Land transport activities can adversely affect water quantity and quality through discharges by:

  • affecting natural waterways and drainage patterns
  • increasing local stream flood flows
  • transferring pollutants from road surfaces
  • erosion and sediment from construction and maintenance activities entering watercourses.

This can have significant impacts on waterways, resulting in a deterioration and destruction of flora and fauna biodiversity, aesthetic features, structures and water quality.

Land transport systems also add to local and wider flooding issues, which we need to manage through drainage systems (piping, culverts, swale, ponds, wetlands, table drains, etc).

We need to proactively manage our activities to ensure we minimise adverse effects on the receiving environment.

We do this through our standards and guidance, which ensure careful planning and design to avoid, remedy or mitigate effects of excess flooding, erosion, sediment runoff and contaminated stormwater runoff. These all align with our responsibilities set through regional councils.

Our policy

Our policy on water resources and erosion and sediment control can be found in:

Standards and specifications 


* Note: our Fish passage guidance for state highways is currently out of date. We are in the process of updating it, along with a new policy and specification. In the meantime, refer to and follow:

Resources and tools


Further information

For further information contact