Analytical methods

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

Groundwater connectivity

Proposed 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: Direct hydraulic connectivity

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: High hydraulic connectivity

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: Moderate to low hydraulic connectivity

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.

Sampling notes

During the 2018/19 monitoring period, six wells were only sampled two or three times. Brief explanations as to why wells could not be sampled are included below:

Additional sampling information for the 2018/19 monitoring period.

Four bores have been officially removed from the Groundwater Quality State of the Environment network due to loss of access.