Waikato and Waipa Rivers

Figure one: Source: Waikato Regional Council.

Two major rivers of the Waikato Region are the Waipa and Waikato rivers. The Waipa extends 115km in length from Otorahanga in the south to Ngauruawahia in the North. The Waikato river originates at Lake Taupo in the south, extending 425km to the mouth of the river in Port Waikato to the north. Both of these rivers pass through central and northern sections of the region where landuse for dairy farm has intensified since the 1950’s. This intensification of the land has resulted in the pollution of the lower sections of both the Waipa and Waikato rivers. 

Nitrogen sourced from Nitrates has been cited as a major pollutant within both of these rivers. According to the Waikato Regional Council (WRC) pollution from non-point source origins (dairy and agricultural land runoff) can be attributed to at least 70% of the total pollutants within the Waikato river as shown in figure one.

Figure two: Showing Nitrogen levels within the Waipa and Waikato rivers. Source: Waikato Regional Council.

Table one: This shows the state of improvement/ deterioration of pollutants at monitoring sites. Source: Waikato Regional Council.

In order to manage and limit the amount of pollution, and to prevent the growth of algae within the rivers, the WRC have set a total nitrogen level baseline that should not be exceeded at 0.5grams/m³. As figure two shows, this has been exceeded by 80% of monitored sites on the Waipa and 30% of monitored sites on the Waikato. These surpasses in limits are attributing to the long term degradation of the Waikato regions overall water quality, as both of these rivers serve as tributaries to many thousands of smaller waterways within the region. Evidence provided by the WRC, shows that the pollution of both rivers is increasing in the detrimental direction. Most other indicators show that the Regional council is progressing in some areas of pollution, however when it comes to Nitrogen as is shown in table one.

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Sources: 

Waikato Regional Council - http://www.waikatoregion.govt.nz/