Lake Whangape
Lake Whangape is shallow, supertrophic, lateral and the second largest lake in the lower Waikato River basin. One source said the name translated to 'a large sheet of water', another that it was a chief's name.
From the 1860s the catchment has lost most of its forest cover and the lake has changed from clear and rich in aquatic vegetation to a murky, algal lake.
Geology
The lake is a lateral lake, dammed by a levee of the Waikato, probably built up as a result of sea-level rise and sediment from the Taupo Volcanic Zone about 2,000 years ago.To the west of the lake the rocks are made up of the 30m year old Whaingaroa and Glen Massey Formations, the Whaingaroan rocks of the Te Kuiti Group. The Karapiro Formation outcrops towards the east of the lake.
Hot springs
Two springs (ranging from to and many seepages occur along Te Maire Stream, a tributary of the main lake feeder, Awaroa Stream, about west of the lake. They are close to a contact between outcropping Early Jurassic “greywacke basement” and the overlying Tertiary rocks consisting of claystones, limestones and sandstones. It has been suggested that Waikorea, Naike and Waingaro may all source their water from depths of more than, as they all have similar chemical composition.The springs have been named as Whangape, Awaroa, Naike, Waiora, Te Maire, or Te Puia. In the 1890s boat trips were made to the springs from Rangiriri. In 1868 the temperature was measured at. A 1905 earthquake enlarged the main spring. The springs are on private land and not now open to the public.
History
The lake was on the edge of the area which Ngāti Tipa had settled. At the entrance to the lake, Ngapuhi killed 40 or 50, during the Musket Wars in 1832. In 1843, Rev Benjamin Ashwell intervened in a dispute between Ngāti Pou and Ngāti Mahuta over an eel weir at the lake outlet. It seems it wasn't fully resolved, for, in 1866, a similar dispute was settled by giving the Ngāti Mahuta hapus, :mi:Ngāti Naho|Ngāti Naho and Ngāti Tipa, equal rights over tuna at the lake.In 1864 the Whangape area was described as inaccessible to the British troops in the Invasion of the Waikato, due to the swamps and bush.
Whangape was one of 5 ridings making up Raglan County Council when it was formed in 1876.
In the confiscated area, which included the lake, 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 blocks. A road to Awaroa was approved in 1878. The northernmost of the 2 routes began at Churchill, a settlement which then stood on the west bank of the river about west of Rangiriri. By 1881, had been opened as far as Glen Murray, through heavy swamp at the Churchill end. By 1883 a through track from the Waikato River to the West Coast was in existence. At the same time another was built from south of the lake, towards the Awaroa. By the middle of 1883, nearly had been opened Work began on roads at Rangiriri in 1889, the first section being to the lake.
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. Earlier, in 1894, Parliament had been asked to "have obstructions in the shape of eel weirs removed from the navigable creeks flowing from Whangape Lake into the Waikato River, so as to enable steamers now running on the Waikato River to carry goods for settlers in that district." In 1889 the weir had been partly removed to allow a boat to get through.
Water levels
Between 1968 and 2000 the water level in Lake Whangape fluctuated between and above sea level. Water flows into the lake from the Waikato River, when it is high. Since 1999 a weir at the outlet has maintained the minimum water level at.Pollution
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. In the 1890s the native forest catchment was cleared for pasture.A 2006 Ministry for the Environment report said water quality was declining. Frequent monitoring by Waikato Regional Council from 2008 to 2013 showed a Secchi depth of 0.04 m to 0.69 m and chlorophyll concentrations exceeding 100 mg m-3. Between 2010 and 2014, 62% of samples exceeded recreational guideline levels for blue-green algae.
Wildlife
Parts of the lake and wetlands around it were gazetted as a Wildlife Management Reserve of in 1986. To the west, Awaroa Wildlife Management Reserve extends up the Awaroa Stream, on of the floodplain.Aquatic vegetation
's 1869 survey found a diverse, low growing mixed plant association. Quillwort, fennel pondweed, blunt pondweed and red pondweed were abundant, waterwort, horses mane weed and horned pondweed were common and Lepilaena bilocularis and green algae were also present. The only charophytes remaining by 1993 were Nitella and P. cheesemanii. It was claimed in 1889 that growth was too lush to allow a canoe to be paddled through parts of the lake.By 1921 the lake was said to be infested with weeds and by 1958 the original vegetation was almost completely replaced by Egeria densa, first seen in the Waikato in 1946. Elodea Canadensis and Indian doab were also identified. In 1977-1979 the Wildlife Service found the same plants, but also the introduced Potamogeton crispus, the native Myriophyllum propinquum and rediscovered blunt pondweed.
Fish and other water life
Despite the pollution, 14 fish species live in the lake, with large populations of native fish, including short-finned eel, Galaxias maculatus, longfin eel, common bully and grey mullet, as well as pest fish - koi carp, mosquito fish, catfish and goldfish. Perhaps due to turbidity created by mining waste, or by koi carp, the native mysid shrimp is the common food of eels, smelt and common bully.Riparian vegetation
Much of the lakeside vegetation grows in mineralised swamps. 48% of it consists of turf communities, categorised into 21 types, the longest being some of 'Indian doab–water purslane herbfieldIn 1871 vegetation was dominated by raupo, flax, sedge, kahikatea, lancewood and shrubs such as Raukaua anomalus and swamp māhoe, which remain west of the lake.
Raupo remained on much of the lake’s margin until the 1950s, but by 1991 only 9% remained in a narrow fringe. As early as the 1890s willows were mentioned as a problem and in 1917 the river board was clearing the stream of willow. Now the shores have been colonised by crack and grey willow and floating sudds of American primrose willow and Amazonian parrots feather are now along most of the lake shore. However, a 1991 survey found 541 vascular species of which 300 were indigenous. Endangered or uncommon turf plants include Amphibromus fluitans, Fimbristylis velata, Carex cirrhosa, C. gaudichaudiana, Lachnagrostis striata, Pratia perpusilla, pillwort and mud buttercup. Threats perceived by DOC were encroachment of the weeds Paspalum distichum, Centipeda cunninghamii, Myriophyllum aquaticum, and Ludwigia palustris, and the effects of cattle grazing.
The Awaroa Reserve is mainly formed of crack willow forest, with some open swamp of flax, cabbage tree, manuka, and mingimingi. It also has of regularly flooded kahikatea forest, with kowhai, totara, matai, pukatea and climbers, including Supplejack, swamp lawyer, bush lawyer, jasmine and pōuwhiwhi and haaka ground cover.
Birds
56 species have been recorded on and around the lake, the commonest being black swan, Canada goose, paradise duck, grey duck, mallard, shoveler and pukeko. Other birds include shag, bittern, heron, crake, pied stilt, gulls, fernbird and grebe.Since colonisation some birds have been introduced and others have become locally extinct. A pair of mute swans, presented by Sir George Grey to Captain Hutton, hatched their second brood in 1870, were donated to the Auckland Acclimatisation Society in 1871, by 1873 were a larger flock and, by 1878, there were enough to send some elsewhere. The Society added geese to the lake in 1905. Karakahia, or Australian white-eyed duck once bred on the lake and were reported in 1868.