Volume One 5. Allocation of Public Resources (e) any adverse effects on natural and human use values identified in the Marlborough Environment Plan in the reach of the waterbody to be diverted; (f) any adverse effects on permitted or authorised uses of water; and (g) any adverse effects on the natural character of the waterbody, including but not restricted to flow patterns and channel shape, form and appearance. The matters listed in (e) to (g) are the potential adverse effects created by the diversion of water. The nature, severity and significance of the potential adverse effects are influenced by the matters listed in (a) to (d). The consideration of the matters listed in the policy will allow a determination to be made as to whether the proposed diversion of water is sustainable. Damming of water [R] Policy 5.2.20 – Where water is to be dammed to enable the storage of water, encourage the construction and use of “out-of-river” dams in preference to the construction and use of dams within the beds of perennially or intermittently flowing rivers. The damming of water to store water is a key response to temporary and seasonal shortages of water for irrigation purposes. Stored water provides a reservoir that can be accessed when other supplies are constrained or restricted. The policies and methods under Objective 5.8 focus on the positive effects of storing water. Storage can involve the interception of runoff by damming ephemeral water bodies, the damming of intermittently or permanently flowing water bodies or the placement of abstracted water in purpose-built reservoirs on land. Dams constructed on riverbeds create the potential for a range of adverse effects (see Policies 5.2.21 and 5.2.22 for more detail) that may not be created when water is placed in reservoirs on land. For this reason, the construction of reservoirs on land is preferred to dams within the bed of rivers. However, the policy does not prohibit the construction of dams within the bed of rivers: applications for resource consent can still be made and will be considered having regard to Policies 5.2.21 and 5.2.22. However, district rules will create an incentive to utilise “out-of-river” dams for any water storage proposal. A decision maker may also utilise this policy to consider alternatives to the use of dams within the bed of rivers. The extent to which this consideration is necessary will also rely on the significance of the potential adverse effects of the damming of water as assessed under Policies 5.2.21 and 5.2.22. [R] Policy 5.2.21 – Ensure any new proposal to dam water within the bed of a river provides for: (a) effective passage of fish where the migration of indigenous fish species, trout and salmon already occurs past the proposed dam site; (b) sufficient flow and flow variability downstream of the dam structure to maintain: (i) existing indigenous fish habitats and the habitats of trout and salmon; and (ii) permitted or authorised uses of water; and (iii) flushing flows below the dam; (c) the natural character of any waterbody downstream of the dam structure; and have regard to the matters in (a) to (c) when considering any resource consent application to continue damming water. Where a dam is proposed to be constructed in the bed of a river in spite of Policy 5.2.19, the policy identifies three matters to be provided for as part of the proposal. It recognises that a dam structure can act as a barrier to fish passage, modify the flow pattern downstream of the dam 5 – 9