Water Electrical Conductivity (EC)

AUS-AIF-URB-WEC General High confidence

Benchmark Value

500 μS/cm

Range: 125 to 500 μS/cm

Optimal Range: 125 to 500

Direction: Higher 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 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 benchmark of < 500 μS/cm is proposed as the reference value for high environmental health. This value is scientifically defensible for several converging reasons: Protection of Keystone Species: It is protective of the critical recruitment phase of Murray Cod, whose larvae are negatively impacted by salinities above this level. Ensuring the viability of keystone species' populations is fundamental to ecosystem health. Support for Diverse Communities: It falls well within the EC range where high-quality, sensitive macroinvertebrate communities (those with high SIGNAL2 scores) are found to persist. Alignment with "Good Quality" Water: It aligns with general water quality standards that classify water below 800 μS/cm as "good" for a range of human and agricultural uses, suggesting a high degree of utility and health. Technical Achievability: It is a realistic and achievable target in a well-managed urban context. Public water quality reports for Broken Hill, an arid city now supplied by the Murray River, show that the treated water entering the urban system consistently has an EC between 150 and 275 μS/cm. This demonstrates that water of this quality is technically achievable and is, in fact, the input into the very type of socio-ecological system under consideration. This benchmark represents a state that is not only protective of critical ecological functions but is also attainable through best-practice urban water management.

Metric Definition:

Water Electrical Conductivity (EC)

Benchmark Definition:

This benchmark represents the maximum electrical conductivity level in urban arid inland waterways that protects key ecological functions and supports high environmental health.

Justification:

The benchmark is based on the critical salinity threshold for the successful recruitment of Murray Cod, a keystone species in Australia's arid/semi-arid river systems. Research shows significant impacts on larvae above ~500-600 μS/cm. This value is well below the general ecosystem degradation threshold of 1500 μS/cm and the MDBA's management target of <800 μS/cm, representing a state of high ecological health. It is also above the potential lower critical threshold for ion deficiency of 125 μS/cm, which is the lower bound of the ANZG guideline range for lowland rivers. This creates an optimal management range of 125-500 μS/cm. The benchmark is technically achievable, as demonstrated by treated water quality in arid urban centres like Broken Hill.

Sources (1)

Preview of Salinity sensitivity in early life stages of an Australian freshwater fish, Murray Cod (Maccullochella peelii peelii Mitchell 1838) - University of Canberra Research Portal, accessed August 11, 2025,

Salinity sensitivity in early life stages of an Australian freshwater fish, Murray Cod (Maccullochella peelii peelii Mitchell 1838) - University of Canberra Research Portal, accessed August 11, 2025, GreyLiterature

Murray Cod (Maccullochella peelii peelii Mitchell 1838) - University of Canberra Research Portal

Water Electrical Conductivity (EC)

Benchmark Value

Scoring Curve

Contributing Benchmarks

Evidence & Context

Sources (1)

Supporting Sources (20)

Context

Lifecycle

Notes

Related Benchmarks