Lake Rotokākahi

The lake flows to Lake Tarawera via the Wairoa Stream (also known as Te Wairoa) past the buried Te Wairoa village and its Wairere waterfall.[1]^: 52[3] The Wairoa Stream when it leaves Lake Rotokākahi has a mean flow rate of 310.6 L/s (10.97 cu ft/s) but it picks up subsurface water and tributaries so when it enters Lake Tarawera it has a mean flow rate of 347 L/s (12.3 cu ft/s).[1]^: 25 From the air the lake looks emerald green related to its shallow, sandy bottom. The lake is 394 m (1,293 ft)[2] above sea level and 24 m (79 ft)[2][1]^: 24 below the level of the neighbouring Lake Tikitapu to its north. Its eastern arm is separated from Lake Tikitapu by a lava dam generated during a rhyolitic eruption, at the south-western margins of the Ōkataina Caldera now dated at 15,635 ± 412 cal.yr BP,[4]^: 15. It contains a small island in its western arm, Punaruku Island and its southern arm has a larger island Motutawa Island.[1]^: 52 While the catchment flows into the Tarawera River watershed in due course, the south-western aspect of the lake is only a very short distance from the Waikato River watershed.[1]^: 52

It is named for its abundance of kākahi (freshwater mussels).[5][6]

The lake had Brown trout introduced in the 1870's and later Rainbow trout were introduced.[5]^: 60

The lake is classified as mesotrophic,[5]^: 10 with moderate productivity and water quality, but has not been assessed recently.[7] Its trophic level index was 3.6 in 2014 which was a decline and relatively high for a local lake.[1]^: 5 This may be because 26.3% of its catchment was pasture in 2007.[5]^: 10

The main tribe occupying the Lake Rotokakahi area at the time of European settlement were the Tuhourangi/Ngati Tumatawera, who had migrated from the Rotoiti area following various feuds with neighbouring tribes.[5]^: 59 During early European settlement Kaiteriria on the southern lake shore was a base for armed constabulary.[5]^: 60 The lake has been under the authority of the Te Arawa iwi, Tūhourangi and Ngati Tumatawera since 1948, when there was disturbance of the tapu,[5]^: ii, 61 and remains largely undisturbed[8]

This small island in the lake is notable as the site of the 1822 slaughter of a part of Ngāpuhi, as an act of vengeance for relatives killed by the same Ngapuhi warriors in Te Totara, Thames.[5]^: 59 This led to the revenge raid of Hongi Hika in 1823.[5]^: 59 The island was the main historic stronghold of Tuhourangi/Ngati Wahiao,[5]^: 59 and tradition has it as the resting place of the bones of Hinemoa.[5]^: 62

The New Zealand Ministry for Culture and Heritage gives a translation of "tawa tree island" for Motutawa.[6]