Water Turbidity

AUS-ASC-CON-WTU General Moderate confidence

Benchmark Value

No specific value — see range

Range: 0 to 2 NTU

Optimal Range: 0 to 2

Direction: Lower is desirable ↓

Form: OptimalRange

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 11 benchmarks together — the OptimalRange form drives the primary score, while 10 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Based on an analysis of current, site-specific data from well-managed conservation areas within the Australian Alpine and Subalpine Complex, the reference value for water turbidity representing the best available natural condition is: < 2 NTU (Nephelometric Turbidity Units), and often < 1 NTU.

Metric Definition:

Water turbidity is an optical property of water that causes light to be scattered and absorbed rather than transmitted in straight lines. It is a measure of the cloudiness or haziness of water caused by suspended particulate matter, which can include clay, silt, fine inorganic and organic matter, algae, and other microscopic organisms.

Benchmark Definition:

This benchmark defines the optimal water turbidity range for pristine alpine and subalpine conservation areas in Australia, indicating very low suspended particulate matter and high water clarity.

Justification:

The benchmark is derived from multiple monitoring sites within Kosciuszko National Park, an Australian Alpine and Subalpine Complex under conservation management, demonstrating high environmental health ('good' condition ratings). These sites consistently report very low turbidity, often below 1 NTU.

Sources (1)

NSW alpine resorts environmental performance report 2020–21 Journal

NSW Alpine Resorts Environmental Performance Report 2020–21

View Source

Supporting Sources (5)

Additional references from the underlying research that informed this benchmark.

Kosciuszko National Park EcoHealth Scorecard 2022–23

Contextual Support GreyLiterature

Assessment of the Values of Kosciuszko National Park (Chapter 8)

View Source

Kosciuszko National Park's health a mixed diagnosis in first EcoHealth Scorecard

Contextual Support GreyLiterature

Kosciuszko National Park's health a mixed diagnosis in first EcoHealth Scorecard

View Source

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

Regulatory Framework

Using the ANZECC Guidelines and Water Quality Objectives in NSW

View Source

Turbidity | River Detectives, accessed July 16, 2025,

Contextual Support Journal

Kosciuszko National Park's health a mixed diagnosis in first EcoHealth Scorecard

View Source

Victorian Water Quality Analysis 2022 Technical Report - Water and ..., accessed August 12, 2025,

Contextual Support Journal

Victorian Water Quality Analysis 2022 Technical Report

View Source

Context

Region Australia
Biome Alpine and Subalpine Complex
Land Use Conservation / Protected Natural Areas
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Superseded
Version 1
Effective From 3 Jun 2026
Effective To 3 Jun 2026

Notes

The optimal turbidity is very low, typically < 2 NTU and frequently < 1 NTU, reflecting minimal anthropogenic disturbance and healthy ecosystem function. There is no evidence of a critically low turbidity level detrimental to these ecosystems; naturally low turbidity is characteristic of high ecological health in pristine alpine waters.

Related Benchmarks

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