Water Turbidity

AUS-ASC-AGR-WTU General Moderate confidence

Benchmark Value

5 NTU

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

An early warning threshold for ecological stress is identified at > 5 NTU.

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 an early warning maximum turbidity threshold of 5 NTU, above which measurable ecological stress may begin in alpine and subalpine agricultural catchments.

Justification:

Scientific literature indicates that negative ecological impacts on sensitive aquatic organisms can begin to occur at turbidity levels exceeding 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

View Source

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

ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia

View Source

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, Journal

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

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

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

NSW alpine resorts environmental performance report 2020–21

Direct Evidence Journal

NSW Alpine Resorts Environmental Performance Report 2020–21

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 DegradationThreshold

Lifecycle

Status Superseded
Version 2
Effective From 3 Jun 2026
Effective To 3 Jun 2026

Notes

Exceeding 5 NTU, particularly if persistent, suggests the onset of measurable ecological stress for sensitive species and processes within alpine and subalpine streams. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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