Water resources and wood processing

How do wood processing activities potentially influence water flows?

Sawmills take water for wood processing in the sawmill, including for cooling saw blades and in the process of preserving wood.

Pulp and paper mills require large quantities of water in their production systems, although some have programmes to actively reduce water use. Closed-cycle pulp and paper mills are now built to dramatically reduce the amount of water used and eliminate discharge of almost all wastewater. Examples exist in Australia and the USA but not in New Zealand at present.

Impacts of water take (abstraction) on water quality and mahinga kai

• Changes in flow - changes in water levels and flow variability alters available mahinga kai habitat and the invertebrates they feed on.
• Reduction in habitat - a decrease in water levels reduces habitat for fish and can impact feeding and spawning success.
• Reduction in specialist habitats - a decrease in water level reduces flow to riparian wetlands, backwaters, and intermittent streams.
• Decreases in species abundance and diversity - aquatic species have developed life history strategies in direct response to natural flows; for example, diadromous fish species migrate up and down the river at various times of the year and rely on preferred velocities and depths.
• Changes in sediment accumulation - flow reduction affects movement and deposition of sediments in streams and rivers.
• Changes in water quality parameters - for example, turbidity and temperature levels can increase with reduced flows in rivers.
• Increases in algae accumulation - algae respond to changes in temperature and nutrients, which are likely to increase with reduction of flow, especially during summer months.

Learn more about the potential environmental impacts of instream barriers