2023 Quarterly Summaries
November 2023
Water quality was variable between sites, ranging from good to poor due to elevated E. coli, nitrogen and suspended sediment. E. coli concentrations were low at two sites (140) and elevated at two sites (≥ 330). Nitrate concentrations were below toxicity levels at all sites but exceeded regional PC1 targets (0.525 mg/L) at 2 out of 4 sites (between 0.56 – 0.70 mg/L). Nitrate concentrations were lowest at 46-Waiteti Stream-Upper (0.09 mg/L) and highest at 5-Mangawhauwhi Stream (0.70 mg/L). Ammonia concentrations were low at 4-Mangaokewa Stream (viaduct) and exceeded PC1 targets (0.005 mg/L) at 3 out of 4 sites (≥ 0.006 mg/L). Two out of four sites had a dissolved inorganic nitrogen concentration exceeding 0.5 mg/L, potentially impacting river health. Dissolved reactive phosphorus concentrations were low at all sites (≤ 0.009 mg/L). Water clarity was excellent at 4-Mangaokewa Stream (2.25 m) and poor at all other sites (between 1.08 m - 1.24 m), relative to the national bottom line (1.34 m).
Collection date: 14 November 2023
September 2023
Overall, water quality was poor at most sites except for site 46-Waiteti stream-Upper, which had good water quality. Poor water quality was associated with elevated concentrations of E. coli, nitrogen and suspended sediment. E. coli concentrations were very low at 46-Waiteti Stream-Upper (52) and were elevated at all other sites (≥ 280). Nitrate concentrations were below toxicity levels at all sites but exceeded regional PC1 targets (0.525 mg/L) at 3 out of 4 sites (between 0.54 – 0.87 mg/L). Nitrate concentrations were lowest at 46- Waiteti Stream-Upper (0.17 mg/L) and highest at 5-Mangawhauwhi Stream (0.87 mg/L). Ammonia concentrations exceeded PC1 targets (0.005 mg/L) at all sites (between 0.009 – 0.03 mg/L). Ammonia concentrations were lowest at 4-Mangaokewa stream-viaduct and 46-Waiteti stream-upper and highest at 6- Waiteti Stream-viaduct (0.03 mg/L). Three out of four sites had a dissolved inorganic nitrogen concentration exceeding 0.5 mg/L, potentially impacting the health of the river. Dissolved reactive phosphorus concentrations were low at all sites (≤ 0.008 mg/L). Water clarity was poor at all sites (between 0.69 m - 1.47 m), relative to the national bottom line (1.34 m).
Collection date: 12 September 2023
May 2023
E. coli concentrations were low at five sites (≤ 240) and elevated at 6-Waiteti Stream-viaduct (470). Nitrate concentrations were below toxicity levels at all sites but exceeded regional PC1 targets (0.525 mg/L) at 4 out of 6 sites (between 0.53 – 0.93 mg/L). Nitrate concentrations were lowest at 46-Waiteti Stream Upper (0.25 mg/L) and highest at 5-Mangawhauwhi Stream (0.93 mg/L). Ammonia concentrations were exceptionally low at 3 out of 6 sites (≤ 0.005 mg/L) and exceeded PC1 targets (0.005 mg/L) at the other 3 sites being highest at 6-Waiteti Stream-viaduct (0.05 mg/L). Four out of six sites had a dissolved inorganic nitrogen concentration exceeding 0.5 mg/L, potentially impacting the health of the river. Dissolved reactive phosphorus concentrations were low at 3 sites (≤ 0.008 mg/L) and elevated at 3 sites being highest at 4-Mangaokewa Stream (viaduct) and 45-Mangaokewa Stream (0.013 mg/L). Water clarity was poor at all six sites (between 0.56 m - 1.20 m), relative to the national bottom line (1.34 m).
Collection date 8 May 2023.
February 2023
Water Quality Summary 2022
The water quality dial for Upper Mangaokewa combines data collected at 7 monitoring sites between January – December 2022, representing 30 individual samples. Dissolved reactive phosphorus (DRP) was low. E. coli was elevated, while water clarity was low indicating high sediment loading. Nitrate was above the Waikato PC1 target value (0.525 mg/L). Arrows indicate an increase or decrease in values compared to the sub-catchment baseline (2015 – 2020). An increase in water clarity is positive for river health while an increase in all other attributes may impair river health.
