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Changing Water Flow / Quality

Advice on minimising potential negative impacts of any activity changing the flow or quality of water in an area, from the creation or drainage of dams, to land drainage or irrigation, to activities leading to increased sediment in nearby water bodies

What do we mean?

Activities which affect rivers and streams, run-off, water table levels and other aspects of a site's hydrology may have an impact on threatened species. Activities which can affect water and water quality include: drainage works, building dams and weirs, bridges and culverts, irrigation and extraction of water, removal of vegetation (through cutting or burning), planting non-native vegetation (including eucalypts), the use of pesticides and herbicides near waterways, acidification, salinisation of soils, nutrient enrichment from farmland and suburban areas, and increased sediment input into waterways from earthworks and subdivisions.

General points to consider

  • Many threatened species depend on the presence of water in their habitat.
  • Many of these species are highly sensitive to small changes in water flow at particular times of year, as well as to changes in water quality including levels of chemicals and sediment in the water.
  • Changes to hydrological conditions through activities such as dam construction, irrigation activities, drainage works and water extraction can occur far beyond the area of the activity, thus exerting far-reaching impacts on threatened fauna and their habitat.
  • Always consider the potential effects of runoff and seepage when using chemicals or disturbing soil.
  • The effects of stormwater can extend well beyond the discharge point of the water.
  • To avoid spreading water-borne weeds and diseases it is important to follow good hygiene and washdown procedures. See also NRE Keeping it Clean manual for useful advice on avoiding the spread of freshwater pests and pathogens.
  • See the NRE Guidelines for Safe and Effective Herbicide Use Near Water for more information on using chemicals near waterways.


The agencies most commonly responsible for regulating this activity are listed below (but refer also to the Permits section on the Planning Ahead page):