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Ashley River at Gorge Bridge

The Ashley Gorge is situated a short distance from Christchurch, in the hills in the Oxford district.

 

This site is monitored for both water quality and ecosystem health and is located within a popular picnic and camping area at the base of the Mount Thomas forest. There are toilet facilities and a playground in the picnic area. Deep swimming holes along the river attract swimmers.

Recreational water quality at this site is influenced by flow related spikes in E. coli. Swimming at the site is not recommended up to 48 hours after rainfall.

Water Quality
Water quality data for this site
Can I trust this data?

This dashboard shows information on the data collected by the regional councils for water quality indicators, analysed as state and trend.

  • State

    State shows how the median of samples from this site compares to other sites.

    This site is a {{siteDescription}} site. Currently showing the state of this site compared to:

  • The state is also represented by comparison to the National Objectives Framework (NOF) in the National Policy Statement for Freshwater Management 2014  for some indicators.

  • Trend

    Trend shows how the quality of water is changing over time. Depending on the sampling history duration, five, ten and fifteen year timescales are available:

The state is also represented by comparison to the National Objectives Framework (NOF) in the National Policy Statement for Freshwater Management 2014  for some indicators.


Can I trust this data?

The Cawthron Institute has worked alongside regional councils to verify the processes and methods used for data collection, laboratory analysis of samples collected and the statistical analysis and interpretation of the results presented.

If all Cawthron ticks are green, then you can trust this data. However, if one or more ticks are orange, then conclusions should be treated with some caution.

For more details on each tick, see our 'Can I Trust This Data?' Factsheet.

Can I trust the data for this site?
Data Collection

All samples were collected using approved field protocols and have been analysed in accredited laboratories. Therefore the data shown here has been collected and analysed following best practice.

State

All samples were collected using approved field protocols and have been analysed in accredited laboratories.

Trend - SAMPLING FREQUENCY

The majority of trend calculations for this council are based on quarterly data. Sites with more data points generally have greater ‘statistical power’ for trends to be detected. Therefore, any trends shown here have less ‘statistical power’ for trend detection than trend calculations based on monthly sampling which is recommend by Davies-Colley et al. (2012).

Bacteria

E. coli
{{medianValue('ECOLI')}}
State
{{stateMsg(ECOLI.StateScore)}}
State
{{ECOLI.NofBand | uppercase}}
NOF Band
N/A
NOF Band
Trend
{{trendMsg(ECOLI)}}

Sample history at this site

Showing:
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E. coli samples for Ashley River at Gorge Bridge
n/100ml

What is this graph showing me?

This graph is displaying E. coli concentrations over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

What do the icons mean?

The bands for E. coli are as outlined in the NOF for freshwater:

A
For at least half the time, the estimated risk is <1 in 1000 (0.1% risk). The predicted average infection risk is 1%*.
B
For at least half the time, the estimated risk is <1 in 1000 (0.1% risk). The predicted average infection risk is 2%*.
C
For at least half the time, the estimated risk is <1 in 1000 (0.1% risk). The predicted average infection risk is 3%*.
D
20-30% of the time, the estimated risk is >=50 in 1000 (>5% risk). The predicted average infection risk is >3%*.
E
For more than 30% of the time, the estimated risk is >=50 in 1000 (>5% risk). The predicted average infection risk is >7%*.
* The predicted average infection risk is the overall average infection to swimmers based on a random exposure on a random day, ignoring any possibility of not swimming during high flows or when a surveillance advisory is in place (assuming that the E. coli concentration follows a lognormal distribution). Actual risk will generally be less if a person does not swim during high flows.
 Download data

Clarity

Black disc
{{medianValue('BDISC')}}
State
{{stateMsg(BDISC.StateScore)}}
Trend
{{trendMsg(BDISC)}}

Sample history at this site

Showing:
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Black Disc samples for Ashley River at Gorge Bridge
metres

What is this graph showing me?

This graph is displaying Black Disc readings over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

 Download data
Turbidity
{{medianValue('TURB')}}
State
{{stateMsg(TURB.StateScore)}}
Trend
{{trendMsg(TURB)}}

Sample history at this site

Showing:
–
Turbidity samples for Ashley River at Gorge Bridge
NTU

What is this graph showing me?

This graph is displaying Turbidity levels over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

 Download data

Nitrogen

Total Nitrogen
{{medianValue('TN')}}
State
{{stateMsg(TN.StateScore)}}
Trend
{{trendMsg(TN)}}

Sample history at this site

Showing:
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Total Nitrogen samples for Ashley River at Gorge Bridge
g/m3

What is this graph showing me?

This graph is displaying Total Nitrogen concentrations over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

 Download data
Total Oxidised Nitrogen
{{medianValue('TON')}}
State
{{stateMsg(TON.StateScore)}}
Trend
{{trendMsg(TON)}}

Sample history at this site

Showing:
–
Total Oxidised Nitrogen samples for Ashley River at Gorge Bridge
g/m3

What is this graph showing me?

This graph is displaying Total Oxidised Nitrogen concentrations over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

 Download data
Ammoniacal Nitrogen
{{medianValue('NH4')}}
State
{{stateMsg(NH4.StateScore)}}
State
{{NH4.NofBand | uppercase}}
NOF Band
N/A
NOF Band
Trend
{{trendMsg(NH4)}}

Sample history at this site

Showing:
–
Ammoniacal Nitrogen samples for Ashley River at Gorge Bridge
g/m3

What is this graph showing me?

This graph is displaying Ammoniacal Nitrogen concentrations over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

What do the icons mean?

The bands for Ammoniacal Nitrogen are as outlined in the NOF for freshwater:

A
Water quality is considered suitable for the designated use. 99% species protection level: No observed effect on any species tested.
B
Water quality is considered suitable for the designated use. 95% species protection level: Starts impacting occasionally on the 5% most sensitive species.
C
Water quality is considered suitable for the designated use. 80% species protection level: Starts impacting regularly on the 20% most sensitive species (reduced survival of most sensitive species).
National bottom line: Annual median 1.30 mg NH4-N/L. Annual maximum 2.20 mg NH4-N/L (milligrams ammoniacal-nitrogen per litre). Note 1 mg/l = 1 g/m3
D
Water quality is not considered suitable for the designated use. Starts approaching acute impact level (ie risk of death) for sensitive species.
 Download data

Phosphorus

Dissolved Reactive Phosphorus
{{medianValue('DRP')}}
State
{{stateMsg(DRP.StateScore)}}
Trend
{{trendMsg(DRP)}}

Sample history at this site

Showing:
–
Dissolved Reactive Phosphorus samples for Ashley River at Gorge Bridge
g/m3

What is this graph showing me?

This graph is displaying Dissolved Reactive Phosphorus concentrations over the selected time period. You can adjust this period by changing the dropdowns. These records form the basis for the state and trend indicators displayed on the dashboard. This data is raw and has not had any methodology applied to it.

Find out about how State and Trend are calculated.

 Download data
Total Phosphorus
{{medianValue('TP')}}
State
{{stateMsg(TP.StateScore)}}
Trend
{{trendMsg(TP)}}

Sample history at this site

Showing:
–
Total Phosphorus samples for Ashley River at Gorge Bridge
g/m3

What is this graph showing me?

 Download data
Can I Swim Here?
Ecology
Ecological data for this site
Can I trust this data?

This dashboard shows the results from macroinvertebrate sampling at this site.  It displays three ecological indicators: macroinvertebrate community index, taxonomic richness and percent EPT. 

For sites where State is 'N/A' or Trend is 'Not Assessed', there are not enough data to calculate a State and/or Trend result.  Click on an indicator to see the available historical data.

 

Select trend period for MCI

  • 10 years
  • 15 years
  • MCI

    5 year median: {{medians.MciMedian}}

    State

    {{medians.MciState.Text | uppercase}}

    Trend
    {{medians.MciTrend[selectedTrendPeriod].Text}}
    The Macroinvertebrate Community Index uses aquatic macroinvertebrates to assess the health of streams in New Zealand.

    MCI sample history at this site

    Showing:
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    MCI for Ashley River at Gorge Bridge
    MCI score

    What do the icons mean?

    EXCELLENT
    MCI score of more than 119. Streams in excellent ecological condition. Indicative of excellent water quality and/or habitat conditions.
    GOOD
    MCI between 100 and 119. Streams in good ecological condition. Indicative of good water quality and/or habitat conditions.
    FAIR
    MCI between 80 and 99. Streams in fair ecological condition. Indicative of only fair water quality and/or habitat condition.
    POOR
    MCI less than 80. Streams in poor ecological condition. Indicative of poor water quality and/or poor habitat conditions.
  • Taxonomic richness

    The median of the last 5 years of data

    {{medians.TaxaMedian || 'N/A'}}
    Taxonomic richness is the number of different taxa present in an ecological community identified to the best possible level.

    Taxa richness history at this site

    Showing:
    –
    Taxa richness for Ashley River at Gorge Bridge
    Number of taxa
  • Percent EPT richness

    The median of the last 5 years of data

    {{medians.EptMedian}}
    EPT are macroinvertebrates that are sensitive to water pollution. These are Ephemeroptera (mayfly), Plecoptera (stonefly) and Trichoptera (caddisfly).

    EPT history at this site

    Showing:
    –
    Percent EPT richness for Ashley River at Gorge Bridge
    EPT %
Can I trust this data?

The Cawthron Institute has worked alongside regional councils to verify the processes and methods used for macroinvertebrate data collection, processing of the data in the laboratory, quality control in the field and laboratory and the statistical analysis and interpretation of the results presented.

For more details on each tick, see our 'Can I Trust this Data?' Factsheet.

Can I trust the data for this site?
Data Collection

Macroinvertebrates are sampled at this site as part of council's stream health monitoring programme.

Sampling - Frequency

Macroinvertebrate sampling is done annually or more frequently at this site.  Annual sampling provides enough data points for state and trend analyses to be calculated with sufficient statistical power for trend detection.

Sampling - Protocols

This site is a hard-bottomed site and appropriate sampling protocols have been applied.  Data shown here have been collected using current best-practice based on Stark et al. (2001).

Sampling - Habitat

Macroinvertebrate sampling is done in all meso-habitats (i.e., pool, run and riffle), rather than just in riffle habitat, as Stark et al. (2001) suggest. All-habitat sampling provides a more comprehensive description than riffle-only sampling of the invertebrate community at a stream site. However, comparisons made between macroinvertebrate data collected in all habitat and data collected in just riffle habitat need to be treated with caution.

Sampling - Stand-down period

This council does not collect any macroinvertebrate samples for up to two weeks after a flood greater than three times the median flow as recommended by Stark et al. (2001). Therefore, data collected at this site is following best practice.

Processing - Protocol

Samples at this site have been processed following protocol P2 which is recommended by Stark et al. (2001). However, the individual count number has been reduced from 200 to 100 (with a scan for rare taxa).  Data processed at this site are therefore not following best practice and conclusions based on this data need to be treated with caution.

Quality Control - Field

Data collected at this site had some form of field quality control done.

Quality Control - Lab

Data processed at this site has had one of the three Laboratory Quality Control Protocols (i.e., QC1, QC2,Q C3) applied. Data shown here is more robust than data with no laboratory QC applied.
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