Water Electrical Conductivity (EC)

AUS-TMS-URB-WEC General High confidence

Benchmark Value

1500 µS/cm

Thresholds: Lower: —, Upper: 1500

Direction: Lower is desirable ↓

Form: UpperThreshold

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 clear upper detrimental threshold is identified at approximately 1500 µS/cm, a level at which widespread, significant adverse impacts on Australian freshwater biota are documented.

Metric Definition:

Water Electrical Conductivity (EC) level indicating significant salinization stress and ecological harm

Benchmark Definition:

Electrical Conductivity (EC) threshold above which significant ecological harm occurs due to salinization in freshwater streams of the tropical monsoonal savanna biome under urban and developed land use.

Justification:

Multiple reviews and studies conclude that major adverse effects on a broad suite of freshwater biota become apparent as salinity exceeds this level, representing a critical tipping point for many freshwater communities.

Sources (1)

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

Effects of increasing salinity on freshwater ecosystems in Australia - ResearchGate

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

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

Direct Evidence Government

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

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

Above this level, reduced biodiversity, suppressed growth and reproduction in plants, and mortality of sensitive invertebrates and juvenile fish are expected.

Related Benchmarks

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