| Kaiwharawhara Stream | |
| Name Etymology: | Maori meaning "food of the fruit of the Astelia" |
| Subdivision Type1: | Country |
| Subdivision Name1: | New Zealand |
| Subdivision Type2: | Region |
| Subdivision Name2: | Wellington |
| Subdivision Type3: | City |
| Subdivision Name3: | Wellington |
| Source1: | Zealandia (wildlife sanctuary) |
| Mouth: | Wellington Harbour |
| Mouth Coordinates: | -41.2618°N 174.791°W |
| Mouth Elevation: | Sea level |
The Kaiwharawhara Stream is a stream in the North Island of New Zealand – it flows through the northwestern part of New Zealand's capital, Wellington. Its headwaters lie within the suburb of Karori, and it passes through other suburbs and Otari-Wilton's Bush before reaching the western shore of Wellington Harbour in Kaiwharawhara near the terminal of the Interislander Ferry. Part of its length runs roughly alongside the Johnsonville Branch railway, a branch line that once formed part of the North Island Main Trunk Railway – the latter now passes over the stream near its mouth.
Its main tributary is the Korimako Stream (which flows from Khandallah and Ngaio), though it is also fed by other tributaries, and its catchment covers roughly 19km2. Much of this area consists of parkland and other reserves, though the water suffers from pollution in the form of stormwater and runoff associated with urban land-use.[1]
The Kaiwharawhara name is from kai, the Māori word for food, and wharawhara, the edible fruit of Astelia Banksii. It is piped along six sections, the main length being 846m (2,776feet), under the former landfill at Ian Galloway Park, from Zealandia (wildlife sanctuary) to Otari-Wilton's Bush. Near its mouth at Kaiwharawhara, a 107m (351feet) tunnel was built as an air-raid shelter in 1944 and the stream was diverted through it after the war, to improve flood protection and allow for additional oil storage tanks.[2]
Fish in the stream include shortfinned eel, longfin eel (ōrea), giant kōkopu, kōaro, banded kōkopu, īnanga, shortjaw kōkopu, common bully (toitoi), giant bully (tītarakura), bluegill bully, redfin bully, goldfish, koi carp, perch and brown trout.[3]
About 20% of the catchment is predominantly in native vegetation, which includes karaka, parviflora var. arborea (koromiko-taranga), makomako, melicytus ramiflorus (mahoe), phormium tenax (harakeke) plagianthus regius (manatu), pohutukawa, pteridium esculentum (aruhe), rangiora, taupata, toetoe and veronica.[4]
Weeds in the valley include paraserianthes lophantha (brush wattle), cytisus scoparius (broom), fennel, gorse, pampas grass, rapeseed, tradescantia fluminensis and tree lupin.
As noted above, the stream passes through a disused landfill and has other pollution sources. The stream mouth has lead and zinc pollution. It is in the worst 25% of all sites across the country for E. coli and very likely degrading. A 5-year median for clarity is 3.34m (10.96feet) and likely improving. Similarly turbidity 5-year median is 1.26 NTU and improving, as is Total Nitrogen with a 5-year median of 1.2 mg/L. The 5-year median of Total Oxidised Nitrogen is 1 mg/L. Dissolved Inorganic Nitrogen has a 5-year median of 1.01 mg/L, Ammoniacal Nitrogen, 0.006 mg/L, Nitrate Nitrogen, 1 mg/L, Dissolved Reactive Phosphorus, 0.0355 mg/L, Total Phosphorus, 0.048 mg/L, MCI, 96.6, QMCI 1.76, ASPM, 2.130, Taxonomic richness, 26, EPT richness 31%.[5]
Several tracks pass through the valley, including Te Araroa long distance trail, which uses the Northern Walkway from Cummings Park via the Korimako valley and then a short length beside the Kaiwharawhara to Wadestown.[6] The Sanctuary to Sea walkway uses most of the valley.[7]