B-2 – Area 2 - Assessment of Environmental Effects 115 margins of error. Increases in major ions (such as sulphate) however, may be measurable. o groundwater uses will not be affected by WRS seepage to groundwater due to the small rate of discharge and the dilution available within the Waihi Basin aquifer. o catchment water from above the WRS will be captured and diverted around the WRS; o any changes in groundwater and surface water quality due to WRS discharges are expected to be sufficiently minor that they will not affect the ability for the Regional Council to manage the catchment to achieve net improvement in water quality across the region, nor will they adversely affect the values of the Mataura Stream. The effects of seepage from the WRS on groundwater and surface water users will be negligible and will not present a significant risk to human health or aquatic ecosystems due to the low rate of seepage, the distance of the users from the discharge area and the dilution available within the aquifers and stream.100 Water from the perched aquifer will be captured by the WRS toe seepage collection pond and pumped to the WTP for treatment prior to discharge to the Ohinemuri River. On remediation of the site, it is expected these flows will be re-established within the Unnamed Tributary.101 The WRS will result in additional recharge of approximately 5 to 10m3/day to the deep aquifer. This is a minor contribution and will not be expected to affect the overall groundwater flow regime towards the Mataura Stream.102 The loss of tributary flow to the Mataura Stream from the WRS gully is expected to range of 1 – 2% of the total Mataura Stream flow. Such reductions are considered unlikely to be discernible from the background variability in flow and there are no existing takes from the Mataura Stream that could be impacted.103 Similar to the above, the loss of baseflow to the Mataura Stream as a result of dewatering activities associated with the Willows Farm Access Tunnel will not be discernible.104 Accordingly, the reasonably foreseeable range of groundwater and 100 Objective 3.1.2(o), Section 3.1, Waikato Regional Plan. 101 Objective 3.1.2(e), Section 3.1, Waikato Regional Plan. 102 Objective 3.1.2(e) and (g), Section 3.1, Waikato Regional Plan. 103 Objective 3.1.2(e) and (g), Section 3.1, Waikato Regional Plan. 104 Objective 3.1.2(e) and (g), Section 3.1, Waikato Regional Plan.
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