Weather Events Keep Lake High

27 March 2023

Weather Events Keep Lake High

Persistent weather events throughout January and February have seen 600mm rain recorded at the Okawa Bay monitor during that period. Accordingly, lake levels have remained above or close to the top of the operational range with Rotoiti levels reaching RL279.487 metres on February 6th (almost 90mm above the consented range and the highest recorded since the 1960-70s). Concerns have been expressed over resultant erosion around the lake margins which has occurred in numerous areas.

The uncertainties surrounding ongoing weather patterns have influenced management regimes. BoPRC sought to maintain Rotoiti levels close to the operating median of RL279.15 metres in the early  stages of summer to alleviate any extended dry periods. However, ground water levels in the Rotorua catchment remained abnormally high from the end of November. The frequent disruption of rain events from the beginning of December kept the level closer to the operating maximum of RL279.20 metres. Unfortunately it remained near the top of the range when the two weather bombs at the end of January – early February eventuated.

The Okere gates were held wide open from 28 January to 9 March and continue to be managed in response to forecast weather patterns. Constant high flow rates out of the Ōhau Channel due to enduring ground saturation throughout the Rotorua district have significantly contributed to the ongoing abnormal lake levels. These high outflows have also severely restricted Ōkere/Kaituna river activities with few commercial rafting opportunities over the past 6-8 weeks. It remains to be seen whether the more settled weather conditions predicted for autumn in fact prevail.