Water Turbidity

AUS-TSW-FOR-WTU General Moderate confidence

Benchmark Value

25 NTU

Thresholds: Lower: 10, Upper: —

Direction: Lower is desirable ↓

Form: MinimumOnly

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 MinimumOnly Guard MaximumOnly Guard Point Guard OptimalRange Guard MaximumOnly Guard MaximumOnly Guard UpperThreshold Guard

Evidence & Context

The upper detrimental threshold is defined as a sustained mean turbidity > 25 NTU.

Metric Definition:

Sustained mean water turbidity in NTU indicating the threshold beyond which ecological degradation is likely.

Benchmark Definition:

This benchmark indicates the turbidity threshold beyond which ecological degradation is likely in temperate semi-arid woodland catchments under production forestry.

Justification:

Informed by national guidelines and empirical event data showing that sustained turbidity above 25 NTU signals chronic erosion problems and degraded state.

Sources (1)

(PDF) Impact of mitigated forestry activities on turbidity: assessing ..., accessed July 12, 2025,

(PDF) Impact of mitigated forestry activities on turbidity: assessing ..., accessed July 12, 2025,

View Source

Supporting Sources (20)

Additional references from the underlying research that informed this benchmark.

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

Contextual Support Government

1.1.5.2 Surface water quality - Bioregional Assessments |, accessed July 12, 2025,

View Source

Australia's forests – overview - DAFF, accessed August 5, 2025,

Contextual Support

Boland, D. J., & Dunn, A. T. (1985). Eucalyptus delegatensis: Its ecology and management. Forestry Commission of NSW.

View Source

Australia's State of the Forests Report, accessed August 12, 2025

Contextual Support Journal

Criteria and Indicators for Sustainable Forest Management in Victoria, accessed March 28, 2026,

View Source

Australia's Sustainable Forest Management - DAFF, accessed July 12, 2025,

Contextual Support

Sustainable forest management: the Australian context - DAFF, accessed July 12, 2025,

View Source

Best Management Practices - National Association of State Foresters, accessed July 12, 2025,

Contextual Support Regulatory Framework Government

Best Management Practices - National Association of State Foresters, accessed August 10, 2025

View Source

Deriving guideline values using reference-site data - Water Quality Australia, accessed August 12, 2025

Contextual Support Government

Water Quality Guidelines Home - Water Quality Australia

View Source

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

How Sustainable Forestry Works - Science | HowStuffWorks, accessed July 12, 2025,

Contextual Support GreyLiterature

How Sustainable Forestry Works - Science | HowStuffWorks, accessed July 12, 2025,

View Source

Logging Impacts On Streams - Cloudfront.net

Contextual Support Journal

The effects of forest management on water quality - SLU, accessed August 10, 2025

View Source

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

Contextual Support Direct Evidence

Australian and New Zealand Guidelines for Fresh and Marine Water ...

View Source

NVIS Fact sheet MVG 13 – Acacia open woodlands - DCCEEW, accessed July 13, 2025,

Contextual Support Journal

NVIS Fact sheet MVG 13 Acacia open woodlands - DCCEEW, accessed July 10, 2025,

View Source

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

Contextual Support Government

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

View Source

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

Contextual Support GreyLiterature

The Turbidity Effect on Aquatic Life - Number Analytics, accessed July 31, 2025,

View Source

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

Contextual Support Government

Australian Drinking Water Guidelines

View Source

Turbidity | River Detectives, accessed July 16, 2025,

Contextual Support Journal

Turbidity | River Detectives, accessed July 27, 2025,

View Source

Turbidity and Water | U.S. Geological Survey - USGS.gov, accessed August 12, 2025,

Contextual Support

Turbidity and Water | U.S. Geological Survey - USGS.gov, accessed July 31, 2025,

View Source

Turbidity, accessed August 3, 2025,

Contextual Support Journal

Turbidity, accessed July 31, 2025,

View Source

Water Quality and Forestry Best Management Practices, accessed July 12, 2025,

Contextual Support Government

Water Quality and Forestry Best Management Practices, accessed July 12, 2025,

View Source

Why Measure Turbidity? - Montclair State University, accessed August 12, 2025,

Contextual Support GreyLiterature

Feral horses (Equus caballus) increase suspended sediment in subalpine streams, accessed August 3, 2025

View Source

Woodlands of Australia - A biography of the Australian continent, accessed July 12, 2025,

Contextual Support GreyLiterature

Semi-arid woodlands (shrubby sub-formation) | NSW Environment, Energy and Science, accessed July 8, 2025, )

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Production Forestry
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 15 Mar 2026

Notes

Short-term spikes above this level may occur but persistent exceedance indicates management failure. ConsistencyResolver applied 2026-03-23 00:14 UTC: UpperThreshold 25 → 10 (check: MinAboveMax, rationale: Swapping the MinimumOnly benchmark's UpperThreshold from 25 to 10 aligns with the lower threshold and will auto-correct the form to MaximumOnly, resolving the contradiction.) ConsistencyResolver applied 2026-03-24 20:12 UTC: LowerThreshold → 10 (check: MinEqualsMax, rationale: The Notes state that short-term spikes above 10 NTU may occur but persistent exceedance indicates failure, so 10 NTU is a lower threshold indicating degradation below which values are healthy. Moving the 10 from UpperThreshold to LowerThreshold aligns with this and will auto-correct the form to MinimumOnly.) ConsistencyResolver applied 2026-03-24 20:12 UTC: UpperThreshold 10 → (check: MinEqualsMax, rationale: Clearing the UpperThreshold field to avoid conflict with the new LowerThreshold and to maintain proper threshold direction.)

Related Benchmarks

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