Waipa River

Waipa River
From Waingaro Rd bridge looking north down Waipa River to Ngaruawahia Point bandstand, the Waikato (coming from right) and the Hakarimata Range in the background (19-9-2012)
Basin
Main source	Rangitoto Range
Source elevation	703 m (2,306 ft)
River mouth	Waikato River
Mouth elevation	20 m (66 ft)
Basin area	3,050 km2 (1,180 sq mi)
Country	New Zealand
Length	115 km (71 mi)
Avg. discharge	83.9 m3/s (2,960 cu ft/s)

The Waipa River - The Waikato's largest tributary

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 115 kilometres (71 mi), passing through Otorohanga and Pirongia, before flowing into the Waikato River at Ngaruawahia. It is the Waikato's largest tributary.

Over 50 kilometres (31 mi) 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.^[1] However, a 1915 guidebook still said, "Small steamers ply up and down the river from Huntly".^[2] 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.^[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—20 to 560 cubic metres per second (710 to 19,780 cu ft/s)—those of dry flows and the river can rise up to 11 metres (36 ft).^[4]

Pollution

Waikato Regional Council measures water quality monthly at five sites from Mangaokewa to Whatawhata.^[5] 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.^[6] Nitrogen levels increased at all five sites between 1993 and 2012 due to intensified land use.^[7]

Ministry for the Environment figures^[8] 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), 0.55 mg/litre nitrogen (161th of 342) and 0.03 mg/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), 0.49 mg/litre nitrogen (174th of 342) and 0.06 mg/litre phosphorus (80th of 361).

At Whatawhata the figures were 0.92 mg/litre nitrogen (94th of 342) and 0.06 mg/litre phosphorus (69th of 361).

In the Mangaokewa stream 0.02 mg/litre phosphorus (237th of 361).

Bridges

Listed in order from the confluence with the Waikato and moving south they are:-

Looking south from Whatawhata bridge

• 1898 Ngaruawahia bridge opened. Collapsed under a mob of cattle 20 December 1916 (see 1917 photo) and rebuilt in 1918.^[9] The bridges were preceded by a punt, supplied by the government in 1887.^[10]
• 1914-1958 Waipa Railway and Coal Co. 21 metres (70 ft) long^[11] bridge.
• 1881 (20 April) 160 metres (520 ft) long Whatawhata bridge originally. The wooden structure 15 ft (4.6 m) above high water mark^[12] consisted of two spans of 24 metres (80 ft), 7 of 40 and 4 of 6.1 metres (20 ft), and cost £3700. Repairs were done in 1909, but was in poor repair again by 1917. For £11,250 a new truss bridge was built over the top of it in 1924.^[13] The current concrete bridge, which is south of the original site, was shown on the 1974 edition of the 1 inch Lands & Survey map, but not on the 1965 3rd edition.

Te Rore bridge from south

• 1881 (12 August) 120-metre (400 ft) long Te Rore bridge. Replaced 1957.^[14]
• 1865 (about) Alexandra Bridge, Baffin St, Pirongia, originally built by the army.^[15]
• 1882 Alexandra Bridge, McClure St, Whatawhatahoe, Pirongia."Mr. Wright has superintended the construction of the Alexandra Bridge, over the Waipa River, to give access to Tāwhiao's new settlement, Whatawhatahoe (see map), and which will at the same time eventually be on the main line leading into the King country. The bridge will be open now in a fortnights' time, it consists of six 7.3-metre (24 ft) spans, and three 12-metre (40 ft) trusses, a total length of 80 metres (264 ft), the height being 13 metres (42 ft) above ordinary river level. The approaches and about a mile of road, and a large culvert have been made by Mr. Wright, with Maori labor. The whole will have been completed at a cost of about £1,800."^[16] There was a plan to replace it in 1939.^[17]
• 1915 Te Kawa Rd bridge 100 metres (340 ft) long, 12 metres (40 ft) high.^[18]
• Kawhia Rd, Otorohanga
• Maniapoto St, Otorohanga photo about 1910
• 1887 North Island Main Trunk railway bridge.
• 1928 Toa Bridge, Otewa Rd.^[19]

External links

• Regional Council summary of information about the river.
• Regional Council water quality information at Whatawhata, Pirongia, Otorohanga, Mangaokewa and water temperature at Otorohanga.
• Encyclopaedia of New Zealand short history
• Lower Waipa flood control scheme
• 1910 photos of Waipa Bridge at Ngaruawahia - , and .
• Geological maps - 1925 Ngaruawahia, Whatawhata-Te Pahu, Pirongia, 1940 Otorohanga, upper Waipa and Pakaumanu.
• 1:50,000 map of source of Waipa River

References

Coordinates: 37°41′S 175°09′E / 37.683°S 175.150°E / -37.683; 175.150