stay connected, which is critical for the health of the river ecosystem.
Minimum flow requirements have also been reduced.
Opuha Water Ltd is transitioning to "natural flows" where inflows into the lake equal outflows from the dam.
Opuha Water Ltd will continue to collaborate with stakeholders to monitor the health of the downstream river and check if fish salvages are necessary.
An Opuha Water Ltd spokesperson said that while it was a situation no-one in the community wanted to see eventuate, it was important to acknowledge that the Opuha Dam had done exactly what it was designed to do — provide environmental flows, community supply and reliable irrigation to the South Canterbury community.
"Unfortunately, the persistent El Nino weather pattern we are experiencing along the east coast has pushed the dam to the limits of what it can provide.
"Importantly, if the dam was not there, it is estimated by ECan that the ‘natural’ flows in the Lower Opihi River at State Highway 1 would currently be well under 1 cumec, a flow which would likely disconnect the river."
