15. Resource Quality (Water, Air, Soil) Volume One (ii) the degree of non-compliance will not give rise to significant adverse effects. If discharge to water is the best practicable option, compliance with the specified water quality classification standards will ensure that the quality of water is sufficient to sustain the natural and human values currently supported by the waterbody or coastal waters. Any point source discharge requiring a discharge permit will generally only be approved if the applicant has demonstrated that the effects of the discharge will comply with the specified water quality classification standards beyond a zone of reasonable mixing. There are limited circumstances where non-compliance with water quality classification standards will result in the approval of the discharge permit application; these circumstances are identified in (b) of the policy. In some circumstances, it will be necessary to take into account other influences on water quality upstream of the discharge point in applying this policy. For example, the receiving waters may already be in a state in which means the water quality standards are not being met. This is reflected in the ability to take into account the degree of additional adverse effect created by the discharge in (b)(ii). There is an expectation that the effects of the discharge on the quality of the receiving waters will be monitored to establish compliance with the water quality classifications standards over the life of the discharge permit. Compliance will be established by sampling/measuring relevant water quality parameters beyond the zone of reasonable mixing. In rivers, the parameters should also be measured upstream of the zone of reasonable mixing to establish background water quality. This policy assists to give effect to Policy A3 of the NPSFM and Policy 23 of the NZCPS. Policies 15.1.14 and 15.1.15 provide guidance on determining the size of an appropriate mixing zone. [R] Policy 15.1.13 – Where it is proposed to discharge contaminants to water upstream of any registered community drinking water supply providing for more than 501 people, have regard to the effect of the proposed discharge on the quality of water within the river and its subsequent suitability for human consumption after existing treatment. The NES for Sources of Human Drinking Water introduced requirements for the consideration of discharge permit applications upstream of abstraction points for community water supplies registered in accordance with Section 69J of the Health Act 1956. Regulations 7 and 8 of the NES specify circumstances when resource consent must not be granted. This policy compliments the regulations by ensuring regard is had to the effect of the proposed discharge on the suitability of the water for human consumption following existing treatment. Regulations 7 and 8 of the NES must still be used to determine whether any application should be granted. [R, C] Policy 15.1.14 – Except as provided for by Policy 15.1.15, apply a zone of reasonable mixing to the receiving waters for all point source discharges to water. The zone shall not exceed (as measured from the discharge point): (a) For rivers and streams, the lesser of: (i) a distance downstream equal to seven times the width of the river (allowing for low flows); or (ii) 200 metres downstream. (b) For rivers subject to tidal influence at the point of discharge: (i) as for rivers in 15.1.14(a), plus a distance upstream equal to half of that allowed downstream. (c) For lakes and wetlands (with open standing water): (i) within a radius of 100 metres of the discharge point. 15 – 16