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The Waipa River is in the Waikato region of the North Island of New Zealand. The headwaters are in the Rangitoto Range east of Te Kuiti. It flows north for , passing through Otorohanga and Pirongia, before flowing into the Waikato River at Ngaruawahia. It is the Waikato's largest tributary. Over was navigable by waka and Pirongia (Alexandra) was busy as the head of steamboat navigation until the railway was built to Te Awamutu in 1880. However, a 1915 guidebook still said, "Small steamers ply up and down the river from Huntly".〔The Raglan and Kawhia Districts: E E Bradbury 1915 page 49〕 An 1881 article said a journey upriver would normally take 36 hours, but more in dry weather, when shoals at Whatwhata and Te Rore were hard to cross.〔(Waikato Times, Volume XVI, Issue 1375, 26 April 1881, Page 3 )〕 In the headwaters upstream of Otorohanga the river can be very clear during low flow conditions. This section of the river flows through rough farmland and patches of native bush. In this clearer part of the river there can be very good fly fishing for trout, but you'll need to ask the land owners permission to access the river. The Waipa is prone to flooding in its lower reaches as flood flows can be over 100 times——those of dry flows and the river can rise up to .〔http://www.waikatoregion.govt.nz/riverlevelsandrainfall/cgi-bin/hydwebserver.cgi/points/details?point=35&catchment=17, http://www.waikatoregion.govt.nz/riverlevelsandrainfall/cgi-bin/hydwebserver.cgi/points/details?point=939&catchment=17, http://www.waikatoregion.govt.nz/riverlevelsandrainfall/cgi-bin/hydwebserver.cgi/points/details?point=28&catchment=17 and http://www.waikatoregion.govt.nz/Services/Publications/Technical-Reports/Waikato-and-Waipa-rivers-flood-event-6-16-July-2002/〕 ==Pollution== Waikato Regional Council measures water quality monthly at five sites from Mangaokewa to Whatawhata.〔(map of pollution monitoring sites. )〕 The measurements show poor quality along most of the river, with excess nitrogen, silt and phosphorus, though E. coli levels have improved with improved sewage treatment, though generally not enough for safe swimming.〔http://www.waikatoregion.govt.nz/Environment/Natural-resources/Water/Rivers/Waipa-River/Trends-in-Waipa-River-water-quality/〕 Nitrogen levels increased at all five sites between 1993 and 2012 due to intensified land use.〔(Trends in Waipa River water quality )〕 Ministry for the Environment figures〔http://www.mfe.govt.nz/publications/water/water-quality-trends-1989-2007/index.html〕 averaged between 1998 and 2007 showed the Waipa at Otorohanga had 280 E.coli per 100ml (53rd worst out of 154), 360 faecal coliforms per 100ml (83rd of 252), 0.55mg/litre nitrogen (161th of 342) and 0.03mg/litre phosphorus (187th of 361). At Pirongia the figures were 390 E.coli per 100ml (35th worst out of 154), 425 faecal coliforms per 100ml (64th of 252), 0.49mg/litre nitrogen (174th of 342) and 0.06mg/litre phosphorus (80th of 361). At Whatawhata the figures were 0.92mg/litre nitrogen (94th of 342) and 0.06mg/litre phosphorus (69th of 361). In the Mangaokewa stream 0.02mg/litre phosphorus (237th of 361). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Waipa River」の詳細全文を読む スポンサード リンク
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