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What is Stormwater? Here are some facts to help you understand the causes and effects of stormwater pollution: What is stormwater? Stormwater is all the rainwater that runs off roofs, driveways, footpaths and roads into stormwater drains when it rains. The stormwater drains carry this water into local waterways: creeks, rivers, lakes, bays, harbours and the ocean. What is stormwater pollution? Unfortunately rainwater is not the only thing that ends up in stormwater drains. Stormwater pollution occurs when litter, garden waste, pet droppings, sediment, chemicals, oil and fertilisers get carried along with the rainwater into the stormwater system. Stormwater = rainwater + pollution Unlike sewerage, stormwater is not treated before it goes into our waterways. Stormwater pollution accumulates in creeks, rivers and lakes and has a significant negative impact on the environment. The main components of stormwater pollution are: Organic waste Organic waste, such as lawn clippings, leaves and twigs, uses up valuable oxygen as it decays in water. This deprives fish and aquatic plants of oxygen, and causes them to die. It also covers beneficial aquatic plants (which are often home to fish) and kills them. Sediment Sediment, sand, soil, silt and clay from gardens and building sites make waterways cloudy and reduce light penetration. This affects photosynthesis - the process by which plants convert light into energy - resulting in reduced plant growth. Litter After a downpour, litter (such as wrappers, takeaway food containers, plastic bags, paper, cigarette butts, cans and bottles) can end up in the stormwater system. It contains toxic substances and is mistaken for food by some fish and animals. Durable plastics can wind up in the ocean where they can choke, trap and drown marine animals and birds. For example, turtles commonly mistake plastic bags for the jellyfish they feed on, a mistake that can prove lethal. Plant nutrients Fertilisers contain nitrogen and phosphorous which feed all plants including algae. High levels of nitrogen and phosphorous in waterways can cause algal blooms which can kill fish and aquatic plants. Blue green algae are poisonous to humans and other animals. Detergents may also contain phosphorous, and pet droppings have high plant nutrient levels. Germs Pet droppings and runoff from sewerage or septic tanks contain bacteria, viruses and parasites that can survive in water and are harmful to swimmers. Dirty water clogs fishes' gills and can cause them to suffocate. Sediment also fills up our waterways, which reduces water habitats for birds, fish and animals, and covers beneficial water plants such as sea grasses. Motor and cooking oil Motor oil washed into waterways is harmful to aquatic plant and animal life. Cooking oil clogs drains and is also detrimental to aquatic life. Poisons and chemicals Pesticides, herbicides, paint and other chemicals are toxic to animals, fish and plants. They can disrupt reproduction and kill fish and animals. How stormwater pollution affects humans, plants & animals All living things need clean water to survive. Stormwater pollution makes our creeks, rivers, lakes and ocean unhealthy and unsightly. It reduces water quality and affects natural systems, destroying aquatic life and diminishing the beauty of our waterways. For example:
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