Maitai River

The Maitai River (also known as the Mahitahi River) is Nelson's largest river located in New Zealand's South Island, located on the islands North-West peak [1]. The river stretches from the Bryant Range, situated to the east (inland) of the coastal city Nelson, where it flows towards the city, flowing west through the heart of the city and into the Tasman bay at Nelson Haven[1]. The catchment of the river covers some 9000 hectares, and has two branches in the upper catchment, the north meets a dam, where the south travels west into the middle catchment, from where it takes its final journey through the urban area of the city before meeting the ocean[1].

Maitai River
Water behind the dam on the river
Location
Country	New Zealand
State	Nelson
Physical characteristics
Mouth
• location	Tasman Bay
Length	11 km (7 mi)
Basin size	9000 Ha
Discharge
• minimum	190L/s
• maximum	400L/s

The Maitai river provides habitats for a plethora of diverse wildlife, at all catchments of the river and its surrounding ecosystems. This sees that many species of bird, fish, mammals and reptiles use the river as both a home and a source of food and drinking water, as well as for extensive amounts of vegetation to grow around the abundant water-source[1]. There has also been discoveries of unique life in the Maitai River as well as surrounding rivers in the Nelson region.[2]

Social and leisure uses for the river range from walking trails to swimming holes, where either the river's water that meets the city is used by the population, or its inhabitants walk upstream towards a less urbanized section of the river.[3] Walking trails cover majority of the entrance of the river to the city, creating a source of exercise for the residents of nelson and surrounding homes[3]. There are also tourist and leisure spots and activities that use the river.[4]

The river is also utilized by the council and government in more economic and resource management ways, where a dam and reservoir[5] has been placed on the river as well as the water from the river is used to supply the neighboring city of Nelson with water[6]. The river is also used as a storm-water channel and flood channel for Nelson City as well[4].

Geography

Further information: Nelson, New Zealand

Maitai River

Being the largest river in the Nelson region, the Maitai river is stretches a long distance of 11 kilometers, flowing into the Tasman sea from the Bryant Range.[7] The Maitai river also includes smaller rivers which are tributaries to the main westward flow of the river.[7] These tributaries are considered part of the river; the two mains ones are the Mineral Belt and Roding[7]. Because of the inland nature of the river, once it extends past the urbanized area of the city and more into the east, the river is surrounded by a vast amount of forest and rock-face, where water is channeled into the river.[7] Further upstream, the river meets the Maitai Dam and Reservoir, which is the furthest upstream man-made feature on the river.[6] A layer of thick rock prevents the river from joining with the neighboring rivers and waters[2] on its eastern side.

The river starts at the Headwaters, where it flows down to the Lowland Hill Country, which is the largest section of the Maitai river, consisting mostly of forest.[1] From there it flows further northwest towards the ocean, as it becomes the Lowland Flats and Allulvai Terraces, which is also mostly forest, but sitting atop flat lands.[1] It then reaches the Coastal Flats, where it meets the ocean, and is the last of the forest land that surrounds the river before it meets the city.[1] The river's mouth opens into the Tasman Sea at Nelson Haven, where the estuary is surrounded by some urbanized areas.[1]

Wildlife

Due to the vastness of the river, the Maitai River is host to a wide range of both flora and fauna, dependent on where they live along the river, both in the water and beside.

Fauna

See also: Fauna of New Zealand

The fauna surrounding and living within the river are typically dependent on the river as a means of both shelter and water and food, creating its own unique ecosystem. Where the river opens to the sea, there is an abundance of estuarine creatures, here fish and seabirds thrive, as well as crustaceans, sharing wildlife with the Nelson Haven which the river opens into.[1] Shorebirds such as the Red Knot and oyster catchers appear here in abundance.[1] As the river continues east, the estuary become less saline and joins with the freshwater river. Here wildlife can be seen that are typically rare, such as birds like the Rifleman and Kakariki, who live in the forests surrounding the river.[8] Other animals that use the river and its surrounding forests are reptiles like the Forest gecko and Northern grass skink, as well as invertebrates like the Giant land snail.[8] Fish populations that live in the Maitai River consist of fish that are unique to New Zealand and the Nelson region, such as the Inanga, Longfin eel and Brown trout.[1] There have also been discoveries within the waters, such as new species of water-beetles in the river, that use the unique ecosystem of the river to survive.[2]

Flora

See also: Flora of New Zealand

Maitai Crown Fern

Plants and vegetation rely heavily on the geography of the land surrounding the river, as well as the mineral and soil quality of the adjacent ground. As the river leads the city,and the river maintains somewhat close proximity to the city, it is lined by podocarp forests, which change as you follow the river eastward, where there is more of an abundance of beech vegetation due to the change in soil quality.[1] Further East it is met by an abundance of tributaries, one of which, the mineral belt, has a unique soil, where very specialized flora is able to grow, making them both endangered and rare species[1]. The lowland hill country ecosystem located around the river is covered in vegetation where the land slopes, where beech, podocarp and kamahi foliage grows in abundance.[1]

Lifestyle and leisure

The Maitai River is used commonly and recreationally by both the people of Nelson and tourists, due to its proximity to the city and significance.[1] Walking trails are common and line the river, typically starting at the city and then working their way east towards the Ranges, taking upwards of a few hours to complete.[3] These trails are also existent within and just outside the city, where cycling and running is encouraged.[3] These trails are lined with swimming holes, where those who visit are able to swim in the river itself.[3] There are multiple swimming holes that go not only around the river near the city, but also further up the river[4] which provide the residents and tourists with many options for enjoyment. Other leisure activities and practices surrounding the river include fishing and water activities, where the estuary provides access into the sea for a greater exploration of the river and its ecosystem.[9] The river is also home to Golf courses, which use the river as both an attraction and a water source, providing recreational activity to those who live nearby.[4] Camping and exploration are also common around this area, where places such as the Maitai Valley Camp, provide spaces for people to live in the splendor of the river.[4] Cycling and biking trails also follow the river and its extremities.[4] Leisure activities can be halted in the river in certain season due to changes in the river, whether it was the growth of algae or the imbalance of minerals in the river itself.[4]

Economic and Resource Uses

The Maitai River is a vital part of Nelson city's water, as it provides a large amount of usable water to the region.[6] This water that the city uses comes from the Maitai as well as other sources, where the Maitai became vital after the introduction of the Maitai Water Supply Project.[6] This project saw the increase of water storage capacity in the river that was to be used as a resource to the city, by almost more than double.[6] The project saw the Maitai Dam and Reservoir were placed in the river in order to increase the storage capacity of Nelson City's water.[6] The project also planned to provide the city with high quality water, without treatment more than chlorination.[6] Plans and studies to implement these were started in 1980, and it took 49 months for these plans to be finalized and actualized, where final planning and designing began in April 1984, finishing approximately in the middle of 1986.[6] Management of the water can prove difficult as the water fluctuates in both temperature and water quality, seen in effects such as the thermal stratification that can occur in the summer.[10] Moreover, micro-bacteria and other concerns need to be managed within the river in order to ensure that the water maintains drinkable and usable buy the population and council of Nelson.

The river also has a dam, placed higher in the system towards the upper catchment which alters and impacts the fauna and flora of the area, as well as the flow of the river.[1] This damming creates the Maitai Reservoir[1], which is capable of 50,000 meters cubed of water.[6] This water supply is the main source of water for the city of nelson so it is vital to the population that it is maintained and usable for the benefit of all around it.[4] The dam and reservoir are expansive, where it covers approximately 32Ha of space, and sinks to 32.75m vertically down, allowing it to hold almost 4Mm³ of water to provide to the city.[4] The reservoir is used to refill the dam when it is running low on water, however it is also used when regular conditions are in effect, returning water to the dam in need. [10] The water quality of the dam and reservoir are constantly tested and monitored in order to determine the safety of the water to be used by the population for drinking or other household uses.[5] These are implemented to ensure that the city is protected from flooding and to redirect the water to refill the dam if it is in need of water.[10]

The Maitai river acts as a storm-water and flood channel which provides protection and also water to the city.[4] These water and flood channels are utilized in a way to stop flood water from damaging properties and infrastructure within and surrounding Nelson City.[4] These also work as a storm water drainage system, which helps the flow and the management of water in the river and city.[4]

Forestry and Plantations are also used around the Maitai River, which provides the water for the trees to grow.[7] The mid-catchment area is also utilized as a place for plantations of pine trees. [4]

References

1. "Story Map Series". nelsoncity.maps.arcgis.com. Retrieved 23 April 2020.
2. Ordish, R. G. (March 1976). "Two new genera and species of subterranean water beetle from New Zealand (Coleoptera: Dytiscidae)". New Zealand Journal of Zoology. 3 (1): 1–10. doi:10.1080/03014223.1976.9517892. ISSN 0301-4223.
3. "Maitai River Walkway - Nelson City". Nelson Trails. Retrieved 23 April 2020.
4. Martin, J. (March 2020). "Iconic urban waterway and storm-water channel: Reviving the Maitai Channel". waternz. Retrieved 23 March 2020.
5. Marsay, Becky (June 2016). "Influences of changes of Maitai Dam operations on the water quality in the Maitai River and Reservoir" (PDF). nelson.govt. Retrieved 19 March 2020.
6. Pickens, G. A. (1989). "The Maitai Water Supply Project". IPENZ Annual Conference 1989, Proceedings of: Engineering our natural resources; Papers prepared for the conference, Dunedin, February 13-17 ; Civil, general and electrical, mechanical, chemical: 163.
7. Miskell, Boffa (2016). "Nelson Landscape Study 2016: Landscape Evaluation" (PDF). www.nbus.co.nz. Retrieved 20 March 2020.
8. "Animals - Nelson City Council". www.nelson.govt.nz. Retrieved 25 May 2020.
9. "Maitai River". nzfishing.com. Retrieved 24 April 2020.
10. Holmes, Robin (October 2012). "Options for Improving Water Quality in the Maitai River and Reservoir" (PDF). Cawthorn. Retrieved 23 May 2020.

"Place name detail: Maitai River". New Zealand Gazetteer. Land Information New Zealand. Retrieved 12 July 2009.