What is stormwater?
Stormwater is rain that runs off our houses, footpaths, roads and carparks. It runs into gutters and drains that flow into the stormwater system.
Where does stormwater end up?
Stormwater collected in the stormwater system is discharged directly into Timaru’s streams, rivers and the sea.
What is the difference between stormwater and other kinds of water?
When talking about water, some common terms that are used are
- surface water
Surface water is what we see in our rivers, lakes, streams, wetlands and estuaries.
Groundwater is the water that exists in aquifers beneath the ground. This is replenished by rainwater that travels through the soil.
Wastewater is the water that goes down drains from inside our house, after we do our washing, or flush the toilet or have a bath.
Stormwater doesn’t go into the sewers. It runs through a separate piped system from that of wastewater or across the ground.
Why is it important to manage stormwater well?
Stormwater is discharged, untreated, into streams and Rivers so it's important that it is as clean as possible. If contaminated stormwater pollutes the river and streams, this can have a negative effect on aquatic life, the natural environment and public health. It can also limit recreational use of the river.
Contaminants such as debris, fats and oils can build up in the stormwater system causing blockages that may damage the system and cause flooding.
What are our responsibilities in regards to stormwater?
We all have an important role to play in protecting the stormwater system. The public is responsible for ensuring contaminants, like paint, chemicals and fat and oil don't enter the stormwater system. Landowners are responsible for managing the stormwater runoff from their land to avoid polluting our waterways.
Timaru District Council is responsible for managing the discharge of stormwater from our public stormwater systems into the Streams and River. Environment Canterbury is responsible for ensuring our fresh water ecosystems are protected. They do this through setting Regional Plan rules and issuing resource consents that control discharge of contaminants into water (as well as onto or into land and air).
What do I do about a stormwater run-off from my neighbour's property flooding my property?
It is a fact that stormwater flows from other properties naturally, either via an overland flow path or via a stream (from high ground to lower lying ground). It is your responsibility to manage stormwater falling and flowing naturally on your site.
If you have an issue with any of the following, you should first speak to your neighbour:
- Water flow problems caused by natural ground seepage on private property
- Diverting or blocking the natural flow of water from landscaping, fences and walls or a small trench
- Pool overflows caused by excessive rainfall
Activities like raising the ground level, increasing your impermeable area or blocking a flow path can increase the amount of stormwater flowing to your neighbours site. You will need to stop the activity or cause or you can use a system to prevent the extra stormwater from flowing across your boundary.
Council recommends you talk to your neighbours about any flooding problems you may be experiencing. In many cases, a resolution can be reached that will satisfy everyone’s needs. You may need to consult legal advice, so that any agreement you made with your neighbour is legally enforceable and appropriate for future owners of the land should it be sold on.
Local councils are responsible for controlling new buildings and the effects of land use to reduce flood risk. They can put special controls on buildings to make the buildings safer from flooding. Councils can also set rules about where buildings can be located, where subdivision can take place, and the effects of land use. In a large flood, councils will coordinate with the emergency services and utility providers to minimise the impact of the flood on people and properties.
Environment Council manage rivers and catchments. They also control land-use activities through the Resource Management Act, as well as regulate large dams under the Building Act.
Where can I find information about Stormwater and flooding on a property?
When you buy a property or build a house or business, you can ask about local flooding issues. If you are building, you can site your home out of any floodable areas, raise the habitable floor levels or make your house using materials better able to withstand floods.
What is the Council doing to encourage good stormwater management?
The Council provides guidance on what can and can't enter the stormwater system and offers practical stormwater solutions through its education programme.
What issues do we need to manage?
There are a number of stormwater issues to manage. They include:
- Hazardous substances such as oil and chemicals being discharged into waterways and affecting ecosystems.
- Wastewater entering the stormwater system through illegal connections which then get into waterways where people swim.
- Stormwater getting into the wastewater network which overflows into waterways and onto land in heavy rainfall.
- Uncontrolled sediment entering the stormwater network. This can build up in parts of the network which affects the capacity of the system.
- Damage to pipes and modifications to established overland flow paths which can increase risk of flooding.
Other resources and reading materials
- Flood protection & Drainage bylaw (Environment Canterbury)
- Drain maintenance (Environment Canterbury)
Last updated: 09 Mar 2022