Water Electrical Conductivity (EC)

AUS-TMI-URB-WEC General Low confidence

Benchmark Value

280 μS/cm

Thresholds: Lower: —, Upper: 280

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

Research shows negative impacts on sensitive biota at levels as low as ~280 μS/cm.

Metric Definition:

Water Electrical Conductivity (EC) is a measure of water's capacity to conduct an electrical current, a property that is directly proportional to the concentration of total dissolved ionic substances, or salts.

Benchmark Definition:

This benchmark represents the upper electrical conductivity level in water above which negative impacts on sensitive aquatic biota are observed in tropical and subtropical maritime island urban environments in Australia.

Justification:

Elevated EC is a definitive indicator of degradation from urban pollution (wastewater, stormwater) and/or saltwater intrusion. The negative impacts occur through multiple mechanisms including osmotic stress and pollution.

Sources (1)

Norfolk Island Water Quality Assessment - CSIRO Research Publications Repository, accessed August 4, 2025, Government

Norfolk Island Water Quality Assessment - CSIRO Research Publications Repository

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Supporting Sources (7)

Additional references from the underlying research that informed this benchmark.

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

Contextual Support Journal

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

View Source

Preview of Diatom–water quality thresholds in South Australian streams indicate a need for more stringent water quality guidelines - CSIRO PUBLISHING | Marine and Freshwater Research, accessed May 15, 2025,

Diatom–water quality thresholds in South Australian streams indicate a need for more stringent water quality guidelines - CSIRO PUBLISHING | Marine and Freshwater Research, accessed May 15, 2025,

Contextual Support Journal

Diatom0water quality thresholds in South Australian streams indicate a need for more stringent water quality guidelines - CSIRO PUBLISHING | Marine and Freshwater Research

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Environmental Protection (Water and Wetland Biodiversity) Policy 2019 - Queensland Legislation

Regulatory Framework Government

Environmental Protection (Water and Wetland Biodiversity) Policy 2019 - Queensland Legislation

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Preview of Moreton Bay, North Stradbroke, South Stradbroke, Moreton and Moreton Bay Islands Environmental Values and Water Quality Objectives (June 2022)

Moreton Bay, North Stradbroke, South Stradbroke, Moreton and Moreton Bay Islands Environmental Values and Water Quality Objectives (June 2022)

Direct Evidence Journal

Moreton Bay, North Stradbroke, South Stradbroke, Moreton and Moreton Bay Islands Environmental Values and Water Quality Objectives (June 2022)

View Source

National Guidelines for Water Quality - Department of Natural Resources and Environment Tasmania, accessed August 1, 2025,

Methodology Source

Australian and New Zealand Guidelines for Fresh and Marine Water ...

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Urbanization Effects on Watershed Hydrology and In-Stream Processes in the Southern United States - MDPI

Contextual Support Journal

Urbanization Effects on Watershed Hydrology and In-Stream Processes in the Southern United States - MDPI

View Source

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

Contextual Support Government

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

View Source

Context

Region Australia
Biome Tropical & Subtropical Maritime Islands
Land Use Urban & Developed Use
Assessment Pristine Reference
Evidence Type DegradationThreshold

Lifecycle

Status Active
Version 1
Effective From 25 Mar 2026

Notes

Lower Boundary: A lower critical threshold is not applicable; lower EC values approaching that of rainwater indicate higher purity and ecological health. Optimal Range: The optimal range corresponds to the natural variability of minimally disturbed reference streams (e.g., between the 20th and 80th percentiles), but a numerical range cannot be specified due to the data gap.

Related Benchmarks

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