Water Electrical Conductivity (EC)

AUS-TMS-AQU-WEC General Moderate confidence

Benchmark Value

1500 μS/cm

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

Contributing Benchmarks

OptimalRange Primary OptimalRange Guard MinimumOnly Guard MaximumOnly Guard Point Guard MinimumOnly Guard MaximumOnly Guard Point Guard OptimalRange Guard MaximumOnly Guard OptimalRange Guard MinimumOnly Guard MaximumOnly Guard

Evidence & Context

Upper Detrimental Threshold: EC levels exceeding approximately 1500 μS/cm are associated with adverse effects on freshwater biota and signify a transition to a degraded, salinized ecosystem state.

Metric Definition:

Water Electrical Conductivity (EC) as a measure of total dissolved salts in freshwater systems.

Benchmark Definition:

This benchmark marks the upper detrimental threshold of electrical conductivity beyond which freshwater ecosystems experience adverse effects and degradation due to salinization.

Justification:

A key review by Hart et al. (1991), cited in subsequent government assessments, concluded that aquatic biota will be adversely affected as salinity exceeds 1000 mg L−1, equivalent to approximately 1500 μS/cm.

Sources (1)

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

(PDF) 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.

A Compendium of Ecological Information on Australia's ... - DCCEEW

Contextual Support Government

A Compendium of Ecological Information on Australia's ... - DCCEEW

View Source

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

Regulatory Framework Journal

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

View Source

Context

Region Australia
Biome Tropical Monsoonal Savannas
Land Use Aquaculture
Assessment Not Stated
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 5 Jun 2026

Notes

Exceeding this threshold marks a fundamental shift away from a true freshwater ecosystem, including loss of sensitive species and reduction in biodiversity. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

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