Appendix 12: NOF Environmental Limits for Attributes for Freshwater Boffa Miskell Ltd | Waihi North Project: Freshwater Ecological Assessment | [Subject] Table 12-6: Environmental limits for dissolved reactive phosphorus for ecosystem health values in freshwater in New Zealand (from NPS-FM 2020). Table 20 – Dissolved reactive phosphorus Value (and component) Ecosystem health (Water quality) Freshwater body type Rivers Attribute unit DRP mg/L (milligrams per litre) Attribute band and description Numeric attribute state Median 95th percentile A Ecological communities and ecosystem processes are similar to those of natural reference conditions. No adverse effects attributable to dissolved reactive phosphorus (DRP) enrichment are expected. ≤ 0.006 ≤ 0.021 B Ecological communities are slightly impacted by minor DRP elevation above natural reference conditions. If other conditions also favour eutrophication, sensitive ecosystems may experience additional algal and plant growth, loss of sensitive macroinvertebrate taxa, and higher respiration and decay rates. > 0.006 and ≤0.010 > 0.021 and ≤0.030 C Ecological communities are impacted by moderate DRP elevation above natural reference conditions. If other conditions also favour eutrophication, DRP enrichment may cause increased algal and plant growth, loss of sensitive macro-invertebrate and fish taxa, and high rates of respiration and decay. > 0.010 and ≤ 0.018 > 0.030 and ≤ 0.054 D Ecological communities impacted by substantial DRP elevation above natural reference conditions. In combination with other conditions favouring eutrophication, DRP enrichment drives excessive primary production and significant changes in macroinvertebrate and fish communities, as taxa sensitive to hypoxia are lost. >0.018 >0.054 Numeric attribute state must be derived from the median of monthly monitoring over 5 years.
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