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 13 benchmarks together — the OptimalRange form drives the primary score, while 12 guard(s) constrain the result.
Evidence & Context
The ANZG framework recommends the 95% species protection level for assessing slightly-to-moderately disturbed ecosystems. This level appropriately reflects the goal for a well-managed urban system: one that is not pristine but is managed to maintain a high degree of ecological integrity and protect almost all species. Therefore, the DGV for 95% species protection in hard water, 29 mg/L as NO3−−N, is the most scientifically defensible upper detrimental threshold.
Concentration of nitrate-nitrogen (NO3−−N) in freshwater as a toxicant to aquatic ecosystems
This benchmark represents the upper detrimental threshold concentration of nitrate-nitrogen in hard water typical of the Arid Mountain Ranges & Uplands urban areas, protecting 95% of aquatic species from chronic toxic effects.
This value is derived from the ANZG (2025) Default Guideline Values for nitrate as a toxicant, selected for hard water conditions typical of the biome, and the 95% species protection level appropriate for slightly-to-moderately disturbed urban systems.
Sources (1)
Toxicant default guideline values for aquatic ecosystem protection: Nitrate in freshwater - Water Quality Australia
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Additional references from the underlying research that informed this benchmark.
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