Water Turbidity

AUS-TDG-CON-WTU General Moderate confidence

Benchmark Value

50 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.

Evidence & Context

Values approaching or exceeding 50-100 NTU, even if episodic rather than persistent, can cause acute stress to aquatic organisms and lead to substantial habitat damage, particularly through sedimentation.

Metric Definition:

Water turbidity measured in Nephelometric Turbidity Units (NTU).

Benchmark Definition:

Lower limit of turbidity indicating acute ecological impact in Temperate Dry Woodlands & Native Grasslands conservation areas.

Justification:

Levels associated with acute stress, significant habitat damage (e.g., sedimentation), and high risk to aquatic diversity, even if not persistent.

Sources (1)

Feral horses (Equus caballus) increase suspended sediment in subalpine streams Journal

Feral horses (Equus caballus) increase suspended sediment in subalpine streams

View Source

Supporting Sources (3)

Additional references from the underlying research that informed this benchmark.

Default guideline values - Water Quality Australia, accessed August 12, 2025

Direct Evidence Government

ANZECC (2000) Australian and New Zealand Guidelines for Fresh and Marine Water Quality.

View Source

Preview of Upper Murrumbidgee Waterwatch Catchment Health Indicator Program (CHIP) Reports (e.g., 2021, 2023) and associated methodology defining "Excellent" water quality thresholds.

Upper Murrumbidgee Waterwatch Catchment Health Indicator Program (CHIP) Reports (e.g., 2021, 2023) and associated methodology defining "Excellent" water quality thresholds.

Direct Evidence Journal

Catchment Health Indicator Program - Upper Murrumbidgee Waterwatch

View Source

Yellow Box – Red Gum Grassy Woodland, accessed August 12, 2025,

Contextual Support Journal

Indicator W3: Water quality - ACT State of the Environment

View Source

Context

Region Australia
Biome Temperate Dry Woodlands & Native Grasslands
Land Use Conservation / Protected Natural Areas
Assessment Conservation Target
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 10 Jun 2026

Notes

Episodic turbidity above this level can cause acute impacts.

Related Benchmarks

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