Water Nitrate

AUS-TSR-IND-WNI General Moderate confidence

Benchmark Value

4.87 mg/L
Direction: Lower is desirable ↓
Form: MaximumOnly

Scoring Curve

This curve shows how a field measurement for this indicator would score across all available benchmark forms in this context. The scoring engine uses 11 benchmarks together — the OptimalRange form drives the primary score, while 10 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary LowerThreshold Guard MaximumOnly Guard MaximumOnly Guard Point Guard MinimumOnly Guard Point Guard OptimalRange Guard MaximumOnly Guard MaximumOnly Guard Point Guard

Evidence & Context

Upper Detrimental Threshold (95% Species Protection): 1.1 mg/L as NO3−​-N.1 Converted to mg/L as NO3−​: 1.1 mg/L N×4.4268=4.87 mg/L NO3−​.This value represents the concentration above which direct toxic effects on a significant portion (5%) of aquatic species are expected.

Metric Definition:

Upper detrimental threshold for nitrate concentration causing direct toxic effects to aquatic species

Benchmark Definition:

This benchmark represents the nitrate concentration in tropical rainforest catchments above which direct toxic effects are expected for a significant portion of aquatic species.

Justification:

This threshold is based on the draft 2024 Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG) 95% species protection guideline for soft water, representing a scientifically authoritative toxicant guideline.

Sources (1)

Preview of Toxicant default guideline values for aquatic ecosystem protection ..., accessed August 8, 2025
Toxicant default guideline values for aquatic ecosystem protection ..., accessed August 8, 2025 Journal

Nitrate in freshwater, toxicant default guideline values for protecting aquatic ecosystems

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of Nitrate and nitrite | Australian Drinking Water Guidelines - NHMRC, accessed August 8, 2025
Nitrate and nitrite | Australian Drinking Water Guidelines - NHMRC, accessed August 8, 2025
Contextual Support Government

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG 2018)

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Industrial & Infrastructure Use
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

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

Notes

This value represents the concentration above which direct toxic effects on a significant portion (5%) of aquatic species are expected in tropical rainforest catchments. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.