2023 Quarterly results
November 2023
Water quality was excellent at all four sites. E. coli concentrations were very low all sites (≤ 190). Nitrate concentrations were well below toxicity levels at all sites being lowest at 36-Puaroa Stream (0.11 mg/L) and highest at 38-Mangatangi Stream (0.20 mg/L). Ammonia concentrations were exceptionally low at all sites (≤ 0.007 mg/L). The combined concentration of Nitrate + Ammonia was below 0.5 mg/L at all sites. Ecological impacts, including problematic growth of algae and/or aquatic plants and loss of sensitive aquatic invertebrates may occur when the combined concentration of nitrate and ammonia regularly exceed 0.5 mg/L. Dissolved reactive phosphorus concentrations were exceptionally low at all 4 sites (≤ 0.005 mg/L). Water clarity was excellent at all sites relative to the national bottom line (0.61 m). 37-Oteke Stream had the highest water clarity (2.45 m) and 35-Nghuinga Stream had the lowest (1.61 m).
Collection date: 10 November 2023
August 2023
Overall water quality was good at 3 out of 4 sites. 38-Mangaohuinga Stream showed signs of impact indicated by higher concentrations of E. coli and dissolved reactive phosphorus. E. coli concentrations were very low at 3 out of 4 sites (≤ 87) and elevated at 38-Mangaohuinga Stream (660). Nitrate concentrations were below toxicity levels at all sites being lowest at 35-Nghuinga Stream (0.37 mg/L) and highest at 38-Mangaohuinga Stream (0.78 mg/L). Ammonia concentrations were low at all sites (≤ 0.009 mg/L). 38-Mangaohuinga Stream had a combined concentration of Nitrate + Ammonia equivalent to 0.79 mg/L. Ecological impacts, including problematic growth of algae and/or aquatic plants and loss of sensitive aquatic invertebrates may occur when the combined concentration of nitrate and ammonia regularly exceed 0.5 mg/L. Dissolved reactive phosphorus concentrations were low at 3 out of 4 sites (≤ 0.008 mg/L) and elevated at 38- Mangaohuinga Stream (0.012 mg/L). Water clarity was good at all sites relative to the national bottom line (0.61 m). 37-Oteke Stream had the highest water clarity (1.39 m) and lowest at 38-Mangatangi Stream (0.80 m).
Sample collection day: 25 August 2023
May 2023
E. coli concentrations were low at 3 out of 4 sites and elevated at 38-Mangatangi Stream (730). Nitrate concentrations were below toxicity levels at all sites being lowest at 36-Puaroa Str-Owhiro valley (0.33 mg/L) and highest at 38-Mangatangi Stream (0.78 mg/L). Ammonia concentrations were exceptionally low at all sites (≤ 0.005 mg/L). 38-Mangatangi Stream had a combined concentration of Nitrate and Ammonia exceeding 0.5 mg/L. Ecological impacts, including problematic growth of algae and/or aquatic plants and loss of sensitive aquatic species are likely when the combined concentration of nitrate and ammonia regularly exceed 0.5 mg/L. Dissolved reactive phosphorus concentrations were exceptionally low at 3 out of 4 sites (≤ 0.007 mg/L) and elevated at 38-Mangatangi Stream (0.014 mg/L). Water clarity was good at all sites and exceptionally good at 37-Oteke Stream (2.53 m), relative to the national bottom line (0.61 m).
Collection date: 18 May 2023
Water Quality Summary 2022
The water quality dial for South Kawhia combines data collected at 4 monitoring sites between January 2022 – February 2023, representing 16 individual samples. Nitrates and dissolved reactive phosphorus (DRP) were low, while water clarity was high indicating low concentrations of suspended sediment. E. coli was elevated. Arrows indicate an increase or decrease in values compared to the sub-catchment baseline (2016 – 2020). An increase in water clarity is positive for river health while an increase in all other attributes may impair river health.
