Water Nitrate

AUS-TMI-LVG-WNI General Moderate confidence

Benchmark Value

0.7 mg/L
Direction: Lower is desirable ↓
Form: Point

Scoring Curve

Scoring curve unavailable

The scoring engine could not generate a curve for this benchmark context. The primary form is CompositeFramework, but the benchmark data may be missing required fields (e.g., optimal range bounds for an OptimalRange benchmark). This is typically a data quality issue in the benchmark pipeline.

Contributing Benchmarks

CompositeFramework Primary MaximumOnly Guard OptimalRange Guard UpperThreshold Guard OptimalRange Guard MaximumOnly Guard Point Guard MaximumOnly Guard CompositeFramework Guard MaximumOnly Guard Point Guard

Evidence & Context

Therefore, the recommended benchmark is 0.7 mg/L. This value should be interpreted as a target for the event mean concentration in runoff from a best-practice grazing system, with the expectation that ambient baseflow concentrations would be significantly lower.

Metric Definition:

Event mean concentration of nitrate (NO3−N or NOx−N) in runoff from best-practice grazing systems

Benchmark Definition:

This benchmark represents a target concentration for nitrate in runoff from best-practice grazing systems in the Tropical & Subtropical Maritime Islands biome, reflecting a conservative value to protect sensitive marine ecosystems.

Justification:

The reference value is based on a proxy data approach due to a documented lack of direct field measurements for this specific biome and land use combination. The primary data source used for context is the Brigalow Catchment Study, a long-term experiment in a conservatively grazed subtropical savanna catchment, which reported event mean oxidised nitrogen concentrations of 1.7 mg/L. The selected benchmark of 0.7 mg/L is a more conservative value, chosen to account for the exceptionally high ecological sensitivity and direct connectivity to marine ecosystems of the target biome. It aligns with the original (though now superseded for toxicity) ANZECC 95% ecosystem protection guideline value, which is considered more relevant to preventing eutrophication than modern toxicity-based thresholds.

Sources (1)

Preview of Memorandum - Nitrate guideline values in ANZECC 2000, accessed August 8, 2025
Memorandum - Nitrate guideline values in ANZECC 2000, accessed August 8, 2025 Journal

Hickey, C. (2002). Nitrate guideline values in ANZECC 2000. Memorandum MFE02237 prepared for Ministry for the Environment (New Zealand). NIWA Client Report: HAM2002-126.

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Paddock scale water quality monitoring of grazing management ...
Paddock scale water quality monitoring of grazing management ...
Direct Evidence Journal

Paddock scale water quality monitoring of grazing management ...

Context

  • Region Australia
  • Biome Tropical & Subtropical Maritime Islands
  • Land Use Livestock Grazing & Pasture
  • Assessment Not Stated
  • Evidence Type TargetCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 2 Jun 2026

Notes

Lower Boundary: Not applicable; the natural state is oligotrophic (near-zero nitrate), which is considered healthy. Upper Boundary: The detrimental threshold is defined by the onset of eutrophication, which occurs at concentrations well below official toxicity guidelines (e.g., ~7.2 mg/L for 95% species protection). Optimal Range: A state that minimizes departure from the natural baseline, with very low ambient concentrations and minimal elevation during runoff events. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.