Water Turbidity

AUS-ASC-FOR-WTU General Moderate confidence

Benchmark Value

10 NTU
Thresholds: Lower: —, Upper: 10
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 MinimumOnly Guard MaximumOnly Guard Point Guard OptimalRange Guard MaximumOnly Guard MaximumOnly Guard UpperThreshold Guard

Evidence & Context

The initial upper boundary trigger where ecological harm begins is 10 NTU.

Metric Definition:

Nephelometric turbidity

Benchmark Definition:

This benchmark marks the turbidity level at which ecological harm to aquatic life begins due to impaired photosynthesis and navigation.

Justification:

Long-term turbidity exceeding 10 NTU is detrimental to aquatic life because it prevents efficient photosynthesis by reducing the clear path for light.

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 (5)

Additional references from the underlying research that informed this benchmark.

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
Preview of Feral horses (Equus caballus) increase suspended sediment in subalpine streams
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
Preview of North Esk Water Quality Study - Part 1
North Esk Water Quality Study - Part 1
Direct Evidence Journal

North Esk Water Quality Study - Part 1

View Source
Preview of Turbidity | Australian Drinking Water Guidelines - NHMRC, accessed August 11, 2025,
Turbidity | Australian Drinking Water Guidelines - NHMRC, accessed August 11, 2025,
Regulatory Framework Government

Australian Drinking Water Guidelines

View Source
Preview of Water Quality Objectives - Border Rivers - NSW Government
Water Quality Objectives - Border Rivers - NSW Government
Direct Evidence Government

Bioregional Assessment: Gippsland Basin - Surface Water Quality

View Source

Context

  • Region Australia
  • Biome Alpine and Subalpine Complex
  • Land Use Production Forestry
  • Assessment Pristine Reference
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 9 Apr 2026

Notes

ACT Waterwatch guidelines explicitly state: 'Good environmental water clarity should be below 10 NTU'.

Related Benchmarks

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

100 NTU Moderate
Production Forestry · Pristine Reference · Summer
UpperThreshold Active v1