Water Turbidity

AUS-AKW-IND-WTU General Low confidence

Benchmark Value

50 NTU
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 9 benchmarks together — the OptimalRange form drives the primary score, while 8 guard(s) constrain the result.

Contributing Benchmarks

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

Evidence & Context

A persistent turbidity level above 50 NTU in pooled water between flow events would strongly indicate an unnatural chronic sediment source and a degraded ecological state.

Metric Definition:

Upper detrimental threshold of water turbidity indicating chronic sediment input and ecological degradation

Benchmark Definition:

This benchmark represents the maximum turbidity level beyond which chronic sediment input causes habitat degradation and reduced primary productivity in the biome under industrial land use.

Justification:

Persistent high turbidity reduces light for photosynthesis, smothers benthic habitats and spawning grounds, clogs gills, and reduces feeding efficiency for visual predators.

Sources (1)

Preview of Australia's inland waters - Water Quality Australia
Australia's inland waters - Water Quality Australia Government

Australia's inland waters - Water Quality Australia, accessed July 26, 2025

View Source

Supporting Sources (1)

Additional references from the underlying research that informed this benchmark.

Preview of A review of water quality studies relevant to northern Australia - CSIRO, accessed July 21, 2025,
A review of water quality studies relevant to northern Australia - CSIRO, accessed July 21, 2025,
Direct Evidence Journal

Salinity and water quality

View Source

Context

  • Region Australia
  • Biome Arid Karstic Woodlands & Shrublands
  • Land Use Industrial & Infrastructure Use
  • Assessment Not Stated
  • Evidence Type DegradationThreshold

Lifecycle

  • Status Active
  • Version 2
  • Effective From 4 Jun 2026

Notes

This threshold applies to non-flow conditions; natural flood pulses can be much higher. AssessmentContext defaulted to 'Not Stated' because the source document did not state one.

Related Benchmarks

Other benchmarks in the AUS-AKW-IND-WTU family.

5 NTU Low
Industrial & Infrastructure Use · Not Stated
MinimumOnly Active v1
— NTU Low
Industrial & Infrastructure Use · Not Stated
OptimalRange Active v1
20 NTU Low
Industrial & Infrastructure Use · Not Stated
MaximumOnly Superseded v1