The Mamaku Ranges are a range of rugged hills in the North Island, New Zealand. Located to the west of Lake Rotorua and north of Lake Taupo, they lie to the immediate south of the Kaimai Ranges , Coromandel Peninsula. The hills terminate in the south with the valley of the Waikato River. Extending from Karangahake Gorge near Paeroa, southward to the Mamaku Plateau, the Kaimai-Mamaku Forest Park gives protection to the rugged bush covered ranges for soil, water, ecological, scenic and recreational values. The range is extensively forested, with the Kaimai-Mamaku State Forest and Kinleith Forest both covering a considerable part of them. The forest includes Kauri trees growing at the far southern limit of their natural range.
Human activity throughout the ranges from early Maori to the present has left a vast historical legacy including old Maori trails and sites, early coach routes, gold mining relics and logging remains, amongst others.
From the eruptions that created Lake Rotorua, they provide layered aquifers within fractured rock and volcanic sand aquifers.
Rainfall recharge moves rapidly through the surface sandy soils, and into the aquifers that discharges as springs to rivers at the edges of the plateau, such as the famous Blue Spring SOME 80 - 100 years later.
Te Waihou "The New Water" - The history of the Waihou River, as a multi purpose focus for the people of the region, dates back to the time of the first human visitors. The river comes from as far up as the Ngatira Marae, which significantly marks the Eastern boundary of "Raukawa Ki Te Kaokaoroa o Patetere" and therefore the Northern boundary of the Ngati Raukawa.
It was a journeying place of King Te Wherowhero Tawhiao, the second Maori King of New Zealand, as it provided him with his main travelling route. The river gave him food and the flax was used for many purposes. Also, Kahupeka, a Tainui tupuna, set off with her son shortly after her husband's death to wander around the Central North Island. On her travels, the Upper Waihou River was one of the main rivers that her and her son crossed while travelling from Pirongia to Te Aroha, and again from Te Aroha to Whakamaru. The river was an important thoroughfare and provided food and flax for local people and visitors alike. The upper Waihou River was one of the main rivers crossed during her travels through the Waikato.
In 1938 the Edmeades family settled and farmed the land alongside the Upper Waihou. They cleared much of the fern and manuka that previously clothed the riverbanks.
During WWII trenches were dug along the upper river due to fears of foreign invasion. They were never used and eventually were filled.
The Waihou Stream is totally spring fed. Water from the Mamaku Plateau takes anywhere between 50-100 years to reach the Blue Spring Water flows from the Blue Spring at a rate of 42 cubic metres per minute (9240 gallons per minute). The water temperature of the Blue Spring is a constant 11 degrees celsius, come winter or summer.
The reason for the blue colour (and high visual clarity) of the Waihou River and its spring source is the high optical purity of the water. Pure water is intrinsically blue in hue because it absorbs red light leaving only blue and (some) green light to be transmitted to the observer's eye. Pure natural waters are blue to blue-green in colour because they lack light absorbing constituents. They also tend to be very clear because they lack light absorbing particles. Both particles and light-absorbing matter are efficiently removed during the long residence time of spring water while in aquifers.