Appendix 12: NOF Environmental Limits for Attributes for Freshwater Boffa Miskell Ltd | Waihi North Project: Freshwater Ecological Assessment | [Subject] Table 12-4: Environmental limits for dissolved oxygen for ecosystem health values in freshwater in New Zealand (from NPS-FM 2020). Table 7 – Dissolved oxygen Value (and component) Ecosystem health (Water quality) Freshwater body type Rivers (below point sources only) Attribute unit mg/L (milligrams per litre) Attribute band and description Numeric attribute state 7-day mea (summe 1 November n minimum 1-day minimum (summer r period: period: 1 November to 30th to 30th April) April) A ≥8.0 No stress caused by low dissolved oxygen on any aquatic organisms that are present at matched reference (near-pristine) sites. ≥7.5 B ≥7.0 and <8.0 Occasional minor stress on sensitive organisms caused by short periods (a few hours each day) of lower dissolved oxygen. Risk of reduced abundance of sensitive fish and macroinvertebrate species. ≥5.0 and <7.5 C ≥5.0 and <7.0 Moderate stress on a number of aquatic organisms caused by dissolved oxygen levels exceeding preference levels for periods of several hours each day. Risk of sensitive fish and macroinvertebrate species being lost. ≥4.0 and <5.0 National bottom line 5 .0 4.0 D <5.0 Significant, persistent stress on a range of aquatic organisms caused by dissolved oxygen exceeding tolerance levels. Likelihood of local extinctions of keystone species and loss of ecological integrity. <4.0 The 7-day mean minimum is the mean value of seven consecutive daily minimum values. The 1-day minimum is the lowest daily minimum across the whole summer period.
RkJQdWJsaXNoZXIy MjE2NDg3