Water Nitrate — Benchmark Detail

Benchmark Value

10 mg/L

Direction: Lower is desirable ↓

Form: MinimumOnly

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 10 benchmarks together — the OptimalRange form drives the primary score, while 9 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Levels approaching 10–50 mg/L cause demonstrable sub-lethal harm (reduced growth, impaired performance) to sensitive native freshwater fauna like Silver Perch.

Metric Definition:

Nitrate concentration in water discharge above which sub-lethal harm to native freshwater fauna occurs

Benchmark Definition:

This benchmark defines the threshold nitrate concentration in water discharge above which sub-lethal harm to native freshwater fauna begins, indicating increasing ecological risk beyond best-practice conditions.

Justification:

Multiple studies and meta-analysis confirm sub-lethal harm effects at nitrate concentrations in the range of 10-50 mg/L.

Sources (1)

Preview of Aquaculture viability. A technical report to the Australian Government from the CSIRO Northern Australia Water Resource Assessme

Aquaculture viability. A technical report to the Australian Government from the CSIRO Northern Australia Water Resource Assessme Journal

Living in polluted waters: A meta-analysis of the effects of nitrate and ...

View Source

Supporting Sources (4)

Additional references from the underlying research that informed this benchmark.

Preview of Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 5, 2025,

Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 5, 2025,

Contextual Support GreyLiterature

(PDF) Identifying ecological barriers to restoration in temperate grassy woodlands: soil changes associated with different degradation states - ResearchGate, accessed August 4, 2025,

View Source

Preview of Living in polluted waters: A meta-analysis of the effects of nitrate and interactions with other environmental stressors on freshwater taxa - PubMed, accessed August 17, 2025,

Living in polluted waters: A meta-analysis of the effects of nitrate and interactions with other environmental stressors on freshwater taxa - PubMed, accessed August 17, 2025,

Direct Evidence Journal

Living in polluted waters: A meta-analysis of the effects of nitrate and ...

View Source

Toxicant default guideline values for aquatic ecosystem protection ...

Direct Evidence

Water Quality Objectives - Murray River catchment (NSW)

View Source

Water resource assessment for the Southern Gulf catchments - CSIRO

Direct Evidence Journal

(PDF) Identifying ecological barriers to restoration in temperate ...

View Source

Context

Region Australia
Biome Temperate Grassy Woodlands & Plains
Land Use Aquaculture
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 2 Jun 2026

Notes

There is a gradient of degradation above the 0.5 mg/L benchmark, with documented sub-lethal harm effects starting at levels approaching 10 mg/L and extending up to 50 mg/L and beyond. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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