Ways to minimise the effects of diverting water on water quality and mahinga kai.
When natural seasonal flow variations are interrupted by diverting water extreme care must be taken to maintain the amount of water needed to support healthy ecosystems. The amount of water needed is called environmental flow, which considers maximum and minimum flow levels to support a healthy ecosystem. Failure to provide an environmental flow can have serious consequences for water quality and mahinga kai.
The following options can be considered minimum requirements for maintaining natural character and flow when diverting water:
- Identify minimum flows that can be sustained by a waterway.
- Calculate the maximum amount of water that can be diverted from a waterway based on minimum flows.
- Regulate minimum and maximum flow levels in waterways so that there is sufficient habitat for fish and invertebrate life.
- Maintain natural channels and depth - create natural meanders, low flow channels and rest areas for mahinga kai species.
- Prevent temperatures from reaching lethal or extreme levels due to low flow or water levels.
- Facilitate upstream and downstream passage for fish migration where these may be blocked by a diversion - using ramps, ladders, and spillways.
Riparian vegetation - maintaining fish habitat
- Maintain, restore, and enhance riparian vegetation and wetland areas, which serve as spawning grounds and shoaling habitats for mahinga kai. Wetland areas and native planting also create refuge areas, lower water temperature, and provide a food source of invertebrates for mahinga kai species.
- Fence waterways.