Ohau Channel Wall Lack of Action

8 June 2025

Bay of Plenty Regional Council Slow to Act on Ohau Diversion Wall

Here is an update from John Gifford, Chair of the LWQS.

The Ohau Channel Diversion Wall is a critical component of the overall Rotorua Lakes Restoration Programme and in particular the restoration of Lake Rotoiti from its poor condition in the early 2000s when this Lake was affected by regular algae blooms and relatively high TLI values up to 4.5 and above (the TLI target for Lake Rotoiti now is 3.5).

Corrosion of the wall was first reported in 2014, but by 2019 there was early evidence that the main barrier component of wall (the sheet piles) had developed perforations. By 2023, these small perforations had evolved into substantial holes and work completed in 2023 indicated that the level of leakage was appreciable with estimates ranging from 3 - 10%. In 2025 we have no new information on the state of the holes and the level of leakage.

The Lake Rotoiti Community and LWQS are working with the BOP Regional Council to get a commitment to repair the wall so that it will remain fit-for purpose for the duration of the consent - to 2052. This timeframe aligned with the period that it was expected for significant improvements in the water quality of Lake Rotorua to occur and then to allow for the ongoing benefits of the diversion wall to be re-evaluated and its future determined.

Progress in developing a schedule for the repairs is still work in progress. Reports on the options along with indicative costs have been prepared by the Regional Council and further consideration of the repair options is scheduled for consideration by the Council in August.

At this stage the Regional Council does not see the repairs as being urgent (contrary to many other Lake stakeholders). Further support from the community is needed- through the LWQS and LRCA to assist with pressing for a more timely commencement of repairs to the Diversion Wall.

We are determined to have the wall repaired in a timely manner and will take whatever action necessary.