Lake Tarawera is located on Tarawera Rd east of Rotorua city. Lake Tarawera is a picturesque lake and is well known for its rainbow trout fishery. Several lakes in the area drain into it directly or via groundwater, along with geothermal springs on the southern and northern shores. Lake Tarawera is a deep lake; any water flowing into it stays there for around 10 years. The lake has a total area of 4130 Ha and a catchment area of 14520 Ha. The average depth of the Lake is 50 m and at its deepest point it is 87.5 m.
Lake Tarawera, meaning 'Burnt Spear' is one of the largest lakes in New Zealand. The lake was home to many small Maori villages and mission settlements,until the Tarawera eruption in 1886. Legend has it that a "waka wairua" (phantom canoe) appeared on the lake as a portent of death a few days prior to the eruption. Lake Tarawera receives the water from all the lakes in the Ōkataina Caldera. Lakes Ōkāreka, Ōkataina, Rotokakahi, Rotomahana and Tikitapu all drain into Lake Tarawera either via surface water or groundwater flows. Lake Ōkaro and Lake Rerewhakaaitu drain first to Lake Rotomahana, then to Lake Tarawera. Because of this interaction between lakes the catchment of Lake Tarawera (the Tarawera System) is made up of an inner catchment and an outer catchment: Inner catchment – includes the land, surface water and groundwater that drain directly to Lake Tarawera. Outer catchment – includes the land, surface water and groundwater that drain to the seven other lakes in the Tarawera System before draining to Lake Tarawera.
Lake Tarawera’s TLI is currently 3.1 and does not meet its target of 2.6. The target TLI was established through a public process and confirmed within the Regional Water and Land Plan. The main cause of the declining water quality (indicated by a high TLI) is an increase in nitrogen and phosphorus flowing from the catchment. To solve the problem, the level of nutrients entering the lake needs to be reduced to a sustainable load. This involves calculating how many nutrients are flowing to the lake from each source, and estimating the reduction to achieve the target.
A range of actions are currently being undertaken to reduce the nutrient load into the Lake. These include reduce runoff from pastoral farming activities and the development of a sewerage scheme to recover waste water from urban areas around the western shoreline.