Water Nitrate

AUS-TMS-IND-WNI General Moderate confidence

Benchmark Value

0.035 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

The most scientifically defensible proxy for the "best available condition" is the set of Water Quality Objectives (WQOs) developed for the Darwin Harbour Region... The WQO for NOx in the freshwater rivers and streams of the Darwin Harbour region, set at < 0.008 mg/L as N (< 0.035 mg/L as NO3−), is the most appropriate benchmark.

Metric Definition:

Water nitrate concentration expressed as mg/L nitrate (NO3−)

Benchmark Definition:

This benchmark represents the Water Quality Objective for nitrate in freshwater rivers and streams in the Darwin Harbour region, serving as a proxy for best available condition under industrial land use in tropical monsoonal savannas.

Justification:

This benchmark is justified as it is a locally-derived, ecologically-protective target based on high-quality reference sites and regulatory frameworks designed to protect aquatic ecosystems in the specified biome.

Sources (1)

Water Quality Objectives for the Darwin Harbour Region - Background Document - Department of Lands, Planning and Environment, accessed July 16, 2025, Journal

Water Quality Objectives for the Darwin Harbour Region - Background Document - Department of Lands, Planning and Environment

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Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

Australian Drinking Water Guidelines (ADWG)

Contextual Support

Australian Drinking Water Guidelines (ADWG)

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Nitrate in freshwater, toxicant default guideline values for protecting ..., accessed August 8, 2025

Direct Evidence Government

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

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Turbidity in Surface Water 14 Rehabilitation Standard for the Ranger uranium mine - DCCEEW, accessed August 1, 2025,

Methodology Source Government

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

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Water Quality Objectives for the Darwin Harbour Region

Direct Evidence

Water Quality Objectives for the Darwin Harbour Region

View Source

www.rrrc.org.au, accessed May 15, 2025,

Contextual Support Journal

Sediments and nutrients in north Queensland tropical streams: changes with agricultural development and pristine condition status (Technical Report No. 62, Australian Rainforest CRC, 2006)

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Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Industrial & Infrastructure Use
Assessment Not Stated
Evidence Type TargetCondition

Lifecycle

Status Active
Version 1
Effective From 2 Jun 2026

Notes

The benchmark is a proxy for best available condition in an industrial context where direct measurements are unavailable. The natural baseline is extremely low nitrate concentration, and the upper detrimental threshold for toxicity is much higher (~1.6 mg/L NO3−). The benchmark is stringent and protective, reflecting the 80th percentile of high-quality reference sites. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-TMS-IND-WNI family.