2024 Quarterly Results
August 2024
Water quality was Fair. Dissolved inorganic nitrogen was slightly elevated at two sites and water clarity was poor across all sites.
E. coli concentrations were very low at all sites (≤ 110) with concentrations falling well within recommended health limits for swimming (540). Nitrate concentrations were low, falling well below ecological toxicity levels (2.4 mg/L) at all sites. Nitrates were lowest at 31-Oparau River (0.24 mg/L) and highest at 32-Mangapapa stream (0.57 mg/L). Ammonia concentrations were very low at all sites (< 0.005 mg/L). Dissolved inorganic nitrogen (DIN) was low at 2 sites (≤ 0.43 mg/L) but was slightly elevated at 32-Mangapapa stream (0.57 mg/L) and 33-Te Kauri Stream (0.51 mg/L). DIN concentrations greater than 0.5 mg/L can cause ecological impacts like excessive growth of algae and aquatic plants, and loss of sensitive species. Dissolved reactive phosphorus concentrations were very low at all sites (≤ 0.003 mg/L). Water clarity was poor at all sites (≤ 1.02 m), relative to the national bottom line (1.34 m). The Oparau River had the highest water clarity (≥ 1 m) while the Awaroa river had the lowest clarity (0.64 m).
Sample Collection Day: 22th August 2024
May 2024
Water quality was Good, except for dissolved inorganic nitrogen which was elevated at one site, and water clarity which was poor at another site.
E. coli concentrations were low at all sites (≤ 240) with concentrations falling well within recommended health limits for swimming (540). Nitrate concentrations were low, falling well below ecological toxicity levels (2.4 mg/L) at all sites. Nitrates were lowest at 31-Oparau River (0.07 mg/L) and highest at 32-Mangapapa stream (0.56 mg/L). Ammonia concentrations were low at all sites (< 0.01 mg/L). Dissolved inorganic nitrogen was low at 3 sites but slightly elevated at 32-Mangapapa stream (0.56 mg/L). Concentrations greater than 0.5 mg/L can cause ecological impacts like excessive growth of algae and aquatic plants, and loss of sensitive aquatic species. Dissolved reactive phosphorus concentrations were low at all sites (≤ 0.009 mg/L). Water clarity was excellent at 3 sites (≥ 1.84 m) but was poor at 33-Te Kauri stream (1.14 m), relative to the national bottom line (1.34 m). Awaroa river had the highest water clarity (2.5 m)
Collection date: 13th May 2024
February 2024
Water quality was Good, except for E.coli which was elevated at two sites.
E. coli concentrations were very low at two sites (≤ 130), slightly elevated at 33-Te Kauri stream (320) and very high at 32-Mangapapa stream (1,300). E. coli concentrations greater than 540 are above recommended levels for swimming due to increased risk of infection. Nitrate concentrations were low at all sites, falling well below levels where ecological toxicity impacts can occur (2.4 mg/L). Nitrate concentrations were lowest at 31-Oparau River (0.004 mg/L) and highest at 32-Mangapapa stream (0.41 mg/L). Ammonia concentrations were exceptionally low at all sites (< 0.005 mg/L). Dissolved inorganic nitrogen were low at all sites, falling below levels which can cause ecological impacts (< 0.5 mg/L) like excessive growth of algae and aquatic plants, and loss of sensitive aquatic invertebrates. Dissolved reactive phosphorus concentrations were exceptionally low at all sites (≤ 0.004 mg/L). Water clarity was excellent at 3 sites (≥ 1.84 m) and good at 32-Mangapapa stream (1.69 m), relative to the national bottom line (1.34 m). 34-Awaroa River had the highest water clarity (2.78 m).
Sample Collection Day: 14th February 2024
2023 Summary
Water samples were collected from 5 stream or river sites across the North Kawhia catchment in 2023. The sites are located on Oparau river, Mangapapa stream, Te Kauri stream and Awaroa river (all sampled quarterly), and Waikato Regional Council collects monthly samples from the Oparau river.
The below water quality dial for North Kawhia represents 27 individual samples and summaries the monitoring results from these 5 locations, collected between January 2023 – December 2023.
Suspended sediment was slightly elevated, which can impact ecological health. Nitrates and dissolved reactive phosphorus (DRP) were very low, which supports ecosystem health. E. coli was low, meeting human health standards for swimming. All attributes met national water quality limits.
Arrows indicate an increase or decrease in values compared to the baseline for Kawhia. No arrows indicate where there’s no deviation from baseline values. The baseline was calculated from 5 years of data collected by the council at the Oparau river monitoring site, between 2016 – 2020. An increase in water clarity is positive for river health, while an increase in all other attributes may impair river health.
North Kawhia Dial. 2023.
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.
Both North and South Kāwhia have significant freshwater biodiversity value, however, some sites are showing early signs of ecological stress.
Just under halve of freshwater invertebrate MCI scores are good.
The number of insect species detected from eDNA (an indicator for ecological health) were low in Te Kauri stream (North Kāwhia), 17 species and moderate in Puaroa stream (South Kāwhia), 39 species.
Fish communities were diverse across north and south Kāwhia.
Three whitebait species were detected, Giant kōkopu, Banded kōkopu and inanga.
Six species of threatened fish present, including lamprey, Īnanga, Giant kōkopu, Longfin eel, Redfin bully and Torrentfish.
Only 1 species of introduced fish was detected, brown trout.
2023 Quarterly Results
November 2023
Water quality was excellent at sites 31 and 34. Water quality was fair and site 32 due to elevated phosphorus and moderate water clarity. Water quality was good at site 33, except for water clarity which was low. E. coli concentrations were very low at all sites (≤ 200). Nitrate concentrations were below toxicity levels at all sites being lowest at 31-Oparau River (0.02 mg/L) and highest at 32-Mangapapa stream (0.50 mg/L). Ammonia concentrations were exceptionally low at all sites (< 0.005 mg/L). Mangapapa stream was the only site with a combined concentration of Nitrate + Ammonia equivalent to 0.5 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 exceptionally low at 3 out of 4 sites (≤ 0.006 mg/L) and elevated at 32-Mangapapa Stream (0.02 mg/L)). Water clarity was excellent at 31-Oparau River and 34-Awaroa River (≥ 2.31 m) but poor at 32-Mangapapa stream and 33-Te Kauri Stream (≤ 1.43 m), relative to the national bottom line (1.34 m).
Collection date: 10 November 2023
August 2023
Overall water quality was good except for water clarity which was low in 3 out of 4 sites. E. coli concentrations were very low at all sites (≤ 37). Nitrate concentrations were below toxicity levels at all sites being lowest at 31-Oparau River (0.25 mg/L) and highest at 32-Mangapapa stream (0.66 mg/L). Ammonia concentrations were low at all sites (≤ 0.01 mg/L). Sites 32 and 33 (Mangapapa stream and Te Kauri stream) had a combined concentration of Nitrate + Ammonia equivalent to 0.66 mg/L and 0.52 mg/L, respectively. 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 all 4 sites (≤ 0.01 mg/L). Water clarity was good at 31-Oparau River (2.19 m) but poor at the other three sites (≤ 1.45 m), relative to the national bottom line (1.34 m)
Sample Collection Day: 25th August 2023
May 2023
E. coli concentrations were low at all sites (≤ 120). Nitrate concentrations were below toxicity levels at all sites being lowest at 31-Oparau River (0.28 mg/L) and highest at 33-Te Kauri Stream (0.63 mg/L). Ammonia concentrations were exceptionally low at all sites (< 0.005 mg/L). Sites 32 and 33 (Mangapapa Stream and Te Kauri 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 low at 3 out of 4 sites (≤ 0.008 mg/L) and elevated at 34-Awaroa River (0.016 mg/L). Water clarity was poor at all sites (≤ 1.09 m), relative to the national bottom line (1.34 m).
Sample Collection Day: 18 May 2023
Water Quality Summary 2022
The water quality dial for North Kawhia combines data collected at 5 monitoring sites between January 2022 – February 2023, representing 28 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.
