Approximately 80% of plastic pollution in our ocean comes from land-based sources, with the vast majority flowing through drains to our waterways and oceans via stormwater runoff. Urban stormwater runoff often also contains harmful levels of other less visible (but extremely damaging) pollutants, such as microplastics, suspended solids, heavy metals, nutrients and bacteria. Stormwater is recognised as the key source of pollution in our urban waterways and the vast majority of marine debris entering Australian waters is land-based and generated locally.
The impact of stormwater runoff within Australia is due to a combination of factors: (i) high pollution generation rates in urban areas; (ii) the vast majority of urban areas have no stormwater treatment systems; (iii) where stormwater treatment systems are integrated, these assets receive minimal (and often zero) maintenance (e.g. to remove accumulated material).
To mitigate the impact of stormwater runoff within Australian waterways (and the ocean), a range of actions are recommended, including (i) ban on single use plastics, supported by appropriate education; (ii) increased and prioritised distribution of stormwater treatment systems (for ‘high litter generating areas’); (iii) mandatory requirements for the appropriate maintenance of stormwater quality assets.