Water Turbidity

AUS-TMI-LVG-WTU General High confidence

Benchmark Value

5 NTU

Direction: Higher is desirable ↑

Form: Point

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 13 benchmarks together — the OptimalRange form drives the primary score, while 12 guard(s) constrain the result.

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard UpperThreshold Guard MinimumOnly Guard OptimalRange Guard Point Guard OptimalRange Guard UpperThreshold Guard MaximumOnly Guard LowerThreshold Guard OptimalRange Guard UpperThreshold Guard Point Guard

Evidence & Context

The proposed benchmark is therefore 5 NTU.

Metric Definition:

Water turbidity measured in Nephelometric Turbidity Units (NTU), representing the 80th percentile baseflow turbidity for 'Slightly Disturbed' upland fresh waters in Queensland's Wet Tropics region.

Benchmark Definition:

This benchmark represents the 80th percentile baseflow turbidity for 'Slightly Disturbed' upland fresh waters in Queensland's Wet Tropics region.

Justification:

This value is derived from the Queensland Government's Water Quality Objectives, which are based on extensive local reference site data and align with the national (ANZG 2018) water quality framework. The benchmark is corroborated by separate agricultural guidance recommending turbidity <5 NTU for stock water infrastructure.

Sources (1)

Preview of Tully River, Murray River and Hinchinbrook Island Basins Environmental Values and Water Quality Objectives

Tully River, Murray River and Hinchinbrook Island Basins Environmental Values and Water Quality Objectives Journal

Environmental Protection (Water and Wetland Biodiversity) Policy 2019: Tully, Murray and Hinchinbrook Island River Basins Environmental Values and Water Quality Objectives

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Barron River Basin Environmental Values and Water Quality ..., accessed July 21, 2025,

Direct Evidence Journal

Effects of total dissolved solids on growth and mortality predict ...

View Source

Wet Tropics basins - Queensland Environment Department, accessed July 21, 2025,

Direct Evidence Government

Barron River Basin Environmental Values and Water Quality ..., accessed July 30, 2025,

View Source

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Livestock Grazing & Pasture
Assessment Pristine Reference
Evidence Type ReferenceCondition

Lifecycle

Status Active
Version 1
Effective From 19 Mar 2026

Notes

The functional range analysis indicates: (1) no evidence for a lower critical threshold (clearer is better); (2) an optimal range of 2-5 NTU for a high-health system; and (3) an upper detrimental threshold of 15 NTU, above which a system is considered moderately disturbed.

Related Benchmarks

Other benchmarks in the AUS-TMI-LVG-WTU family.