Water Turbidity

AUS-ASC-AGR-WTU General Moderate confidence

Benchmark Value

2 NTU
Range: 0 to 5 NTU
Thresholds: Lower: —, Upper: 5
Optimal Range: 0 to 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

A target of ≤ 2 NTU is proposed for achieving high environmental health.

Metric Definition:

Water turbidity measured in Nephelometric Turbidity Units (NTU) representing the cloudiness or haziness of water caused by suspended particulate matter in agricultural crop production within Australian Alpine and Subalpine Complex biome.

Benchmark Definition:

This benchmark represents the target water turbidity level for best-practice sustainable or regenerative agricultural crop production in the Australian Alpine and Subalpine Complex biome, aiming to maintain high environmental health by minimizing sediment and particulate matter in water.

Justification:

The reference value is based on the principle that best-practice regenerative agriculture in sensitive alpine/subalpine catchments should result in minimal sediment export, approaching the very low turbidity levels observed in minimally disturbed reference streams within this biome. The ANZECC 2000 guidelines suggest a 2-25 NTU range for upland rivers in slightly-moderately disturbed systems, with low turbidity typical of good condition. A target of ≤ 2 NTU represents high ecological health. Values consistently remaining < 5 NTU are considered indicative of good condition under best practice, as impacts on sensitive biota may occur above 5 NTU.

Sources (1)

Preview of ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia, accessed August 12, 2025
ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia, accessed August 12, 2025 Government

ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia

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Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000), accessed May 11, 2025,
Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000), accessed May 11, 2025,
Direct Evidence Journal

Northern Territory Government (2020) Darwin Harbour Region Water Quality Objectives, Report Card Section 3.0.

View Source
Preview of Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management - PubMed Central, accessed July 16, 2025,
Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management - PubMed Central, accessed July 16, 2025,
Direct Evidence Journal

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management. Water, 15(8), 1589.

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Context

  • Region Australia
  • Biome Alpine and Subalpine Complex
  • Land Use Agricultural Crop Production
  • Assessment Target Condition
  • Evidence Type TargetCondition

Lifecycle

  • Status Active
  • Version 1
  • Effective From 17 Mar 2026

Notes

Lower Critical Threshold: Not applicable for inorganic turbidity; lower is generally better, aiming for natural background levels. Optimal Range: < 2 NTU, extending to < 5 NTU under well-managed conditions. Upper Detrimental Threshold: Measurable ecological stress for sensitive species may begin > 5 NTU. Values > 25 NTU indicate significant degradation and poor land management.