Waingaro River (Waikato)

The Waingaro River is a river of the Waikato region of New Zealand's North Island. It flows generally southwest from its origins near Glen Afton and Glen Massey, west of Ngāruawāhia, to reach a northern arm of Raglan Harbour (see 1:50,000 map). Its main tributary is Kahuhuru Stream, which Highway 22 follows for several kilometres. Tributaries total about 170 kilometres (110 mi).[1] At Waingaro it is fed by a hot spring.

For the river in the South island, see Waingaro River (Tasman).

Waingaro River
Waingaro Landing and mangroves at mouth of Waingaro River
Location
CountryNew Zealand
Physical characteristics
Source 
 • elevation150 m (490 ft)
Mouth 
 • location
Raglan Harbour
 • elevation
0 m (0 ft)
Length18 km (11 mi)
Basin size123 km2 (47 sq mi)

Geology
Waingaro River and hot water pump station - the pool was north of the road, but water is now pumped under the road.

The lower river flows over Puaroan age (about 150 million years ago), blue-grey Puti siltstone.[2]

Pollution

The Waingaro River is one of the largest sources of sediment in Whaingaroa Harbour, partly because it is 99 percent unfenced.[3]

Pollution has been worsening for phosphorus, though nitrogen has improved, as shown in this table of important (i.e. slope direction probability over 95% and RSKSE over ±1% pa) improvements, or deteriorations (-) in relative seasonal Kendall slope estimator (RSKSE) trends (monthly records are flow-adjusted using a Lowess curve fit with 30% span.) -[4] Turbidity is also poor.[5]

% per year Nitrate-N Total phosphorus Dissolved reactive P
1993–2017 1.0 -1.0 -1.0
2008–2017 -3.4

See also

References
  1. Land Air Water Aotearoa
  2. Geology of the Raglan-Kawhia Area: Institute of Geological & Nuclear Sciences (N.Z.), Barry Clayton Waterhouse, P. J. White 1994 ISBN 0-478-08837-X
  3. Regional Council report on Whaingaroa Harbour Care
  4. Vant, Bill. Waikato Regional Council Technical Report 2018/30 Trends in river water quality in the Waikato region, 1993-2017.
  5. "Waingaro River (Pukemiro) at Ruakiwi Rd Off SH22 River Quality". Land, Air, Water Aotearoa (LAWA). Retrieved 18 January 2019.
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