13. Use of the Coastal Environment Volume One [C] Policy 13.13.5 – Enable opening of the Wairau River and Wairau Diversion mouths where this will assist to reduce the effects of flooding, improve land drainage and enable navigation across the river mouths. The Wairau River mouth bar is a natural feature that has a dominating effect on water levels in the Wairau estuary and lagoons, the lower Wairau (to upstream of Ferry bridge) and the lower Ōpaoa. If the bar is partially closed, the water therein may stay almost completely devoid of saline water, or conversely, stay with an extensive saline wedge. Either situation could adversely affect ecological values in the area. Opening of the Wairau River mouth will therefore improve water movement, mitigate flood risk and ensure that navigation across the river mouth can occur. It is appropriate to provide for the opening of the Wairau River and Wairau Diversion mouths to address these issues, subject to meeting standards. [C] Policy 13.13.6 – Enable the clearing, cutting or realignment of stream and river mouths, drainage channels and stormwater outfalls and pipes within the coastal marine area to protect public health and property during flood events. The blockage of stream and river mouths, drainage channels and stormwater outfalls and pipes through deposition of sediment or debris can result in flooding of adjacent land or impoundment of water, which could pose potential health risks. It is necessary that appropriate provision is made for work to be undertaken to address these situations. [C] Policy 13.13.7 – Proposals for an activity involving disturbance of the foreshore or seabed not otherwise provided for shall demonstrate that: (a) there will only be short-term adverse effects on plants, animals or their habitat and the area will be naturally recolonised by a similar community type; (b) the disturbance will be undertaken in a way that: (i) does not result in any significant increase in water turbidity or elevated levels of contaminants; (ii) does not result in significant adverse changes to bathymetry, foreshore contours, sediment particle size or physical coastal processes; (iii) does not have any off-site adverse effects; and (iv) is unlikely to cause or exacerbate shoreline instability or coastal erosion on adjacent coastal land. There will be instances where an activity involving some form of disturbance to the foreshore or seabed has not been otherwise described or provided for in the previous policies. Where this is the case, this policy will assist in determining the outcome of any resource consent application, having regard to the values of the coastal environment. For a number of those values, it will be appropriate to have regard to other policies of this chapter and others of the MEP. Additionally, where a disturbance activity has been provided for in policies under Objective 13.13 but does not meet permitted activity standards, the matters in this policy must be considered by decision makers. [C] Policy 13.13.8 – Where the removal of sand, shingle, shell or other natural material from any foreshore or seabed is proposed, the matters in Policy 13.13.7 shall apply. Historically, the extraction of sand, shingle, shell or other natural material has not occurred to any significant degree within Marlborough’s coastal marine area. However, proposals may be made to undertake such activities and it is therefore appropriate to provide policy guidance here, as the effects of such activities would be similar to those for other disturbance activities. 13 – 38