Water Turbidity

AUS-TSW-AQU-WTU General Low confidence

Benchmark Value

20 NTU

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 15 benchmarks together — the OptimalRange form drives the primary score, while 14 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Reference Value: <20 NTU

Metric Definition:

Water Turbidity measured in Nephelometric Turbidity Units (NTU), an optical measure of water clarity quantifying light scattering by suspended and dissolved materials.

Benchmark Definition:

This benchmark represents the upper limit of an optimal range for a best-practice aquaculture system.

Justification:

It is derived by synthesis from the Australian and New Zealand Guidelines for Fresh and Marine Water Quality (ANZECC/ANZG 2000), using the default trigger values for healthy, analogous ecosystems (lakes and upland rivers: 1-25 NTU) as the reference for "best available condition."

Sources (1)

National Guidelines for Water Quality | Department of Natural ..., accessed July 12, 2025, Journal

National Guidelines for Water Quality | Department of Natural ..., accessed July 12, 2025,

View Source

Context

Region Australia
Biome Temperate Semi-Arid Shrublands & Open Woodlands
Land Use Aquaculture
Assessment Not Stated
Evidence Type ReferenceCondition

Lifecycle

Status Superseded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

Notes

A direct measurement from a perfectly matched site is not available. The functional range for this indicator is defined by three thresholds: (1) A Lower Critical Threshold of <2 NTU, below which the system may be sterile and unproductive. (2) An Optimal Range of 5-20 NTU, which balances natural productivity with high water quality. (3) An Upper Detrimental Threshold of >50 NTU. This upper limit is based on the ANZECC guideline for lowland rivers and represents a point of management failure (e.g., algal blooms, high waste load) rather than the much higher physiological tolerance of native species like Murray Cod (>150 NTU). AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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