Water Nitrate

AUS-AMR-AQU-WNI General Moderate confidence

Benchmark Value

11.5 mg/L

Thresholds: Lower: —, Upper: 11.5

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.

Evidence & Context

For moderately hard water (30–150 mg/LCaCO3), a common condition in many surface waters, the upper limit for 95% species protection is 11.5 mg/L NO3−.

Metric Definition:

Upper detrimental threshold for nitrate concentration in receiving waters, defined by ANZG toxicity guidelines for moderately hard water (30–150 mg/L CaCO3).

Benchmark Definition:

This benchmark represents the nitrate concentration above which direct toxic harm to aquatic life occurs, indicating severe ecological degradation in the Arid Mountain Ranges & Uplands biome.

Justification:

This threshold is based on the ANZG Default Guideline Values derived from laboratory toxicity testing and adjusted for water hardness relevant to the biome.

Sources (1)

(PDF) Water quality parameters and population characteristics for the Flinders Ranges Gudgeon - ResearchGate

Toxicant default guideline values for aquatic ecosystem protection ...

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Establishment of reference conditions and trigger values for chemical, physical and micro-biological indicators in New Zealand streams and rivers - Ministry for the Environment, accessed August 11, 2025,

Establishment of reference conditions and trigger values for chemical, physical and micro-biological indicators in New Zealand streams and rivers - Ministry for the Environment, accessed August 11, 2025,

Direct Evidence Journal

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000)

View Source

SA Arid Lands Landscape Regional Summary 2022 Aquatic ..., accessed July 30, 2025,

Direct Evidence Government

(PDF) Effects of increasing salinity on freshwater ecosystems in ..., accessed July 31, 2025,

View Source

Context

Region Australia
Biome Arid Mountain Ranges & Uplands
Land Use Aquaculture
Assessment Degradation Threshold
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 19 Mar 2026

Notes

Exceeding this level indicates unsustainable aquaculture operations causing environmental damage.

Related Benchmarks

Other benchmarks in the AUS-AMR-AQU-WNI family.