Water Turbidity

AUS-ASC-AGR-WTU General Moderate confidence

Benchmark Value

2 NTU

Thresholds: Lower: —, Upper: 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. The scoring engine uses 9 benchmarks together — the OptimalRange form drives the primary score, while 8 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

A target of ²6le; 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.

Benchmark Definition:

This benchmark represents a target maximum water turbidity of 2 NTU to achieve high environmental health in alpine and subalpine agricultural catchments. Turbidity above 5 NTU indicates poorer conditions under best-practice management.

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 (often <1-2 NTU) 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 ²6le; 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 (3)

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria 21 Journal

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria 21

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

ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia

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NSW alpine resorts environmental performance report 2020–21 Journal

NSW Alpine Resorts Environmental Performance Report 2020–21

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

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.

View Source

Regenerative agriculture – Case studies from Western Australia, accessed May 13, 2025

Direct Evidence

Soil management guides - NSW Department of Primary Industries

View Source

Context

Region Australia
Biome Alpine and Subalpine Complex
Land Use Agricultural Crop Production
Assessment Not Stated
Evidence Type TargetCondition

Lifecycle

Status Superseded
Version 1
Effective From 3 Jun 2026
Effective To 3 Jun 2026

Notes

Upper Detrimental Threshold: 5 NTU. Values consistently below 5 NTU are considered indicative of good condition under best-practice management. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-ASC-AGR-WTU family.