Water Electrical Conductivity (EC)

AUS-TMS-URB-WEC General High confidence

Benchmark Value

20 µS/cm

Thresholds: Lower: 20, Upper: —

Direction: Higher is desirable ↑

Form: LowerThreshold

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

Contributing Benchmarks

OptimalRange Primary MaximumOnly Guard MaximumOnly Guard LowerThreshold Guard UpperThreshold Guard MaximumOnly Guard MaximumOnly Guard OptimalRange Guard UpperThreshold Guard LowerThreshold Guard OptimalRange Guard MaximumOnly Guard OptimalRange Guard UpperThreshold Guard

Evidence & Context

A critically low threshold is proposed at < 20 µS/cm.

Metric Definition:

Water Electrical Conductivity (EC) level below which essential ion availability may be compromised

Benchmark Definition:

Lower critical threshold of Electrical Conductivity (EC) below which physiological stress due to insufficient ions may occur in freshwater streams of the tropical monsoonal savanna biome under urban and developed land use.

Justification:

Waterways with EC consistently falling below this level could be considered to be in a critically low state, potentially unable to support healthy biotic communities adapted to the natural ionic composition of the region's waters.

Sources (1)

Preview of Water quality guidelines - Queensland Environment Department, accessed August 1, 2025,

Water quality guidelines - Queensland Environment Department, accessed August 1, 2025, Government

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

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

(PDF) Effects of increasing salinity on freshwater ecosystems in Australia - ResearchGate, accessed August 11, 2025,

Direct Evidence Journal

Effects of increasing salinity on freshwater ecosystems in Australia - ResearchGate

View Source

Preview of Water Quality Objectives for the Darwin Harbour Region - Background Document - Department of Lands, Planning and Environment, accessed July 16, 2025,

Water Quality Objectives for the Darwin Harbour Region - Background Document - Department of Lands, Planning and Environment, accessed July 16, 2025,

Direct Evidence Journal

Water Quality Objectives for the Darwin Harbour Region - Background Document - Department of Lands, Planning and Environment

View Source

Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Urban & Developed Use
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 19 Mar 2026

Notes

This threshold marks the start of the natural condition and ensures a sufficient baseline concentration of dissolved ions for essential biological function.

Related Benchmarks

Other benchmarks in the AUS-TMS-URB-WEC family.