Lake information

Rotorua’s lakes are stunningly beautiful. But for many decades they have been under increasing pressure from human activities like residential settlement and farming. And that pressure has taken its toll.

Human activities such as residential settlement, farming, forestry and recreation all affect nutrient levels in lakes.

The major pressure on the lakes is the intensification of farming. Wastewater from lakeside communities is also a contributing factor. In the past, these communities have disposed their wastewater to septic tanks, contaminating the lakes with nutrients and bacteria. However over the next seven years, wastewater from these lakeside communities will have most of its nutrients removed – either through reticulation and treatment, or through advanced on-site effluent treatment systems.

The greatest contribution of nutrients to the lakes (with a few exceptions) now comes from rural land use in the catchment. Land use intensification into sheep, beef, dairy, deer, cropping and lifestyle properties has increased nutrient runoff to the lake over time. Fencing off streams and lake edges from livestock and planting gullies and riparian margins has tended to offset the increase in phosphorus loss to the lakes so far. However, nitrogen inputs from rural land use have continued to increase around the more degraded lakes.

The nutrient pressures show up as a deterioration in lake quality over time. Short-term ‘events’ like algal blooms occur where the water quality becomes noticeably affected. In the worst cases, like Lake Rotorua, the lake condition is seriously affected for much of the year.

The lakes

The following pages have information on specific lakes

• Lake Okareka
• Lake Okataina
• Lake Okaro
• Lake Rotoehu
• Lake Rotoma
• Lake Rotorua/Rotoiti
• Lake Tarawera
• Lake Tikitapu

You can also find more information on the Rotorua Lakes Report Cards page.

The Goal

Environment Bay of Plenty, Rotorua District Council and Te Arawa Lakes Trust are working intensively with the community to protect, and in some cases improve the water quality of the Rotorua Lakes. This joint project is called the Rotorua Lakes Protection and Restoration Action Programme.

Action Plans and Working Parties

A major focus of the Rotorua Lakes Protection and Restoration Action Programme is the development of Action Plans for nine lakes: Rotorua, Rotoiti, Okareka, Okaro, Rotoehu, Tarawera, Rotoma, Tikitapu and Okataina. These lakes have water quality that is worse than their target water quality. Action Plans focus on ways to reduce nutrients in the lakes. Some actions tackle nutrients already in the water while others focus on cutting back the amount of nitrogen and phosphorus washed overland or leaching through groundwater systems.

Eventually all the Rotorua lakes will have an Action Plan. Lakes Okareka and Okaro already have an operative Action Plan. Lakes Rotorua, Rotoiti and Rotoehu have proposed Action Plans that are going through a public consultation process. Action Plans for Lakes Tarawera and Rotoma are being drafted. Background work for Lakes Tikitapu, Okataina and Rotokakahi's Action Plans are underway. An Action Plan process for Lakes Rotomahana and Rerewhakaaitu will start in July 2008, unless their water quality declines before then. Lake Rotokakahi's Action Plan process is dependent on discussions with the lake owners.

Electronic versions of each lake’s Action Plan, or progress towards the Action Plan, can be found on each lake’s specific webpage.

A working party is central to the development of each Action Plan. A working party has political representatives from regional and district councils, landowners, iwi, and community and interest groups. The working parties discuss and evaluate options and solutions to improve lake water quality, identify knowledge gaps and give recommendations for action. Two independent Technical Advisory Groups (for land use and water quality) help evaluate the options from a scientific perspective.

Regulation is also being used as a tool to improve water quality. Rules in Environment Bay of Plenty's Proposed Regional Water and Land Plan, particularly 'Rule 11', set environmental standards to limit nutrient loss to the lakes.

Ohau Channel Diversion

The Ohau Channel Diversion Wall along the western edge of Lake Rotoiti diverts water from Lake Rotorua (via the Ohau Channel) away from the main body of Lake Rotoiti, and down the Kaituna River instead. This action is expected to improve Lake Rotoiti's water quality within five years, with no noticeable impact on the Kaituna River.

Clean Your Boat

All of Rotorua’s lakes are currently free of pest fish, like koi carp and catfish. Some lakes are free of all or several species of aquatic weeds. If pest fish or new weeds establish in the Rotorua lakes, they are likely to degrade water quality, become a nuisance to lake users, and escalate the decline in native aquatic plant communities.

Your boat can bring new aquatic pests into a lake. A single fragment of weed can transfer the eggs of pest fish or cause a new infestation of aquatic weeds.

Skippers must inspect their boats, including propellers anchor chains and trailers, when leaving a lake and before entering a new lake. Please remove all weeds, flush out jet units, and wash your boat down if necessary.

You have an important role to play in protecting the Rotorua lakes.