Stormwater is rain that runs over the ground on its way to the sea. When rain falls on buildings, carparks, roads, driveways and gardens, it flows downhill until it reaches a watercourse (stream, river etc.) or is collected by a pipe system.

Stormwater can cause flooding, erosion and long-term environmental damage.The run-off literally washes the roads of vehicle pollution, animal faeces and litter. The debris ends up in our streams and on our beaches, posing a threat to the marine environment and at times to public health.

In North Shore City we're upgrading our public stormwater systems, building stormwater ponds and installing filters in our drains to improve the quality of stormwater that flows to our streams and beaches. To make a real difference, however, we all need to take responsibility for the stormwater on our own properties.

The council also shares responsibility with the community for natural watercourses and 'secondary flow paths'. These form an integral part of the stormwater system and, although they're not infrastructure assets owned by the council, they need to be managed effectively so they function properly.

Did you know?


North Shore City has:

• 148 km of coastline and 13,000 hectares ofland
• 9,400 hectares served by our stormwater system
• 3,300 hectares of impervious area (e.g. concrete)
• Predominantly clay soil
• An average annual rainfall of 1250 m.
  

The public stormwater system consists of:

• 56 stormwater 'catchments'
• 863 km of pipes
• 18,096 manholes
• 32 detention ponds and tanks
• 27 water quality ponds.