5. Allocation of Public Resources Volume One depending on the rate of groundwater pumping, the distance between the point of abstraction and the river and the ability of water to move through the sediments on the river bed and through the adjoining soils. Where groundwater abstraction causes stream depletion effects, there is the ability for the same effects identified in Issue 5B to be created, either in isolation or in combination with other groundwater and/or surface water takes. [R] Objective 5.6 – Ensure that the taking of groundwater does not cause significant adverse effects on river flow. Natural and human use values supported by rivers are flow dependent. Any reductions in river flow caused by groundwater abstraction at times of low flow have the ability to adversely affect the natural and human use values supported by the river. As for direct takes of surface water, the objective with respect to groundwater takes that have stream depletion effects is to maintain the natural and human use values supported by flow in the river. [R] Policy 5.6.1 – Unless there is an identified aquifer dominant Freshwater Management Unit, all water within a catchment will be managed as a surface water resource. This means that the minimum flow, management flow and allocation limit established for the river dominant Freshwater Management Unit will also apply to groundwater takes. In a Marlborough context, an aquifer is a significant body of water stored in the unconsolidated materials below the ground surface. The groundwater occupies the pore space between sand, silt or gravel particles. In many cases, the groundwater associated with rivers does not involve the storage of a significant volume of water and the groundwater is therefore not recognised as an aquifer. In these circumstances, the taking of groundwater has greater potential for stream depletion effects. This policy directs that the potential adverse effects of groundwater takes will be managed in the same manner as surface water takes. The effect of the policy is two-fold: • any take of groundwater will be included within the allocation provided from the river; and • the environmental flow set for the river will apply to any groundwater take. Aquifers are excluded from the policy as either the volume of stored groundwater has the potential to buffer the effects of groundwater abstraction on flows in rivers or there is sufficient physical separation between a river and underlying aquifer so that no stream depletion effect is caused. [R] Policy 5.6.2 – Manage the potential for groundwater takes in proximity to spring-fed streams on the Wairau Plain to cause a recession of the position of headwaters of the streams by establishing aquifer minimums below which the taking of groundwater must cease. As the slope of the Wairau Plain flattens, groundwater returns to the surface in the form of springs. The largest of these spring systems are Spring Creek, Fultons Creek and Murphys Creek. Although not retaining outstanding natural character, these rivers are still highly valued by the community for the clear water that flows in them and in the case of Fultons Creek and Murphys Creek, the provision of a baseflow of water to sustain the Taylor River during the summer months. The taking of groundwater in close proximity to spring-fed streams has the potential to cause stream depletion effects. The greatest risk is that abstraction could cause a downstream shift in the position of the headwaters. In order to preserve the remaining natural character of these spring-fed streams and to maintain the amenity values that they support, this policy identifies that groundwater takes close to spring-fed streams will be subject to specific management. 5 – 22