Kaipara Harbour is a large enclosed harbour estuary complex on the north-western side of the North Island of New Zealand. The northern part of the harbour is administered by Kaipara District Council and the southern part by Auckland Council. The local Māori iwi is Ngāti Whātua.
By area, the Kaipara Harbour is one of the largest harbours in the world. It covers at high tide, with exposed as mudflats and sandflats at low tide.
According to Māori tradition, the name Kaipara had its origins in the 15th century when the Arawa chief Kahumatamomoe travelled to the Kaipara to visit his nephew at Pouto. At a feast, he was so impressed with the cooked root of the para fern, that he gave the name Kai-para to the district. Kaipara comes from the Māori meaning "food", and meaning "king fern".
Geography
The harbour extends for some from north to south. Several large arms extend into the interior of the Northland Peninsula in the north-east of the harbour, one of them ending near the town of Maungaturoto, only from the east coast. The harbour has extensive catchments feeding five rivers and over a hundred streams, and includes large estuaries formed by the Wairoa, Otamatea, Oruawharo, Tauhoa (Channel) and Kaipara. A number of small islands off the shoreline are connected to the mainland by mudflats at low tide.
The Kaipara Harbour is broad and mostly shallow, as it is formed from a system of drowned river valleys. The harbour shoreline is convoluted by the entry of many rivers and streams, and is about long, being the drainage catchment for about of land. and is over deep in parts. On average, Kaipara tides rise and fall . Spring tidal flows reach 9 km/h (5 knots) in the entrance channel and move 1,990 million cubic metres per tidal movement or 7,960 million cubic metres daily.
The harbour entrance is hazardous for watercraft. Big waves from the Tasman Sea break over large sandbanks about five metres below the surface, two to five kilometres from the shore. The sand in these sandbanks comes mainly from the Waikato River. Sand discharged from this river is transported northward by the prevailing coastal currents. Some of this sand is carried into the Kaipara harbour entrance, but mostly cycles out again and then continues moving northwards along the west coast. The southern sandbanks at the entrance are constantly accumulating and releasing this sand. For this reason, a lighthouse was built in 1884 at the end of the Pouto Peninsula, on the northern side of the entrance. It was automated in 1947 and closed in the mid-1950s. The structure still exists and was renovated in 1982–84. The remains of wrecks still become visible under certain tidal and sand conditions. The Kaipara is rarely used today for shipping, and no large settlements lie close to its shores, although many small communities lie along its coastline.
Geology
The Kaipara Harbour is a drowned river valley system, which first formed 2–3 million years ago as an open bay, becoming a sheltered harbour as elongated sand dune barriers formed at the harbour's mouth. Over the last two million years, the harbour has cycled between periods of being a forested river valley and a flooded harbour, depending on changes in the global sea level. The present harbour formed approximately 8,000 years ago, after the Last Glacial Maximum.
Māori settlements and marae have been scattered around the harbour margins for hundreds of years. The waterways of the Kaipara provided, and still provide, Māori with resources and a ready means of moving between marae.
European history
thumb|Chart of New Zealand, explored in 1769 and 1770 by Lieut. James Cook, commander of the barque Endeavour. Shows the Kaipara Harbour as "False Bay".
thumb|The three-masted barque Anglo Norman went aground on [[Pouto Peninsula near the harbour entrance in 1914]]
James Cook sighted and recorded the harbour on his first voyage, in 1770. He named it "False Bay", noting in his journal that it had "the appearance of a Bay or inlet, but I believe it is only low land".
In 1839, European settlers began arriving in the Kaipara to fell and mill kauri trees and build boats for local requirements. The first sailing ship wrecked at the entrance to the harbour was the 550-ton barque Aurora in April 1840. The brigantine Sophia Pate was wrecked at South Head in August 1841 with the loss of all 21 on board. The most recent wreck was the yacht Aosky in 1994.
The Kaipara River is the principal river feeding Kaipara Harbour from the south. From 1863 Helensville established itself as a timber port on this river, and provided shipping services about the Kaipara. When the timber ran out, Helensville developed sheep and dairy farms, and more recently nut plantations, vineyards and deer farms. The Kaipara is the largest estuarine harbour on the west coast of New Zealand and provides significant areas of suitable breeding grounds and habitats for juvenile fish. It has fewer problems with water quality than the Manukau, and is the single most significant wetland for west coast fisheries.
Early versions of oyster farming occurred between the early 1900s and 1950s. Thousands of tons of rocks were placed along the shorelines to act as an additional substrate on which the natural rock oyster could grow. In 2002, the Crown settled the historical claims of Te Uri o Hau, a hapū of the northern Kaipara Harbour. As part of the settlement, access to and the rights of the hapū to gather oysters within the existing "Maori Oyster Areas" were recognised. In 2008, resource consent was given to Biomarine to establish New Zealand's largest oyster farm in the Kaipara. The farm is projected to produce about NZ$30 million in annual exports and 100 new jobs.
In recent years, there has been a perception amongst locals that commercial fishers have damaged fisheries in the Kaipara. Locals have been frustrated in their attempts to gain government support. The veteran filmmaker Barry Barclay has examined this in his 2005 documentary, The Kaipara affair.
Sand mining
Currently (2007) about 219,000 cubic metres of sand is mined each year from the entrance and tidal deltas of the Kaipara. This sand contributes over half the sand requirements for Auckland. The sand is used in the production of concrete and asphalt, and also in drainage systems and beach nourishment. A suction pump is usually used to extract the sand from the seabed. It is pumped into a barge as a sand and water slurry. As the barge loads, shells and other objects are screened out and the sea water drained back to the sea. The availability of sea sand within the Auckland region means the road costs of transporting sand from further parts of the country are avoided. Concerns about possible negative consequences of this sand mining have also been raised.