A Victorian first, the Let’s Strain the Drains project targeted upstream sources of pollutants by installing and monitoring 120 at-source litter traps in the stormwater infrastructure of six metropolitan councils around Port Phillip Bay. Being a significant transport pathway for pollutants, stormwater is a key piece of the marine debris puzzle as it acts as an outflow point for litter in urban runoff. Monitoring work took place from November 2019 to May 2020 and involved six community audit events where 94 volunteers helped to sort and count all captured litter items for inclusion in the Australian Marine Debris Initiative Database.
In order to obtain land-use relevant data and compare evenly across multiple Councils, five traps were placed in each of four different land-use types selected on the basis that they typically generate the highest concentrations of litter:
- Central Business Districts (CBDs)
- Industrial Precincts
- Shopping Centres
- Public Transport Terminals
In total, each Council had 20 traps within their local government area, making for a total of 120 traps distributed around Port Phillip Bay.
During the project period, a total of 75,931 macro-litter items and 677,114 micro-litter items were captured with the top two macro-litter items being cigarette butts and miscellaneous paper. Hard & soft plastics were the dominant material category found across all sites and were noticeably highest in CBD sites.
Rounds five and six occurred during the COVID-19 restrictions, with data showing up to a 75% decrease in litter compared to the highest litter round in December 2019.
This unique dataset provides valuable insights that can be used at both local and state government levels to inform strategic plans that tackle litter at the source and prevent further pollution around Port Phillip Bay beaches and waterways.
The full report is available on our website here.
Let’s Strain the Drains project was funded by the Victorian State Government and delivered by Tangaroa Blue Foundation, Cleanwater Group and Sustainability Victoria with support from the Cities of Wyndham, Hobsons Bay, Moreland, Kingston, Maribyrnong, and Greater Dandenong, and data analysis support from the University of NSW.