Environment Waikato has responsibility under the RMA for managing the water in the CMA. Water quality can be affected by the adverse effects associated with the discharge of contaminants resulting from activities within and adjacent to the CMA.1
Discharges into the CMA have three main sources - point source discharges, non-point (or diffuse) source discharges, and discharges from river systems. Point source discharges are those discharges that discharge through a pipe or a recognisable or definitive point. Non-point source discharges and river discharges require integrated management of both water and land-based activities undertaken above Mean High Water Springs
The level of effects from discharges is dependent on such factors as the nature, scale and location of the discharge, and the nature of the receiving waters. When considering any use of water in the CMA, aspects of water quality which need to be considered include, for example, water clarity and colour, temperature, dissolved oxygen, biological growth, nutrient levels and currents, as well as recreational, cultural and amenity values.
The taking and use of coastal water is unlikely to have any adverse effects on the CMA if the take rate and quantity are managed. Sea water may be used for cooling purposes, desalination, ballast, cleaning of ship structures, aquaculture, and so on.
Damming or diverting water, either in the CMA or in streams or rivers running into the CMA, can change current patterns and sedimentation, affect water temperatures and aesthetic and ecological values.
In addition to wind and wave action, sedimentation arises from activities in the CMA which disturb the foreshore or seabed, as well as from land-based activities or from. streams and rivers. Sedimentation can affect various characteristics of the CMA, including water clarity, estuarine and sediment current patterns and the diversity, distribution and abundance of flora and fauna.