Water Turbidity

AUS-ASC-CON-WTU General High confidence

Benchmark Value

2 NTU

Thresholds: Lower: —, Upper: 2

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 6 benchmarks together — the OptimalRange form drives the primary score, while 5 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard MaximumOnly Guard MaximumOnly Guard OptimalRange Guard MaximumOnly 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 measured in Nephelometric Turbidity Units (NTU), indicating the cloudiness or haziness of water caused by suspended particulate matter.

Benchmark Definition:

This benchmark represents the maximum water turbidity level in NTU that reflects the best available natural condition in the Australian Alpine and Subalpine Conservation Areas, indicating very clear water with minimal disturbance.

Justification:

The benchmark is derived from multiple monitoring sites within Kosciuszko National Park, demonstrating high environmental health with consistently very low turbidity levels.

Sources (1)

NSW alpine resorts environmental performance report 2020–21 Journal

NSW Alpine Resorts Environmental Performance Report 2020–21

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

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

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

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 - Water and ..., accessed August 10, 2025

View Source

Context

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

Lifecycle

Status Active
Version 1
Effective From 17 Mar 2026

Notes

The reference value is often below 1 NTU, reflecting minimal anthropogenic disturbance and healthy ecosystem function. There is no evidence of a critically low turbidity level detrimental to these ecosystems; any increase from this baseline indicates disturbance. The ANZECC 2000/ANZG 2018 guidelines suggest a default trigger range of 2–25 NTU for upland rivers, but alpine sites have much lower thresholds.

Related Benchmarks

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