WQI scores were used to categorise the CCC sites as being ‘very poor’ (0 – 39.9), ‘poor’ (40 – 69.99), ‘fair’ (70 – 79.9), ‘good’ (80 – 89.9) or ‘very good (90 – 100).
Below are 2021 Water Quality Index (WQI) scores, categories, and direction of significant temporal trends (2016–2021) at each of the Christchurch City Council surface water quality monitoring sites on the river
Source: CCC – Comprehensive Stormwater Network Discharge: Annual Report (2022) Appendix F – Annual Surface Water Quality Report-pages-22-24
Note: This Water Quality Index (WQI) was developed in 2013 for the CCC monthly monitoring sites, based on a Canadian WQI. The parameters used in the CCC WQI were copper, zinc, pH, TSS, DO, temperature, BOD5, total ammonia, nitrate, DRP and E. coli.