The rubbish was dumped close to the Bridge and Oroarkes Rds pedestrian bridge in Fernside.
ECan flood protection recovery manager Shaun McCracken said illegal dumping of green waste and inorganic items is rife across the region, putting flood protection, biodiversity, and water health at risk.
"Not only can these items be a health and safety issue for members of the public, animals and those having to remove the rubbish, having these items removed appropriately also comes with a cost to ratepayers."
In many instances, the dumped materials could have been disposed of for free at waste stations, which also offer cheaper disposal rates for green waste than general rubbish.
"If you see suspicious activity or rubbish being dumped in a riverbed, please note the details of the vehicle and location, and report it to our incident reporting line on 0800 765 588 or by using the Snap Send Solve app (for Apple or Android) or online reporting tool," McCracken said.
"It is really disappointing when rubbish is dumped in our riverbeds.
"The ratepayer should not have to bear the cost of this illegal activity.”
By Shelley Topp