Water Nitrate
Benchmark Value
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 11 benchmarks together — the OptimalRange form drives the primary score, while 10 guard(s) constrain the result.
Evidence & Context
Draft ANZG 2025 guidelines indicate chronic effects on sensitive species may begin around 1.6 mg/L as NO3−, with the 95% species protection level (a common regulatory target for slightly disturbed systems) at approximately 7.1 mg/L as NO3−.
Upper detrimental threshold concentration of nitrate (mg/L as NO3−) causing toxic effects to aquatic species
This benchmark represents the nitrate concentration at which toxic effects begin for 5% of species in slightly to moderately disturbed freshwater systems in tropical monsoonal savannas under industrial land use.
This threshold is based on draft national guidelines derived from ecotoxicological data and species sensitivity distributions, representing a scientifically robust detrimental limit.
Sources (1)
Water Quality Objectives for the Darwin Harbour Region - Background Document - Department of Lands, Planning and Environment
View SourceSupporting Sources (5)
Additional references from the underlying research that informed this benchmark.
Australian Drinking Water Guidelines (ADWG)
View SourceNitrate in freshwater, toxicant default guideline values for protecting aquatic ecosystems, technical brief
View SourceANZG (2018) Australian and New Zealand Guidelines for Fresh and Marine Water Quality
View Source
Water Quality Objectives for the Darwin Harbour Region
View SourceSediments and nutrients in north Queensland tropical streams: changes with agricultural development and pristine condition status (Technical Report No. 62, Australian Rainforest CRC, 2006)
View Source