The volunteers removed 867 kg of trash from the Lavant River, including 281 cans, 227 plastic bottles, 95 glass bottles, three shopping trolleys, a paddling pool, 20 shotgun cartridges and a garden sofa.
The team is focusing on areas around Westhampnett Road, Barnfield Drive and south of the A27 near Apuldram.
The clean-up was organized by the Final Straw Foundation and the Western Sussex Rivers Trust, with support from the South Downs National Park Authority and Chichester District Council, to restore habitats and improve water quality.
The drought is putting pressure on rivers across the region.
A “severe” drought has been declared in Sussex after the county recently experienced some of its driest weather on record.
The declaration covered parts of East and West Sussex, as well as areas of Cornwall, Devon, Dorset and Somerset.
Helen Littlejohn of the Final Straw Foundation said: “This summer’s heat waves have highlighted how important our rivers and water quality are, not only for our wildlife but also for our health.
“Water is such a hot topic at the moment, and we all have a responsibility towards our water quality.
“Plastic waste that we see does not go away, but breaks down into smaller and smaller pieces, threatening all the wildlife that depends on this ecosystem, eventually ending up in our food chain and inside us.
“It is estimated that we eat 5 grams of plastic per week, equivalent to the weight of a credit card! By removing plastic waste from rivers, this will reduce PFAS pollution in our waterways and help improve our health.”
Last week, an MP called for stronger environmental protection for a rare chalk stream.
Jess Brown-Fuller, Chichester’s MP, urged the Environment Agency to introduce a phosphate limit for the River Lavant following a recent visit to the river where she met with volunteer citizen scientists and staff from the Western Sussex Rivers Trust.
Ms Brown-Fuller said: “It was incredibly valuable to return to the River Lavant to hear directly from citizen scientists about the work that goes into monitoring their health.
“The Lavant River is a precious chalk stream found almost nowhere else in the world, and it deserves much better protection than it currently receives.
“I will continue to support the Trust’s work and push the Environment Agency to introduce a proper phosphate limit for this stretch of the river.”
Phosphate pollution in the river has been linked to effluents from sewage treatment works.
The trust is seeking a review of the Environment Agency permit, which could lead to a phosphate limit on the treatment works.
Following her visit, Ms Brown-Fuller tabled a parliamentary motion highlighting the global importance of chalk streams and calling for achievable phosphate reduction targets.