Water Turbidity

AUS-ASC-FOR-WTU General Moderate confidence

Benchmark Value

36 NTU

Thresholds: Lower: —, Upper: 36

Direction: Lower is desirable ↓

Form: UpperThreshold

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 more severe detrimental threshold occurs at 36 NTU.

Metric Definition:

Nephelometric turbidity

Benchmark Definition:

This benchmark defines a severe detrimental threshold for water turbidity in the Alpine and Subalpine Complex under production forestry, indicating levels too murky for most aquatic organisms.

Justification:

Values over 36 NTU are categorized as too murky for most aquatic organisms to navigate and can lead to damage in gill structures.

Sources (1)

Preview of Assessing Water Quality - Secondary Education Years 9 to 12 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025,

Assessing Water Quality - Secondary Education Years 9 to 12 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025, Journal

Assessing water quality - ACT Waterwatch.

View Source

Supporting Sources (23)

Additional references from the underlying research that informed this benchmark.

1.1.5.2 Surface water quality - Bioregional Assessments |, accessed August 5, 2025,

Direct Evidence Government

The Turbidity Effect on Aquatic Life - Number Analytics, accessed July 12, 2025

View Source

Preview of An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria - MDPI, accessed August 1, 2025,

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria - MDPI, accessed August 1, 2025,

Direct Evidence Journal

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

View Source

Catchment Health Indicator Program Report (CHIP) 2022 - Upper ..., accessed July 16, 2025,

Contextual Support Journal

ACT Waterwatch. (2023). Catchment Health Indicator Program Report 2023.

View Source

Catchment Health Indicator Program Report 2021 - Upper Murrumbidgee Waterwatch, accessed August 12, 2025,

Contextual Support Journal

ANZECC/ARMCANZ (2000) Guidelines

View Source

Default guideline values - Water Quality Australia, accessed August 12, 2025

Contextual Support Government

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

View Source

Desktop review – Impact of bushfires on water quality, accessed August 10, 2025,

Contextual Support Journal

Australia's Sustainable Forest Management Framework of Criteria and Indicators 2008 - DAFF

View Source

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

Direct Evidence 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

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

Contextual Support GreyLiterature

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

View Source

Feral horses increase suspended sediment in subalpine streams

Contextual Support Journal

Feral horses increase suspended sediment in subalpine streams

View Source

In-Situ Support. (2024). What are typical turbidity values in natural environments?

Methodology Source GreyLiterature

Hanna Instruments Australia. (2024). The Complete Guide to Measuring Turbidity in Water.

View Source

Logging Impacts On Streams - Cloudfront.net

Direct Evidence Journal

The effects of forest management on water quality - SLU

View Source

NHMRC. (2011). Australian Drinking Water Guidelines - Part 5 Physical and Chemical Characteristics: Turbidity.

Contextual Support GreyLiterature

Ketos. (2024). Acceptable Turbidity Levels in Industrial Water.

View Source

North Esk Water Quality Study - Part 1

Direct Evidence Journal

North Esk Water Quality Study - Part 1.

View Source

NSW Water Quality Index Targets

Direct Evidence Journal

NSW Department of Climate Change, Energy, the Environment and Water. (2025). Targets to develop a water quality index for NSW rivers - River condition index.

View Source

Protecting waterways - Forestry Corporation, accessed July 12, 2025,

Direct Evidence Government

Forest Town Nature Conservation Group. (2024). Spa Ponds Water Quality.

View Source

Turbidity | Australian Drinking Water Guidelines - NHMRC, accessed August 11, 2025,

Regulatory Framework Government

Turbidity | Australian Drinking Water Guidelines - NHMRC, accessed August 3, 2025

View Source

Turbidity layer thresholds - WikiWatershed

Direct Evidence Journal

WikiWatershed. (2021). Layering Thresholds for Turbidity.

View Source

U.S. EPA. (2022). Turbidity Benchmark Monitoring for Dewatering under the Construction General Permit.

Contextual Support Journal

Tasmania Department of Primary Industries, Water and Environment. (2003). North Esk Water Quality Study - Part 1.

View Source

Preview of Upper Murrumbidgee Waterwatch Catchment Health Indicator Program (CHIP) Reports (e.g., 2021, 2023) and associated methodology defining "Excellent" water quality thresholds.

Upper Murrumbidgee Waterwatch Catchment Health Indicator Program (CHIP) Reports (e.g., 2021, 2023) and associated methodology defining "Excellent" water quality thresholds.

Contextual Support Journal

Catchment Health Indicator Program - Upper Murrumbidgee Waterwatch

View Source

Victoria Environment Protection Authority. (2018). State Environment Protection Policy (Waters).

Regulatory Framework Government

Victoria Environment Protection Authority. (2018). State Environment Protection Policy (Waters).

View Source

Victoria Government. (2021). Environment Reference Standard.

Contextual Support Journal

Victoria Government. (2021). Environment Reference Standard.

View Source

Water Quality Objectives - Border Rivers - NSW Government

Direct Evidence Government

Water Quality Objectives - Border Rivers - NSW Government

View Source

Webb, A. A., & Turner, L. (2004). Impact of mitigated forestry activities on turbidity: assessing the effect of improved harvesting practices.

Direct Evidence Journal

Webb, A. A., & Turner, L. (2004). Impact of mitigated forestry activities on turbidity: assessing the effect of improved harvesting practices.

View Source

Context

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

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

High risk of environmental impairment at this turbidity level. Note: stratification key mentions 'saline' which is semantically incorrect for turbidity. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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