Waingaro River (Waikato)

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

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.

Waingaro River
Waingaro Landing and mangroves at mouth of Waingaro River
Location
Country	New Zealand
Physical characteristics
Source
• elevation	150 m (490 ft)
Mouth
• location	Raglan Harbour
• elevation	0 m (0 ft)
Length	18 km (11 mi)
Basin size	123 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

• List of rivers of New Zealand