Water Turbidity

AUS-ASC-AQU-WTU General Moderate confidence

Benchmark Value

25 NTU

Direction: Lower is desirable ↓

Form: Point

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 15 benchmarks together — the OptimalRange form drives the primary score, while 14 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard OptimalRange Guard Point Guard MaximumOnly Guard MaximumOnly Guard MaximumOnly Guard MaximumOnly Guard OptimalRange Guard MaximumOnly Guard Point Guard LowerThreshold Guard OptimalRange Guard MaximumOnly Guard MaximumOnly Guard

Evidence & Context

The upper boundary is established at 25 NTU. Turbidity levels exceeding this value are indicative of a degraded state with significant negative ecological consequences.

Metric Definition:

Upper turbidity threshold in NTU beyond which sublethal negative effects on salmonid health and behavior occur.

Benchmark Definition:

This benchmark indicates the turbidity threshold beyond which ecological degradation occurs for salmonid aquaculture in alpine environments.

Justification:

Based on documented sublethal effects such as reduced growth and avoidance behavior, and consistent with ANZECC guidelines.

Sources (2)

Effects of Turbidity and Suspended Solids on Salmonids - ResearchGate GreyLiterature

Effects of Turbidity and Suspended Solids on Salmonids - ResearchGate

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Preview of Water Quality Objectives - Border Rivers - NSW Government, accessed August 12, 2025

Water Quality Objectives - Border Rivers - NSW Government, accessed August 12, 2025 Government

(PDF) Impact of mitigated forestry activities on turbidity: assessing ...

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Supporting Sources (38)

Additional references from the underlying research that informed this benchmark.

(PDF) Climate change impacts on Australia's alpine ecosystems - ResearchGate, accessed on May 28, 2025,

Contextual Support GreyLiterature

(PDF) Climate change impacts on Australia's alpine ecosystems - ResearchGate, accessed August 5, 2025

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Alpine Trout Farm

Irrelevant

Alpine Trout Farm

View Source

Aquaculture in NSW facts & figures 2024

Contextual Support Journal

Aquaculture in NSW facts & figures 2024, accessed August 10, 2025,

View Source

Australia: aquaculture exceeded the value of wild catch by 2021-22

Contextual Support GreyLiterature

Australia: aquaculture exceeded the value of wild catch by 2021-22

View Source

Australia's Aquaculture industry - DAFF, accessed August 17, 2025,

Contextual Support Government

Australian fisheries and aquaculture outlook 2024 - DAFF

View Source

Australian and New Zealand guidelines for fresh and marine water quality, accessed July 19, 2025,

Regulatory Framework Government

Australian Alps Liaison Committee (AALC). (2011). Caring for our Australian Alps catchments: A climate change action strategy. Department of Climate Change and Energy Efficiency.

View Source

$Preview of C:\My Documents\BiOps and Notes\Milltown Dam\MTD Opinion\Appendix A.wpd - US EPA$

C:\My Documents\BiOps and Notes\Milltown Dam\MTD Opinion\Appendix A.wpd - US EPA

Contextual Support Journal

C:\My Documents\BiOps and Notes\Milltown Dam\MTD Opinion\Appendix A.wpd - US EPA

View Source

Caring for our Australian Alps Catchments, accessed August 28, 2025,

Contextual Support Journal

Patterns of variation in Australian alpine soils and their relationships to parent material, vegetation formation, climate and t, accessed May 27, 2025

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Dissolved Oxygen (DO) Turbidity - Interstate Commission on the Potomac River Basin, accessed July 12, 2025,

Contextual Support Journal

Dissolved Oxygen (DO) Turbidity - Interstate Commission on the Potomac River Basin

View Source

Does turbidity determine fish growth? - American Fisheries Society

Contextual Support GreyLiterature

Does turbidity determine fish growth? - American Fisheries Society

View Source

From Hatch to Catch - Buxton Trout & Salmon Farm's commitment to Sustainability since 1958.

Contextual Support GreyLiterature

From Hatch to Catch - Buxton Trout & Salmon Farm's commitment to Sustainability since 1958.

View Source

Gaden Trout Hatchery - Away We Go Tours | School Excursions & Group Tours

Irrelevant

Gaden Trout Hatchery - Away We Go Tours | School Excursions & Group Tours

View Source

Gaden Trout Hatchery - Snowy Mountains Fishing

Irrelevant

Gaden Trout Hatchery - Snowy Mountains Fishing

View Source

Gaden Trout Hatchery - Thredbo River - Visit Cooma, accessed August 17, 2025,

Contextual Support Government

Gaden Trout Hatchery - Thredbo River - Visit Cooma

View Source

Gaden Trout Hatchery EPA Pollution Monitoring Data - August 2021

Direct Evidence Journal

Gaden Trout Hatchery EPA Pollution Monitoring Data - August 2021

View Source

Impacts of Sediment to Aquatic Habitats

Contextual Support Journal

Impacts of Sediment to Aquatic Habitats

View Source

Improved Methods for Correlating Turbidity and Suspended Solids for Monitoring - CLU-IN

Methodology Source Journal

Water-quality and ecosystem impacts of recreation in streams: Monitoring and management, accessed July 19, 2025,

View Source

Preview of Improvement of the Water Quality in Rainbow Trout Farming by Means of the Feeding Type and Management over 10 Years (2009–2019), accessed August 10, 2025

Improvement of the Water Quality in Rainbow Trout Farming by Means of the Feeding Type and Management over 10 Years (2009–2019), accessed August 10, 2025

Contextual Support Journal

Improvement of the Water Quality in Rainbow Trout Farming by Means of the Feeding Type and Management over 10 Years (2009–2019) - PMC

View Source

Lethal Turbidity Levels for Common Fish and Invertebrates in Auckland Streams - CiteSeerX

Contextual Support

Lethal Turbidity Levels for Common Fish and Invertebrates in Auckland Streams - CiteSeerX

View Source

Managing Recreational Trout Fisheries - VFA

Contextual Support Government

Managing Recreational Trout Fisheries - VFA

View Source

National Guidelines for Water Quality - Department of Natural Resources and Environment Tasmania, accessed August 1, 2025,

Contextual Support

Using the ANZECC Guidelines and Water Quality Objectives in NSW

View Source

Remote Sensing Retrieval of Turbidity in Alpine Rivers based on high Spatial Resolution Satellites - MDPI

Methodology Source Journal

Remote Sensing Retrieval of Turbidity in Alpine Rivers based on high Spatial Resolution Satellites - MDPI

View Source

Review of water quality studies in the Australian Alps, accessed August 12, 2025,

Contextual Support Government

Feral horses (Equus caballus) increase suspended sediment in subalpine streams

View Source

Snapshot of Australia's commercial fisheries and aquaculture - DAFF, accessed August 17, 2025,

Contextual Support Government

Snapshot of Australia's commercial fisheries and aquaculture - DAFF

View Source

Snowy 2.0 Recreational Fishing Management Plan

Contextual Support Journal

Snowy 2.0 Recreational Fishing Management Plan

View Source

Snowy Mountains Trout | freshtrout.com.au | Snowy Mountains Trout NSW

Contextual Support GreyLiterature

About | Snowy Mountains Trout | freshtrout.com.au

View Source

Stony Creek Fish Farm

Contextual Support GreyLiterature

Stony Creek Fish Farm

View Source

The conversion of Nephelometric Turbidity Units (NTU) into mg/l for Alberta Transportations turbidity specification is required

Methodology Source Journal

The conversion of Nephelometric Turbidity Units (NTU) into mg/l for Alberta Transportations turbidity specification is required

View Source

trout culture in recirculatory aquaculture system (ras) - National Fisheries Development Board

Contextual Support

trout culture in recirculatory aquaculture system (ras) - National Fisheries Development Board

View Source

Turbidity in freshwater habitats of Alaska - A review of published and unpublished literature relevant t

Contextual Support Journal

Turbidity in freshwater habitats of Alaska - A review of published and unpublished literature relevant t

View Source

Using the ANZECC Guidelines and Water Quality Objectives in NSW, accessed August 11, 2025,

Contextual Support Journal

Reference-site data - Water Quality Australia

View Source

Water monitoring - NSW Department of Primary Industries, accessed August 17, 2025,

Contextual Support Government

Water monitoring - NSW Department of Primary Industries

View Source

Water Quality | Snowy Hydro

Contextual Support Journal

Water Quality | Snowy Hydro

View Source

Water quality data and reports - EPA Victoria, accessed August 12, 2025,

Contextual Support Government

Water quality data and reports - EPA Victoria

View Source

Water quality guidelines - Queensland Environment Department, accessed August 1, 2025,

Contextual Support Government

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000)

View Source

Water Quality Standards - Turbidity Technical Review - Oregon.gov, accessed August 11, 2025,

Contextual Support Journal

Positive responses of benthic macroinvertebrates to spatial and temporal reductions in water pollution downstream from a trout farm outlet | Knowledge and Management of Aquatic Ecosystems, accessed August 17, 2025

View Source

What is NTU? - TecnoConverting Engineering

Contextual Support GreyLiterature

What is NTU? - TecnoConverting Engineering

View Source

www.environment.nsw.gov.au, accessed on May 25, 2025,

Contextual Support

The Australian Alps Bioregion - Environment and Heritage, accessed on May 27, 2025,

View Source

Context

Region Australia
Biome Alpine and Subalpine Complex
Land Use Aquaculture
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

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

Notes

Exceeding 25 NTU signals a transition from healthy to degraded environmental state. AssessmentContext defaulted to 'Not Stated' because the source document did not state one. Pipeline correction 2026-06-03c: Rejected — erroneous BenchmarkForm (Point+UpperGuard for degradation threshold; correct form MaximumOnly+UpperGuard). MaximumOnly slot occupied by ID 1347 (5 NTU). Requires StratificationKey (e.g., '25-NTU-degradation-trigger') to coexist. Requeue document with prompt v3.7.

Related Benchmarks

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