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 Papanui Stream. Specific targets are based on national guidelines and local aspirations. The results here are preliminary - contact the Regional Council if you require more information.
Our water quality dashboard shows the state of specific locations, relative to local and national targets. Currently this includes Papanui Stream (Tukituki catchment).
The results of monthly ecological health monitoring for 80+ Hawke's Bay sites is at LAWA. In the summer months we publish information on “Can I Swim Here?”
To give the dashboard some context, dissolved oxygen supports aquatic insects and fish. Dissolved oxygen is influenced by temperature, river flow, and the amount of nutrients. The condition of these indicators is given as traffic lights. A green light means that life-supporting capacity is good, red/ orange means aquatic life is under pressure. The dashboard also includes measures of management activities such as farm plans.
These are catchment scale targets not national ones, see LAWA for national targets. The targets featured in this dashboard are the most relevant to the Papanui catchment. In accordance with national guidance E. coli, DIN and DRP data are collected monthly, and macroinvertebrates are collected annually.
No Plan Target
This is 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 Papanui reflect poor water quality (e.g. low dissolved oxygen) and degraded habitat, characterised by excessive weed and sediment.
We use E. coli as an indicator of faecal contamination from warm bloodied animals. Not all strains of E. coli are hazardous; however, high concentrations suggest that other pathogens maybe present.
River flow has a strong influence on water quality and ecology. High flows are associated with increased sediment loading and associated contaminants.
Heavy rain events wash animal faecal matter into the stream. Spikes in E. coli (and turbidity) suggest that for the majority of the catchment, the margins of the Papanui stream are not an effective filter for run-off.
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.
During the summer months, excessive DIN is absorbed by weeds and changed into other forms of Nitrogen by warm temperatures.
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 green line at the bottom of the graph represents the plan target for the Papanui catchment (0.8mg/L). Various land use activities are likely to be contributing to these high levels.
This is live data recorded multiple times per day. There are no targets for these measurements; however these graphs give an indication of how quickly important aspects of river condition can change.
There are many direct and indirect ways in which temperature can influence aquatic life. For example, warmer temperatures decrease the oxygen carrying capacity of water, and increase the metabolic rates of all forms of life. Oxygen is produced by plants during photosynthesis. However, it can be severely reduced by certain types of pollution (e.g. organic). The percentage saturation of dissolved oxygen is water is a useful measure of ecological health. For rivers throughout Hawkes’s Bay water temperature and dissolved oxygen levels drop overnight.
Saturated oxygen levels in the Papanui are generally too low, and temperatures too high. This is due to a combination of issues located within the stream (e.g. low flow), the river margins (e.g. lack of shading), and land use. Large fluctuations in oxygen and temperature over a period of 24 hours are particularly stressful. Extensive stands of exotic weeds contribute to this by generating oxygen during daylight hours, and depleting it during the night.
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. Turbidity in shallow rivers such as the Papanui has a relatively weak influence upon plant growth. 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.
Turbidity in shallow rivers such as the Papanui has a relatively weak influence upon plant growth. 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.
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