Water Nitrate

AUS-TMS-CON-WNI General Moderate confidence

Benchmark Value

0.64 mg/L as NO3‑N

Thresholds: Lower: —, Upper: 0.64

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 8 benchmarks together — the OptimalRange form drives the primary score, while 7 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

The Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZG) provide Default Guideline Values (DGVs) for nitrate based on direct toxicity to aquatic organisms. For soft waters (which are common in nutrient-poor savanna catchments with low dissolved solids), the 99% species protection level DGV (intended for high conservation value systems) is 0.64 mg/L NO3‑N.

Metric Definition:

Water nitrate concentration expressed as milligrams per liter as Nitrate-Nitrogen (NO3‑N).

Benchmark Definition:

This benchmark represents the default guideline value for nitrate based on chronic toxicity to aquatic organisms in soft waters of savanna catchments.

Justification:

Represents a threshold for direct toxic effects on sensitive species, indicating significant degradation.

Supporting Sources (52)

Additional references from the underlying research that informed this benchmark.

Preview of (PDF) Discharge-driven seasonal pattern of ionic solutes, suspended sediment and water clarity for a tropical savanna river in northern Australia - ResearchGate, accessed May 14, 2025,

(PDF) Discharge-driven seasonal pattern of ionic solutes, suspended sediment and water clarity for a tropical savanna river in northern Australia - ResearchGate, accessed May 14, 2025,

Contextual Support Journal

Environmental Water Requirements of Vallisneria nana in the Daly River, Northern Territory1 | Request PDF - ResearchGate

View Source

Deriving guideline values using reference-site data - Water Quality Australia, accessed August 12, 2025

Direct Evidence Government

Water Quality Guidelines Home - Water Quality Australia

View Source

Preview of Diatom–water quality thresholds in South Australian streams indicate a need for more stringent water quality guidelines | Request PDF - ResearchGate, accessed May 11, 2025,

Diatom–water quality thresholds in South Australian streams indicate a need for more stringent water quality guidelines | Request PDF - ResearchGate, accessed May 11, 2025,

Direct Evidence

Validating species sensitivity distributions using salinity tolerance of riverine macroinvertebrates in the southern Murray–Darling Basin (Victoria, Australia) - Canadian Science Publishing

View Source

Litchfield Savanna BASE Contextual, Soil Physico-Chemical Data ..., accessed May 20, 2025,

Contextual Support GreyLiterature

Litchfield Savanna BASE Contextual, Soil Physico-Chemical Data ..., accessed May 20, 2025,

View Source

Preview of Simultaneous exposure to nitrate and low pH reduces the blood oxygen-carrying capacity and functional performance of a freshwater fish | Conservation Physiology | Oxford Academic, accessed May 20, 2025,

Simultaneous exposure to nitrate and low pH reduces the blood oxygen-carrying capacity and functional performance of a freshwater fish | Conservation Physiology | Oxford Academic, accessed May 20, 2025,

Contextual Support Journal

View Source

Surface water chemistry monitoring protocol to assess ... - DCCEEW, accessed May 20, 2025,

Contextual Support Methodology Source

Surface water chemistry monitoring protocol to assess ... - DCCEEW, accessed May 20, 2025,

View Source

Toxicant default guideline values for aquatic ecosystem protection ...

Direct Evidence

Toxicant default guideline values for aquatic ecosystem protection ...

Toxicant default guideline values for aquatic ecosystem protection ...

Direct Evidence

Toxicant default guideline values for aquatic ecosystem protection ...

Toxicant default guideline values for aquatic ecosystem protection ...

Direct Evidence

Default guideline values - Water Quality Australia

View Source

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

Direct Evidence Journal

Toxicant default guideline values for aquatic ecosystem protection ...

View Source

tuvalu-data.sprep.org, accessed May 20, 2025,

Contextual Support