The Regional Council is working with farmers and community groups to improve the health of our local rivers and lakes. We aim to reduce nutrient levels, such as phosphorus, in the Mangaonuku catchment. Specific targets are based on national guidelines and local aspirations. The results here are preliminary - contact the Regional Council if you require more information.
We have developed dashboards for all the Tukituki sub catchments to help landowners find out about the ecosystem health of their sub-catchment, and identify whether they require a resource consent.
If you have any questions about resource consents, please contact one of our Consent Advisors – 06 833 8090, email: firstname.lastname@example.org
Latest Water Quality Information
The targets featured in this dashboard are the most relevant to the Mangaonuku catchment, and these are catchment scale targets, not national ones. See LAWA for national targets. In accordance with national guidance E. coli, DIN and DRP data are collected monthly, and macroinvertebrates are collected annually.
No Plan Target
These are determined using a 5 year rolling average of values. But red/green shaded areas on the graphs are used to put individual values/samples into context - if the majority of samples are in red then the site will fail to meet the plan target.
Aquatic macroinvertebrate communities are at the centre of aquatic food webs, and link the energy of the sun to fish and birds. They respond to a combination of water quality, habitat (including river flow), and climate.
We report upon macroinvertebrates by calculating the Macroinvertebrate Community Index (MCI). The MCI assigns a score to each species or taxon (1 to 10), based on its tolerance or sensitivity to organic pollution, and then calculates the average score of all taxa present at a site. Increases in MCI are generally considered to be good.
Macroinvertebrate communities of the Mangaonuku are considered 'fair', and reflect moderately degraded habitat and instream conditions. Improving riparian protection, planting trees to shade waterways and reducing erosion will usually help MCI the most.
An essential element for plant growth but elevated levels can lead to excessive plant and algal growth with associated problems. It is readily transformed between soluble and insoluble forms. The graph represents changes in Dissolved Inorganic Nitrogen (DIN) which is the form of nitrogen available for aquatic plant and algae growth. The Tukituki Catchment Plan has set a limit of 0.8 mg/L for the Mangaonuku Catchment.
The concentrations of DIN in the Mangaonuku are amongst the highest in the Tukituki, and all of Hawke's Bay. Mitigations to reduce nitrogen levels are a very high priority for this subcatchment. Constructed wetlands may be an effective approach if other on-farm approaches are insufficient.
We measure a particular form of phosphorous - Dissolved Reactive Phosphorous (DRP) because this is the only form available for aquatic plant and algae growth. Phosphorous is an essential element for plant growth but elevated levels can led to excessive plant or algal growth with associated problems. Over time, phosphate bound to sediment (soil particles in the water) dissolves and becomes DRP.
The Mangaonuku is not meeting the relevant plan target for DRP (0.010mg/L). Elevated phosphorus can be due to a variety of sources, but often relates to erosion and overland flow from critical source areas. Protecting wide buffers around riparian areas can help prevent phosphorus entering waterways.
Rolling median: 1.14mg/L - NB the calculated median is calculated from both FNU and NTU data, so should be treated with caution.
Increases in turbidity are associated with elevated sediment loading which is often caused by erosion. River flow has a strong influence on turbidity and other aspects of water quality. High flows are associated with increased sediment loading and associated contaminants. The relationship between turbidity and rainfall/river flow is a complex one. During heavy rain solids are washed into the stream but there is also more dilution. Compared to large powerful rivers like the Tukituki, the fine sediment and organic matter is more likely to settle on the bed of the Mangaonuku. Sedimentation reduces habitat quality, and limits the type of animals that can live in the waterways.
Extremely high turbidity occurs on high flows in the Mangaonukuand represents the large sediment load being transported downstream by waterways in the Tukituki. Reducing hill country erosion, and protecting and stabilising stream banks, should be a priority for landowners in this catchment.
Values displayed on this page are from automated calculations. They are intended as a guide only. Please seek confirmation from the regional council for verified values needed for consent or compliance purposes.
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