Water Electrical Conductivity (EC)

AUS-TSR-LVG-WEC General Moderate confidence

Benchmark Value

No specific value — see range
Range: 750 to 900 μS/cm
Optimal Range: 750 to 900
Direction: Lower is desirable ↓
Form: OptimalRange

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

Evidence & Context

750 - 900 μS/cm: The onset of chronic, sub-lethal stress for the most sensitive bio-indicator species (mayflies). This represents the scientifically defensible start of direct ecological detriment.

Metric Definition:

Electrical Conductivity (EC) thresholds for aquatic ecosystem health

Benchmark Definition:

This benchmark represents the range of electrical conductivity values in freshwater where chronic sub-lethal effects begin to impact sensitive aquatic species in tropical and subtropical rainforest regions under livestock grazing and pasture land use.

Justification:

Laboratory research on Australian mayfly species found that chronic, sub-lethal effects and mortality begin to occur at EC levels as low as 900 μS/cm, with general tolerance around 750 μS/cm.

Sources (2)

Preview of (PDF) A review of the salt sensitivity of the Australian freshwater biota, accessed August 11, 2025,
(PDF) A review of the salt sensitivity of the Australian freshwater biota, accessed August 11, 2025, Journal

Salinity Tolerances of Freshwater Macroinvertebrates

View Source
Preview of Accessory Publication Relative salinity tolerance of macroinvertebrates from the Barwon River, Victoria, Australia
Accessory Publication Relative salinity tolerance of macroinvertebrates from the Barwon River, Victoria, Australia Journal

Pine Creek, near Dutton 2010 Aquatic Ecosystem Condition Report - EPA SA

View Source

Supporting Sources (2)

Additional references from the underlying research that informed this benchmark.

Preview of Effect of reduced grazing pressure on sediment and nutrient yields in savanna rangeland streams draining to the Great Barrier Reef - CSIRO Research Publications Repository
Effect of reduced grazing pressure on sediment and nutrient yields in savanna rangeland streams draining to the Great Barrier Reef - CSIRO Research Publications Repository
Direct Evidence Journal

Hillslope gully erosion in savanna rangelands tributary to the Great ..., accessed July 19, 2025,

View Source
Preview of Tully River, Murray River and Hinchinbrook Island Basins Environmental Values and Water Quality Objectives
Tully River, Murray River and Hinchinbrook Island Basins Environmental Values and Water Quality Objectives
Direct Evidence Journal

Environmental Protection (Water and Wetland Biodiversity) Policy 2019: Tully, Murray and Hinchinbrook Island River Basins Environmental Values and Water Quality Objectives

View Source

Context

  • Region Australia
  • Biome Tropical & Subtropical Rainforests
  • Land Use Livestock Grazing & Pasture
  • Assessment Pristine Reference
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 1
  • Effective From 20 Mar 2026

Notes

This range represents the scientifically defensible start of direct ecological detriment to sensitive bio-indicator species.

Related Benchmarks

Other benchmarks in the AUS-TSR-LVG-WEC family.

1500 μS/cm Moderate
Livestock Grazing & Pasture · Pristine Reference
MaximumOnly Active v1