Water Turbidity

AUS-ASC-IND-WTU General Moderate confidence

Benchmark Value

25 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.

Evidence & Context

Sustained turbidity levels exceeding 25 NTU are indicative of a degraded natural state, posing a significant risk to aquatic ecosystem health.

Metric Definition:

Water turbidity in NTU indicating the upper detrimental threshold beyond which ecological degradation occurs.

Benchmark Definition:

Upper detrimental threshold for turbidity indicating ecological harm in alpine streams.

Justification:

This threshold is supported by regulatory standards and ecological impact studies indicating risk of harm above this level.

Sources (1)

Preview of Snowy - NSW Government Water, accessed August 17, 2025,

Snowy - NSW Government Water, accessed August 17, 2025, Government

ANZECC 2000 guidelines for fresh and marine water quality

View Source

Supporting Sources (23)

Additional references from the underlying research that informed this benchmark.

An Assessment of Feral Horse Impacts on Treeless Drainage Lines in the Australian Alps - December 2015, accessed August 17, 2025,

Contextual Support Journal

An Assessment of Feral Horse Impacts on Treeless Drainage Lines in the Australian Alps - December 2015, accessed August 17, 2025,

View Source

bioone.org, accessed August 17, 2025, )023[0247:EIOTOT]2.0.CO;2.pdf

Contextual Support GreyLiterature

Feral horses (Equus caballus) increase suspended sediment in subalpine streams, accessed August 17, 2025

View Source

DRINKING WATER QUALITY ANNUAL REPORT 2022-2023, accessed August 17, 2025,

Contextual Support Journal

Full article: Evaluating the impact of low intensity farming on alpine river water quality: case study from south Westland, Aotearoa New Zealand

View Source

EAWAG news 54e: The Ecology of Alpine Streams, accessed August 17, 2025,

Contextual Support

EAWAG news 54e: The Ecology of Alpine Streams, accessed August 17, 2025,

View Source

Preview of Effects of Sedimentation and Turbidity on Lotic Food Webs: A Concise Review for Natural Resource Managers - Southern Research Station, accessed July 16, 2025,

Effects of Sedimentation and Turbidity on Lotic Food Webs: A Concise Review for Natural Resource Managers - Southern Research Station, accessed July 16, 2025,

Contextual Support Journal

Effects of Sedimentation and Turbidity on Lotic Food Webs: A Concise Review for Natural Resource Managers - Southern Research Station, accessed August 17, 2025

View Source

Preview of Effects of turbidity and introduced tilapia (Oreochromis spp) on macrophytes and invertebrates in a shallow tropical lake | Knowledge and Management of Aquatic Ecosystems, accessed July 24, 2025

Effects of turbidity and introduced tilapia (Oreochromis spp) on macrophytes and invertebrates in a shallow tropical lake | Knowledge and Management of Aquatic Ecosystems, accessed July 24, 2025

Contextual Support Journal

Waterhouse, J. (2010) Thresholds of major pollutants with regard to impacts on instream and marine ecosystems, accessed July 21, 2025

View Source

Environment - Perisher, accessed August 17, 2025,

Contextual Support Government

Environment - Perisher, accessed August 17, 2025,

View Source

Environment & Sustainability - Thredbo, accessed August 17, 2025,

Contextual Support GreyLiterature

Environment & Sustainability - Thredbo, accessed August 17, 2025,

View Source

Environmental Impacts of Tourism on the Australian Alps Protected Areas - ResearchGate, accessed August 17, 2025,

Contextual Support Journal

Environmental Impacts of Tourism on the Australian Alps Protected Areas - ResearchGate, accessed August 28, 2025,

View Source

Environmental Initiatives 2021 | Thredbo, accessed August 17, 2025,

Contextual Support Journal

Environmental Initiatives 2021 | Thredbo, accessed August 17, 2025,

View Source

Feral horses (Equus caballus) increase suspended sediment in subalpine streams, accessed August 12, 2025,

Direct Evidence Journal

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management

View Source

Kosciuszko National Park water quality monitoring, accessed August 12, 2025,

Contextual Support Government

theaustralianalpsnationalparks.org, accessed August 17, 2025

View Source

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

Direct Evidence

Using the ANZECC Guidelines and Water Quality Objectives in NSW

View Source

NSW Alpine Resorts Environmental Performance Report 2019–20, accessed August 17, 2025,

Contextual Support Journal

NSW alpine resorts environmental performance report 2020–21, accessed August 17, 2025,

View Source

NSW alpine resorts environmental performance report 2020–21

Direct Evidence Journal

NSW Alpine Resorts Environmental Performance Report 2020–21

View Source

Preview of Preliminary information for developing sediment guidelines for streams of the West Coast, New Zealand - Envirolink, accessed August 17, 2025,

Preliminary information for developing sediment guidelines for streams of the West Coast, New Zealand - Envirolink, accessed August 17, 2025,

Contextual Support Journal

Preliminary information for developing sediment guidelines for streams of the West Coast, New Zealand - Envirolink, accessed August 1, 2025,

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

Snowy Mountains Hydro | National Museum of Australia, accessed August 17, 2025,

Contextual Support GreyLiterature

Snowy Mountains Hydro | National Museum of Australia, accessed August 17, 2025,

View Source

The Snowy Mountains Hydro-electric Scheme:how did it manage without an EIA? - Open Research Repository, accessed August 17, 2025,

Contextual Support

The Snowy Mountains Hydro-electric Scheme:how did it manage without an EIA? - Open Research Repository, accessed August 17, 2025,

View Source

Thredbo village environment walk, accessed August 17, 2025,

Contextual Support Journal

Sustainability Report 2023 - Thredbo, accessed August 17, 2025

View Source

Turbidity and Water | U.S. Geological Survey - USGS.gov, accessed August 17, 2025,

Contextual Support

Turbidity and Water | U.S. Geological Survey - USGS.gov, accessed August 17, 2025,

View Source

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

Contextual Support Government

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

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

Context

Region Australia
Biome Alpine and Subalpine Complex
Land Use Industrial & Infrastructure Use
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 2
Effective From 1 Jun 2026

Notes

Values above 25 NTU signify a degraded state and pose significant risk to aquatic ecosystem health, exceeding the ANZECC (2000) trigger value for upland rivers. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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