| Variable | Method | Detection limit |
|---|---|---|
| Nitrate + nitrite nitrogen | Total oxidised nitrogen. Automated cadmium reduction, Flow injection analyser. APHA 4500-NO3- I (Modified) 22nd Ed. 2012 | 0.001 mg/L |
| Nitrite nitrogen | Automated Azo dye colorimetry, Flow injection analyser. APHA 4500-NO3- I (Modified) 22nd Ed. 2012 | 0.002 mg/L |
| Nitrate nitrogen | Calculation: (Nitrate-N + Nitrite-N) - Nitrite-N | 0.001 mg/L |
| E. coli | APHA 9222G 22nd Ed. 2012 | 1 cfu/100mL |
| Dissolved arsenic | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.001 mg/L |
| Dissolved calcium | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.05 mg/L |
| Dissolved chromium | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.0005 mg/L |
| Dissolved iron | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.02 mg/L |
| Dissolved manganese | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.0005 mg/L |
| Dissolved magnesium | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.02 mg/L |
| Dissolved lead | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.0001 mg/L |
| Dissolved reactive phosphorus | Filtered sample, Molybdenum blue colourimetry. Flow injection analyser. APHA 4500-P G (modified) 23rd ed. 2017 | 0.004 mg/L |
| Dissolved potassium | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.05 mg/L |
| Dissolved sodium | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.02 mg/L |
| Dissolved zinc | Filtered sample, ICP-MS, trace level. APHA 3125 B 23rd ed. 2017 | 0.001 mg/L |
| Bicarbonate | Calculation: from alkalinity and pH. APHA 4500-CO2 D 23rd ed. 2017 | 1.0 mg/L |
| Chloride | Filtered sample, Ion Chromatography. APHA 4110 B (modified) 23rd ed. 2017 | 0.5 mg/L |
| Sulphate | Filtered sample, Ion Chromatography. APHA 4110 B (modified) 23rd ed. 2017 | 0.5 mg/L |
| pH | pH meter. APHA 4500-H+ B 23rd ed. 2017 | 0.1 pH units |
| Total alkalinity | Titration to pH 4.5 (M-alkalinity), autotitrator. APHA 2320 B (modified for Alkalinity <20) 23rd ed. 2017 | 1.0 mg/L as CaCO3 |
The Greater Wellington Natural Resources Plan (Chapter 4) provides management categories for differing levels of hydraulic connectivity of groundwater to surface water. See section 2.3 of Wairarapa Valley groundwater resource investigation for more detail.
Category A includes areas of the hydrogeological system which exhibit direct connectivity with surface water. Stream flow depletion occurs shortly following the commencement of groundwater abstraction with the depletion effect increasing to a level close to the overall pumping rate and dissipating quickly once pumping stops. As a consequence, a high proportion of the overall volume of groundwater pumped effectively represents induced flow loss from local surface waterways. Due to the immediacy of impact, groundwater abstraction from Category A aquifers can be considered analogous to direct surface water abstraction and managed in terms of the environmental flow and water level regimes established for hydraulically connected surface waterbodies.
Category B includes those areas of the hydrogeological system where groundwater abstraction may potentially result in significant impacts on surface water but where pumping regulation does not always provide an effective option for mitigating direct stream depletion effects. Category B represents the transition between indirect and direct stream depletion effects where it may be appropriate to manage groundwater takes in terms of either surface water or groundwater allocation depending on localised factors (e.g. local aquifer hydraulic parameters, abstraction rate and location of pumping with respect to surface waterbodies).
Category C covers those areas of the hydrogeological system where groundwater abstraction may contribute to an overall reduction in baseflow discharge at a catchment scale but where active regulation of pumping does not provide effective mitigation of potential effects on surface water. Cumulatively, these takes are more appropriately managed at a catchment or sub-catchment scale through the establishment of volumetric abstraction limits.
During the 2022/23 monitoring period, five wells had missed samples. Brief explanations are listed below:
One saline intrusion monitoring well was not monitored in the 2022/23 monitoring period.
Three wells have been added to the saline intrusion monitoring network:
Previous changes to Groundwater Quality State of the Environment (GQSoE) network and monitoring frequency: