Water Turbidity

AUS-ASC-AGR-WTU General Low confidence

Benchmark Value

25 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 9 benchmarks together — the OptimalRange form drives the primary score, while 8 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

Values exceeding > 25 NTU indicate significant degradation and a departure from acceptable conditions for upland rivers.

Metric Definition:

Water turbidity measured in Nephelometric Turbidity Units (NTU) representing the cloudiness or haziness of water caused by suspended particulate matter.

Benchmark Definition:

This benchmark defines an upper detrimental threshold of 25 NTU for water turbidity, above which significant ecological degradation is indicated in alpine and subalpine agricultural catchments.

Justification:

The 25 NTU level is the upper ANZECC guideline for upland rivers and indicates a significantly degraded aquatic environment and poor land management practices.

Supporting Sources (6)

Additional references from the underlying research that informed this benchmark.

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria 21

Contextual Support Journal

An Examination of Stream Water Quality Data from Monitoring of Forest Harvesting in the Eastern Highlands of Victoria 21

View Source

ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia, accessed August 12, 2025

Direct Evidence Government

ANZECC & ARMCANZ (2000) guidelines - Water Quality Australia

View Source

Australian and New Zealand Guidelines for Fresh and Marine Water Quality (2000), accessed May 11, 2025,

Direct Evidence Journal

Northern Territory Government (2020) Darwin Harbour Region Water Quality Objectives, Report Card Section 3.0.

View Source

Preview of Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management - PubMed Central, accessed July 16, 2025,

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management - PubMed Central, accessed July 16, 2025,

Direct Evidence Journal

Determining Tipping Points and Responses of Macroinvertebrate Traits to Abiotic Factors in Support of River Management. Water, 15(8), 1589.

View Source

NSW alpine resorts environmental performance report 2020–21

Direct Evidence Journal

NSW Alpine Resorts Environmental Performance Report 2020–21

View Source

Regenerative agriculture – Case studies from Western Australia, accessed May 13, 2025

Direct Evidence

Soil management guides - NSW Department of Primary Industries

View Source

Context

Region Australia
Biome Alpine and Subalpine Complex
Land Use Agricultural Crop Production
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 2
Effective From 3 Jun 2026

Notes

Values consistently exceeding 25 NTU clearly indicate a significantly degraded aquatic environment and point to serious issues with land management practices or major erosion events within the catchment. AssessmentContext defaulted to 'Not Stated' because the source document did not state one. Pipeline quarantine: Lower confidence than existing active benchmark v1 (Moderate). Accepted by operator on 2026-06-03 02:42 UTC — superseded v4 (#1382)

Related Benchmarks

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