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Current state vs freshwater objectives: E. coli

Description

Comparison of Escherichia coli to NOF C-band in New Zealand’s river receiving environments.

The dataset contains the following attributes for rivers and watersheds:

  • the predicted current state as defined by the E. coli median statistic
  • the predicted current state as defined by the E. coli Q95 statistic
  • the predicted current state as defined by the E. coli G260 statistic
  • the predicted current state as defined by the E. coli G540 statistic

  • the predicted current yield of E. coli giga E. coli/hectare/year
  • the estimated local excess yield of E. coli giga E. coli/hectare/year

  • the probability that the current state as defined by the E. coli median statistic is compliant with the NOF C-band
  • the probability that the current state as defined by the E. coli Q95 statistic is compliant with the NOF C-band
  • the probability that the current state as defined by the E. coli G260 statistic is compliant with the NOF C-band
  • the probability that the current state as defined by the E. coli G540 statistic is compliant with the NOF C-band

  • the load reduction required to achieve at least the NOF C-band (expressed as a yield by dividing by catchment area; giga E. coli/hectare/year) for critical catchments
  • the load reduction required to achieve at least the NOF C-band (expressed as a proportion of current E. coli yield; %) for critical catchments

 

Date: 29 August 2023 Version: v2

Contact: Ton Snelder, LWP Ltd

 

Link to report / paper

 

Our Environment

You can view the data in this dataset on a map-based web app here: E. coli excess load

 

Preview Image

 

Dataset attributes

Spatial extent All NZ
Spatial resolution Based on the digital river network used by the River Environment Classification (REC). This river network is generally consistent with 1:50,000 scale maps.
Temporal extent Nominally 2016 to 2020. This 5-year period was used to esimate current E. coli attribute states.
Temporal resolution Loads are average annual.
Evaluation method (Validation) Individual models were evaluated using bootstrapping or leave-one-out cross validation.
Evaluation result (Numeric) Several measures were used to describe the performance of the models used to predict the current state of the E. coli attribute (i.e.,the four E. coli statistics) and to predict E. coli yields. See report for details.
Evaluation result (Categorical)
Uncertainty method Monte Carlo analysis was used to estimate the overall uncertainties for all segments of the river network.
Uncertainty data format (Numeric) Confidence interval of 90% confidence interval.
Uncertainty data format (Categorical)

 

Methodology

Based on spatial statistical models and a comparison of predicted concentration to criteria defined by the NPSFM E. coli attribute target states.

See Snelder T, Smith H, Plew D, et al (2021) Nitrogen, phosphorus, sediment and Escherichia coli in New Zealand’s aquatic receiving environments. Comparison to national bottom lines. LWP Ltd, Christchurch, New Zealand.

 

Fitness for purpose / limitations

This table indicates whether the dataset is suitable for different types of questions at different scales.

Note: Users should carefully consider their purpose as this dataset may not be suitable.

Operational Absolute Relative Screening/scoping
Block/farm No No No No
Multi-farms(5+) No No No No
Catchment Maybe Maybe Maybe Maybe
National/regional Yes Yes Yes Yes
Caveat(s) The study has used all the available data. Therefore, it would be difficult in most catchments to improve on the analysis. However, because the models were all national in extent, there may be a degree of model bias when the results are applied at fine scales.

Data and Resources