Lake Okareka is one of four small lakes lying between Lake Rotorua and Lake Tarawera, in the Bay of Plenty region of New Zealand's North Island. The others are Lake Rotokakahi (Green Lake), Lake Tikitapu (Blue Lake), and Lake Okataina. All lie within the Okataina caldera, along its western edge.
The lake has a circumference of 6 miles (9.7 km) and lies about 60 metres (200 ft) above Lake Tarawera. Its outlet flows underground for half a mile and forms the Waitangi waterfall. In fact, the Okareka lake seems to be connected with the Tarawera by underground channels.
This small and little-visited lake is a place of much charm, surrounded by hills nearly everywhere thickly wooded. It is quite near, but out of sight from the tourist motor route of Rotorua and Tarawera; a side road gives access to it. Anglers find good sport there, but otherwise its solitude is not disturbed yet. Many years ago a settler acquired some of the land around it, and built his house on a low-lying isthmus which connects an island-like hill in the middle of the lake with the mainland. Some of the frontage is still in private hands, but the greater part of the sylvan basin in which the lake lies has now become residential property.
Okareka means "the lake of sweet food". In early times, Māori grew sweet potatoes or kumara around the outside of the lake. It first described in print by Sir George Grey, and poetic mention of it is made by Alfred Domett in his "Ranolf and Amohia." Grey visited it on the course of his travels through the Lakes Country to Taupo in the summer of 1849-50. The journey is described in that rare little book entitled "Journal of an expedition Overland from Auckland to Taranaki", written for the Governor by his secretary G. S. Cooper, with a translation into Maori by his interpreter, Piri-kawau; the book was published in Auckland in 1851. In those days, the route from Ohinemutu to Tarawera was a track which skirted the shore of Okareka and reached the large lake near the mission station called Kariri (Galilee). It was a blistering hot day when Governor Grey and his party took the foot trail from Rotorua to Tarawera, and the narrator says they were "nearly stewed".
"We reached the beautiful lake of Okareka," the journal entry for 27 December 1849, runs, "just at a place where there is a spring of deliciously cool water, wherewith we all refreshed ourselves and then proceeded to cross the lake in canoes. The lake is really an extremely pretty sight, the shores being lofty and wooded, with the exception of a valley at each end, where the roads run. A peninsula, on which stands the pa called Taumaihi, juts out into the centre of the lake. The waters are beautifully clear, and very deep. There is no apparent outlet to this lake. Its vent consists of an underground stream, which is hidden for about half a mile, and then makes its appearance, looking like a fountain, gushing through a heap of rocks and square stones of a basaltic formation, whence it makes its way in a small stream to Tarawera, the level of which is about sixty feet lower than that of Okareka, and into which the water falls down a declivity of twenty feet, forming a beautiful cascade, surrounded and overshadowed by a clump of karaka and other evergreen trees."
In those days the shores of Okareka were a scene of Maori life; there were cultivations on the waterside, and the natives fished the waters for whitebait, the koura crayfish, and the little fish called toitoi, which abounded there before the Pakeha trout was introduced. In the ‘sixties Alfred Domett visited Okareka and Tarawera by the track Grey took.
Some of the most beautiful forest in the Lakes country is in this reserve, extending to the lofty western side of Lake Okataina and the Whakapoungakau Range. But red deer roam the bush, and however desirable they may be from the Rotorua sportsmen’s point of view they are not doing any good to this forest sanctuary.
Renowned for its natural beauty, this lake has an adjacent settlement of approximately 600 people. The lake is easily accessible from the well-known tourist location of Rotorua.
Lake Ōkareka has reasonably clear, clean water and is used extensively for recreation such as boating, swimming and fishing. However, the quality of the water has been declining over recent years due to excess levels of nitrogen and phosphorus. These nutrients come from surrounding farmland, residential septic tanks and from the release of existing and accumulated nutrients from sediments on the lake bed.
The Lake Ōkareka Catchment Management Plan was developed in 2004. This is a long-term plan to improve the water quality of the lake, through changes like sewage reticulation, in-lake chemical treatment and farm nutrient management. It has been calculated that the load nutrients needed to reach the target TLI of 3.0 are 2.5 tonnes per year of nitrogen and 0.08 tonnes per year of phosphorus.
The Trophic Level Index (TLI) is an overall indication of lake health based on a number of different criteria, values represent a three-yearly average. Better quality sites have a lower TLI. The three-yearly average for Ōkareka indicates little change over the last five years.