Stormwater
Stormwater is rainfall which falls onto all surfaces, absorbent and hard, and is diverted from streets and roads via a series of underground pipes. This water is released into our wetlands and rivers, including the Torrens and Sturt Rivers , and eventually discharged out into the sea. If pollutants such as oils, detergents and litter, get into stormwater drains, they flow untreated into our streams, waterways and coastal waters. These pollutants can damage the environment by hurting plant and animal life and affecting freshwater and coastal ecosystems.
REMEMBER: unlike wastewater, stormwater is NOT treated before it enters our waterways
Stormwater drain in Largs North dunes
Did you know there are over 100 stormwater outlets between Marino Rocks and Outer Harbour ? The Torrens , Patawalonga and Port Rivers also discharge stormwater into the sea.
How does stormwater pollution affect the coastal environment and creatures that live there?
- Sediment (e.g. sand, silt and soil) in the water reduces light penetration and affects photosynthesis, the process that allows seagrass meadows and seaweeds to use light as their source of energy to grow. Heavy sediment loads also impact on tiny animals living on the bottom of the ocean and fish, by smothering their habitats or clogging their gills.
- Stormwater often contains high amounts of nutrients (mainly in the form of phosphorus, nitrogen and ammonium). These nutrients come from fertilisers, detergents and other household and industrial chemicals. The result of such an increase in nutrients is called eutrophication, which causes red tides, yellow and green slimes and slicks - all of which encourage the growth of tiny animals and plants. These microscopic organisms can cover or break the seagrass leaves, often resulting in smaller, less healthy meadows.
- Nutrients often trigger the growth of sea lettuce (Ulva), a type of algae that grows in thick mats, smothering seagrass meadows and the aerial roots of mangrove forests.
Sea lettuce at Barker Inlet
- Large amounts of unsightly litter from stormwater, which does not get trapped by trash racks, can end up in the sea endangering our marine life. Imagine what a plastic bag can do to a seal or dolphin, or what damage a cigarette butt can do to the stomach of a turtle.
- Heavy metals (eg. mercury and lead) from stormwater accumulate in the tissues of fish and crustaceans and can poison humans and animals.