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  Environment » Natural Resources » Water » Stormwater pollution

Stormwater pollution

Photograph of coastal stormwater drain outletWhen pollutants get into stormwater drains they can flow untreated into our rivers, lakes and coastal waters, potentially harming plant and animal life and people's health. 

What causes stormwater pollution?

Stormwater drains are designed to carry clean rainwater into our waterways.  Have a look around: there'll probably be drains right outside your front gate, in your own back yard or on your farm.

These drains are not a dumping ground for waste liquids and materials. But pollutants get into our streams and coastal water because people allow waste, contaminated water and rubbish to get into them. 

Many normal everyday activities can pollute stormwater, if any related waste or dirty water gets into the drains.  Washing your car or paint brushes, washing down spilt chemicals or  letting livestock wander through drains. You need to remember that stormwater and wastewater systems are quite different:

  • Stormwater goes directly into waterways.
  • Wastewater is treated before it reaches waterways.

Effects of stormwater pollution

People can get sick. Plant and animal life can get sick and die. Our beaches and waterways become dirty and degraded.

  • Drinking water can become contaminated.
  • Food sources such as shellfish, eels, koura, watercress and fish can become contaminated.
  • Bacteria and toxins can enter your body through water activities, such as swimming, especially just after rain.
  • Toxic substances, such as vehicle wastes, pesticides and paint, poison streams and waterways. 
  • Plant material, sewage, and some chemicals starve water of oxygen, choking aquatic and marine life.
  • Large amounts of rubbish from stormwater ends up in waterways and on our beaches. It looks ugly, and it's bad for the environment.
  • Heavy metals from stormwater build up in the tissue of fish and seafood and cause poisoning.
  • Bacteria and viruses from untreated human and animal wastes are allowed to drain into natural waterways, making them unsafe for swimming and drinking.
  • Sediments from waterblasting, concreting, and earthworking operations affect water clarity.

Waikato Regional Council helps prevent and manage stormwater discharges

  • We have provisions and rules for stormwater discharges. Check out our policies and plans, especially our Regional Policy Statement, Waikato Regional Plan and Regional Coastal Plan.  
  • We regularly monitor the water quality of our region's waterways and coastal areas. This helps us  with policy making and resource consent decisions.
  • We regulate and monitor activities that impact on our rivers, lakes and coastal marine areas.
  • We provide advice and support for efforts to reduce the impacts of farming on waterways through fencing and planting waterway margins. 
  • We support and advocate practices that try to reduce and prevent contaminated water run off.
  • We prohibit stock from accessing high priority waterbodies and coastal marine areas.
  • We support care groups. Their riparian management work, such as planting and fencing helps decrease sediment and nutrient runoff to estuaries and the coast via streams and rivers.
  • We support environmental education school programmes throughout the region.

Managing your stormwater - what you can do

Only clean rainwater should enter our stormwater drains. Don’t be afraid to ask for advice if you’re not sure about what you should be doing to stop pollution getting into them.

On the work site

Around the home

  • Make sure that any contaminated water from your property doesn’t enter the stormwater drains.
  • Wash your car and boat on the lawn so that the soapy water and dirt doesn’t enter the stormwater drains, and wash your water-based paintbrush at an inside sink or on the lawn or garden.
  • Clean up any spills or dirt around the home by soaking up the mess or sweeping it. Don’t just wash it down the stormwater drain.
  • Don’t hose housewashing, concrete cleaning or any other chemicals down the stormwater drain.

Around the farm

  • Install proper holding ponds for farm animal wastes.
  • Fence off streams from cattle.

Other suggestions

  • Store your chemicals in a safe place.
  • Don’t tip unwanted paint, oil or any other substance down the stormwater drain. Dispose of them responsibly. 



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