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 2 benchmarks together — the OptimalRange form drives the primary score, while 1 guard(s) constrain the result.
Contributing Benchmarks
Evidence & Context
Natural background levels in pristine systems can be <0.01 – 0.02 mg/L NO3−; below this, N-limitation might occur in truly oligotrophic systems.
Lower critical threshold of water nitrate concentration below which nitrogen limitation might occur in aquatic ecosystems.
Lower critical threshold for nitrate concentration below which nitrogen limitation may impair aquatic primary productivity.
Based on natural background levels in pristine aquatic ecosystems and ecological understanding of nitrogen limitation in oligotrophic waters.
Sources (1)
ANZG (2018) Australian and New Zealand Guidelines for Fresh and Marine Water Quality
View SourceSupporting Sources (3)
Additional references from the underlying research that informed this benchmark.
Hickey, C. (2002). Nitrate guideline values in ANZECC 2000. Memorandum MFE02237 prepared for Ministry for the Environment (New Zealand). NIWA Client Report: HAM2002-126.
View Source
Palaeovalley Groundwater Resources in Arid and Semi-Arid Australia - Geoscience Australia, accessed July 31, 2025,
View Source
webcat.niwa.co.nz, accessed May 11, 2025
View Source