MEDIA RELEASE
First official step taken to save Lake Rotoiti
For immediate release: Monday 4 July 2005
Environment Bay of Plenty has taken its first official steps in seeking permission to build a $12 million structure in
Lake Rotoiti that should quickly improve water quality.
The regional council has lodged resource consents for the major engineering work, described by project coordinator Paul
Dell as a “one of the most significant single environmental remediations ever undertaken in New Zealand”.
The kilometre-long structure’s purpose is to divert water flowing into Lake Rotoiti from Lake Rotorua, sending it
directly down the Kaituna River and out to sea. It is one of a number of actions being taken to improve water quality in
both lakes under the wide-ranging Rotorua Lakes Protection and Restoration Action Programme.
Environment Bay of Plenty’s manager environmental investigations John McIntosh says the structure will stand on the lake
floor and rise to just above water level. It will be 1250m long, starting below the Ohau Channel outlet, which links the
two lakes, and extending to Te Akau Point. It will be about 75m offshore, running parallel to State Highway 33
The main length of wall will be of solid sheet-pile material that should last for at least 50 years. However, a lighter
style of construction may be needed around the Ohau Channel if there is a lack of a firm foundation for piles.
Mr McIntosh says that nutrients flowing from Lake Rotorua through the Ohau Channel are a major cause of Lake Rotoiti’s
water quality problems. “Over a year, about 40% of the channel flow goes directly down the Okere Arm and into the
Kaituna River,” he explains. “The rest moves around the main body of Lake Rotoiti before exiting and doing down the
river. The wall is designed to block this flow path, so all of the water goes directly to the ocean.” Scientists say the
change will have very little impact on Kaituna River quality. However, to make sure the river stays protected,
Environment Bay of Plenty is funding the development of a Kaituna River Management Strategy this year.
Without Lake Rotorua’s nutrients, Lake Rotoiti’s water quality should improve within three to five years. The diversion
is enough on its own for long term improvement, Mr McIntosh points out. But it will be supported by sewerage
reticulation in some lakeside communities, upgrades to septic tank systems, and restoration work around lake and stream
margins. “It is also extremely important that we improve Lake Rotorua’s water and a lot of work is being done with that,
including a multi-million dollar sewerage reticulation programme and sewage treatment upgrade. However, Lake Rotorua’s
problems are more complex and it will be many years before we see any improvement if urgent options cannot be
implemented.” This is because the catchment’s groundwater is already laden with nutrients that will seep into the lake
for decades to come, he explains.
Last year, the Government offered to contribute up to $4 million towards the cost of urgent remediation work for Lake
Rotoiti.
Submissions on the proposal are expected to open in early July. Environment Bay of Plenty and Rotorua District Council
will appoint independent commissioners to hear submissions to the consent application. For more information on the
project, please contact 0800 ENV BOP (368 267) or go to www.envbop.govt.nz.
Environment Bay of Plenty has already held a number of meetings to discuss the project with the community. It is also
setting up a display at Maketu and under the sail in Rotorua’s city centre in early July. The display trailer will be
staffed from 10am to 2pm in Maketu on Sunday 10 July and in Rotorua on Monday 11 July, Tuesday 12 July and Wednesday 13
July.
ENDS