MEDIA RELEASE

Tenders called for Lake Rotoiti wall construction

For immediate release: Friday 3 November 2006

Environment Bay of Plenty is calling for tenders for the construction of a multi-million dollar, in-lake wall that should significantly improve Lake Rotoiti’s water quality.

The structure will stop Lake Rotorua’s nutrient-laden water flowing into Lake Rotoiti. Scientists expect this to improve the algae-ridden lake’s water quality in less than five years.

After receiving the go-ahead from the Environment Court, the council is now advertising for tenders for the wall’s construction. Tenders will close around New Year, with construction expected to start in June next year. It will take about nine months to build the kilometre-long structure at a cost of about $15 million. Rotorua District Council will manage the construction project, which is funded jointly by Environment Bay of Plenty and central Government.

“The project is moving into its practical phase now, so it’s an exciting time,” says Environment Bay of Plenty’s operations committee chairman Bill Cleghorn. Mr Cleghorn says the structure is “a critical step” for the lake’s future when taken in conjunction with Rotorua District Council’s reticulation of sewage in lakeside communities.

The diversion structure will be driven into the lake bed and rise to just above lake level. It will start at the entrance to the Ohau Channel, which links Lake Rotorua and Lake Rotoiti, and run about 75 metres offshore parallel to State Highway 33.

The main length of the wall will be solid steel sheetpile.

Nutrients flowing from Lake Rotorua through the Ohau Channel are a major cause of Lake Rotoiti’s water quality problems. Over a year, nearly half the channel’s flow goes directly into the Kaituna River. However, the rest moves around the main body of Lake Rotoiti before exiting and going down the river. This results in the algae blooms that have dogged the lake over the past three or four years. Scientists do not expect the altered flowpath to have any significant effect on Kaituna River water quality. However, the council is working with local communities to develop a strategy for the river and Maketu Estuary.

The wall is one of a number of measures being taken to improve water quality in both lakes, including a massive sewerage reticulation project by Rotorua District Council.

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