Upper Mangaokewa
Catchment monitoring by King Country River Care commenced in May 2021 and covers between four to six monitoring sites sampled on a quarterly basis.
Waikato Regional Council (WRC) has one monitoring site at Lawrence St Bridge, Te Kuiti, which is monitored monthly.
A water quality baseline was calculated from the time the catchment group was formed using five years (Jan 2015 – Dec 2019) of monthly monitoring data, collected at the WRC site.
The location of the seven monitoring sites are shown on the map to the right.
Key Resources Being Lost from the Land
Monitoring results show the key resources being lost from the Upper Mangaokewa catchment in 2025 were Nitrogen, Sediment (reflected by low water clarity) and E. coli. Nitrogen was slightly elevated in three out of five sites and elevated in Mangawhauwhi stream. Suspended Sediment was slightly elevated at Lawrence Street Bridge and elevated the two Waiteti stream sites, while E. coli was elevated in four out of five sites. Loss of Sediment and Nitrogen represents a loss of soil and nutrients, while elevated E. coli represents a loss of organic matter and nutrients as it is largely associated with animal manure in rural catchments.
The water quality dials summarise the results collected in the Upper Mangaokewa catchment. The dial on the left shows the baseline for the catchment, covering 5 years of regional council monitoring at Lawrence Street Bridge in Te Kuiti. The dial on the right combines all data collected in 2025 at five sites, 27 samples in total. Arrows indicate either an increase or decrease in values compared to the sub-catchment baseline. An increase in water clarity is positive for river health while an increase in all other indicators may impair river health.
In 2025, indicators for phosphorus, nitrogen and water clarity/suspended sediment met water quality limits, while E. coli did not. Compared to the baseline – Water clarity was greater in 2025 and the concentration of dissolved reactive phosphorus and nitrogenwere lower.
Full Report Available to Download
Water quality dials for the Upper Mangaokewa catchment.
The bottom dial shows the sub-catchment baseline (2015-2019)
The top dial combines results collected in the 2025 monitoring period.
2025 Quarterly Summaries
February 2025
Water quality was Fair across all sites – Mangaokewa stream-viaduct (Site 4), Mangawhauwhi stream (Site 5), Waiteti stream-viaduct (Site 6) and Waiteti stream-upper (Site 46).
E. coli concentrations were low in Waiteti stream-upper (150 cells per 100 mL), slightly elevated in Mangaokewa stream (350 cells per 100 mL) and very high in Mangawhauwhi stream (2,000 cells per 100 mL) and Waiteti stream-viaduct (3,100 cells per 100 mL), exceeding recommended health guidelines for swimming (540 cells per 100 mL).
Nitrogen:
Nitrate concentrations were very low across all sites, falling well below ecological toxicity levels (2.4 mg/L) and Waikato, Plan Change One targets (0.525 mg/L). Mangawhauwhi stream had the lowest nitrate concentrations (0.08 mg/L) and Waiteti stream-viaduct had the highest concentrations (0.4 mg/L).
Ammonia concentrations were very low in Waiteti stream-viaduct (0.005 mg/L) and slightly higher in the other three sites, exceeding Plan Change One targets (0.005 mg/L).
Dissolved inorganic nitrogen (DIN) was also low across all sites (≤ 0.40 mg/L), falling below the ecological impact threshold (0.5 mg/L).Phosphorus:
Dissolved reactive phosphorus (DRP) concentrations were low in Waiteti stream (0.007 mg/L), slightly elevated in Mangaokewa stream-viaduct (0.012 mg/L) and Waiteti stream-upper (0.014 mg/L) and very high in Mangawhauwhi stream (0.022 mg/L).Suspended sediment/Water Clarity:
Water clarity was excellent in Mangaokewa stream and Mangawhauwhi stream (1.97 m), fair in Waiteti stream-viaduct (1.42 m) and poor Waiteti stream-upper (1.15 m), relative to the national bottom line (1.34 m).
The results in the table below have been graded according to the National Policy Statement for Freshwater Management (NPS-FM, 2020) and Waikato Plan Change One (PC1, 2020), using the strictest applicable measure.
Collection date: 18th February 2025
2025 Quarterly Summaries
May 2025
Water quality was Fair in Waiteti stream-viaduct (Site 6) and Waiteti stream-upper (Site 46), and Poor in Mangaokewa stream-viaduct (Site 4), Mangawhauwhi stream (Site 5).
E. coli concentrations were low in Waiteti stream-upper (150 cells per 100 mL), slightly elevated in Mangaokewa stream (370 cells per 100 mL) and elevated in Mangawhauwhi stream (550 cells per 100 mL) and Waiteti stream-viaduct (650 cells per 100 mL), exceeding recommended health guidelines for swimming (540 cells per 100 mL).
Nitrogen:
Nitrate concentrations were low in Waiteti stream (≤ 0.38 mg/L) and moderate in Mangaokewa stream (0.52 mg/L), falling well below ecological toxicity levels (2.4 mg/L) and Waikato Plan Change One targets (0.525 mg/L). Concentrations were moderate in Mangawhauwhi stream (0.76 mg/L) exceeding Waikato, Plan Change One targets (0.525 mg/L).
Ammonia concentrations were low in all sites (≤ 0.02 mg/L), posing a low risk to aquatic life. However, all sites exceeded Plan Change One targets (0.005 mg/L).
Dissolved inorganic nitrogen (DIN) was low in Waiteti stream (≤ 0.38 mg/L), and slightly elevated in Mangaokewa stream (0.52 mg/L) and Mangawhauwhi stream (0.76 mg/L), exceeding the ecological impact threshold (0.5 mg/L).Phosphorus:
Dissolved reactive phosphorus (DRP) concentrations were low in Waiteti stream-viaduct (0.009 mg/L) and Mangawhauwhi stream (0.01 mg/L), slightly elevated in Mangaokewa stream-viaduct (0.017 mg/L) and Waiteti stream-upper (0.013 mg/L).Suspended sediment/Water Clarity: Water clarity was Excellent in Mangawhauwhi stream (2.20 m), Good in Mangawkewa stream (1.69 m) and Waiteti stream-vaiduct (1.60 m) and Fair in Waiteti stream-upper (1.52 m), relative to the national bottom line (1.34 m).
The results in the table below have been graded according to the National Policy Statement for Freshwater Management (NPS-FM, 2020) and Waikato Plan Change One (PC1, 2020), using the strictest applicable measure.
Collection date: 15th May 2025
2025 Quarterly Summaries
August 2025
Water quality was Fair in Mangaokewa stream-viaduct (Site 4) and Waiteti stream-upper (Site 46), and Poor in Mangawhauwhi stream (Site 5) and Waiteti stream-viaduct (Site 6).
E. coli concentrations were very low in three sites (≤ 100 cells per 100 mL) and slightly elevated in Waiteti stream-viaduct (270 cells per 100 mL). All sites met recommended health guidelines for swimming (540 cells per 100 mL) and Mangawhauwhi stream and Waiteti stream-upper also met guidelines for livestock drinking water (< 100 cells per 100 mL) [1].
Nitrogen:
Nitrate concentrations were low in Waiteti stream-upper (0.33 mg/L) and slightly elevated across the other three sites, exceeding Waikato Plan Change One targets (0.525 mg/L). Though all sites fell well below ecological toxicity levels (2.4 mg/L).
Ammonia concentrations were very low at two sites, Mangaokewa stream and Waiteti stream-upper (< 0.005 mg/L) and slightly higher at Mangawhauwhi stream and Waiteti stream (0.006 – 0.01 mg/L) posing a low risk to aquatic life but exceeded Plan Change One targets (0.005 mg/L).
Dissolved inorganic nitrogen (DIN) was low in Waiteti stream-upper (0.33 mg/L), slightly elevated in Mangaokewa stream (0.84 mg/L) and Waiteti stream-viaduct (0.73 mg/L) and elevated in Mangawhauwhi stream (1.11 mg/L). Consequently, three quarters of all sites exceeding the ecological impact threshold (0.5 mg/L).Phosphorus:
Dissolved reactive phosphorus (DRP) concentrations were low across all sites (≤ 0.010 mg/L).Suspended sediment/Water Clarity:
Water clarity was Fair in Mangaokewa stream (1.52 m) and Poor across all other sites (≤ 1.17 m), relative to the national bottom line (1.34 m).
The results in the table below have been graded according to the National Policy Statement for Freshwater Management (NPS-FM, 2020) and Waikato Plan Change One (PC1, 2020), using the strictest applicable measure.
[1] Drinking water for livestock should contain < 100 cfu/100 mL (median value) of E. coli. Livestock Drinking Water Guidelines (2023), Australian & New Zealand Guidelines for Fresh & Marine Water Quality.
Sample Collection Day: 25th August 2025
2025 Quarterly Summaries
November 2025
Water quality was Fair in Waiteti stream-upper (Site 46), and Poor in Mangaokewa stream (Site 4), Mangawhauwhi stream (Site 5) and Waiteti stream-viaduct (Site 6).
E. coli concentrations were low in Waiteti stream-upper (150 cells per 100 mL), slightly elevated in Mangawahuwhi stream (370 cells per 100 mL), meeting recommended health guidelines for swimming (540 cells per 100 mL). Concentrations were elevated in Mangaokewa stream (630) and Waiteti stream-viaduct (710) and did not meet recommended swimming guidelines.
Nitrogen:
Nitrate concentrations were low in Waiteti stream-upper (0.20 mg/L) and slightly elevated across the other three sites, exceeding Waikato Plan Change One targets (0.525 mg/L). Though all sites fell well below eco-toxicity levels (2.4 mg/L).
Ammonia concentrations were very low at three sites, and slightly higher in Waiteti stream-viaduct (0.009 mg/L), posing a low risk to aquatic life but exceeded Plan Change One targets (0.005 mg/L).
Dissolved inorganic nitrogen (DIN) was very low in Waiteti stream-upper (0.20 mg/L) and slightly elevated in the other three sites (0.62 – 0.80 mg/L), exceeding the ecological impact threshold (0.5 mg/L).Phosphorus:
Dissolved reactive phosphorus (DRP) concentrations were low in Mangawhauwhi stream and Waiteti stream-viaduct (0.005 – 0.010 mg/L) and slightly elevated in Mangaokewa stream and Waiteti stream-upper (0.014 – 0.016 mg/L).Suspended sediment: Water clarity was Excellent in Mangaokewa stream (1.85 m), Fair in Mangawahuwhi stream (1.36 m) and Poor across all other sites (≤ 1.3 m), relative to the national bottom line (1.34 m).
The results in the table below have been graded according to the National Policy Statement for Freshwater Management (NPS-FM, 2020) and Waikato Plan Change One (PC1, 2020), using the strictest applicable measure.
Sample Collection Day: 12th November 2025
Upper Mangaokewa
Data & Downloads
->
Aquatic Biodiversity Summary
Biodiversity monitoring includes eDNA, collected by KCRC, and traditional biodiversity monitoring techniques (netting of freshwater invertebrates and netting and electrofishing of freshwater fish), by Waikato Regional Council (WRC). eDNA sampling has been done by KCRC, in autumn and winter in 2021, 2022 and 2023. WRC monitors most sites every 1 to 2 years, between November and March. If more than one results is available for any single monitoring location the results for that site are averaged across years.
Upper Mangaokewa
The upper Mangaokewa has high ecological value but shows some signs of stress.
The eDNA site had a high fish score but a low MCI score.
Across the catchment MCI scores were good at 3 out of 5 sites.
Rare native species of fish were detected, including lamprey, longfin eel and torrentfish.
No whitebait species were detected.
Three species of introduced fish detected, mosquito fish, brown trout and rainbow trout.
There is a clear migration pathway for native fish from the sea due to no dams being constructed on the Waipa River or Waikato River, downstream of lake Karapiro.
