They are close to a contact between outcropping Early Jurassic “greywacke basement” and the overlying Tertiary rocks consisting of claystones, limestones and sandstones.

[24] In the confiscated area, which included the lake,[7] as part of a policy of opening up land for settlement under the deferred payment scheme, the Government built bridleways from the river, to give access to two 20,000 acres (8,100 ha) blocks.

[28] However, the surrounding roads remained poor, so the lake and its neighbouring streams were used for transport, a Whangape Launch Company being set up in 1906 to convey goods from Rangiriri.

[32] Until at least 1869 the lake was clear enough to see plants growing in the deepest parts and it supported a diverse community of native submerged vegetation.

[35] Frequent monitoring by Waikato Regional Council from 2008 to 2013 showed a Secchi depth of 0.04 m to 0.69 m (average 0.24 m) and chlorophyll concentrations exceeding 100 mg m-3.

In 1977–1979, the Wildlife Service found the same plants, but also the introduced Potamogeton crispus, the native Myriophyllum propinquum and rediscovered blunt pondweed.

[33] In 1987 the macrophyte beds declined to about 10% of the lake area,[42] turbidity increased (possibly due to coal mine waste)[43] and they were dominated by hornwort, another invasive exotic.

High levels of suspended sediment and phytoplankton biomass, largely shade out re-establishment of submerged macrophytes.

[38] 48% of it consists of turf communities, categorised into 21 types, the longest being some 3.5 km (2.2 mi) of 'Indian doab–water purslane (Hydrocotyle hydrophila) herbfield'.

Dominant species were usually perennials, with the alien Mercer grass and the indigenous emergent spike sedge most common.

[45] In 1871 vegetation was dominated by raupō, flax, sedge, kahikatea, lancewood and shrubs such as Raukaua anomalus and swamp māhoe (Melicytus micranthus), which remain west of the lake.

Endangered or uncommon turf plants include Amphibromus fluitans, Fimbristylis velata, Carex cirrhosa, C. gaudichaudiana, Lachnagrostis striata, Pratia perpusilla, pillwort and mud buttercup (Ranunculus limosella).

Threats perceived by DOC were encroachment of the weeds Paspalum distichum, Centipeda cunninghamii, Myriophyllum aquaticum, and Ludwigia palustris, and the effects of cattle grazing.

[42] The Awaroa Reserve is mainly formed of crack willow forest, with some open swamp of flax, cabbage tree, mānuka, and mingimingi.

A pair of mute swans, presented by Sir George Grey to Captain Hutton, hatched their second brood in 1870,[49] were donated to the Auckland Acclimatisation Society in 1871,[50] by 1873 were a larger flock[51] and, by 1878, there were enough to send some elsewhere.

[6] Although the lake is identified as a priority 1 waterbody for stock exclusion[55] in the Waikato Regional Plan,[36] only about a third has been fenced to exclude cattle.

[46] In 1956 the local MP, Hallyburton Johnstone, suggested the lake could be turned into farmland "at no great cost",[63] a claim probably based on a 1933 estimate[64] and a 1911 engineers' survey.