Nearly 140 volunteers have spent thousands of hours clearing debris from the river, preventing the blockages which were a major factor in the 2007 floods which ravaged the city.
Under the guidance of the River Stewardship Company (RSC), a social enterprise working to improve and protect Sheffield's waterways, they have removed mountains of waste, from fridge-freezers and old machine parts to traffic cones and tree trunks.
They have also cut back invasive species along the banks and kept other vegetation under control so it does not clutter the river, blocking the flow during heavy downpours.
Keeping the river clear is a key plank of the work to protect businesses along the Lower Don Valley, an eight-mile stretch of river from Nursery Street in the city centre to Blackburn Brook at Meadowhall.
A £19 million programme to build new flood walls, repair and raise existing ones and create other defences like dams and flood gates along that stretch is on course for completion this autumn.
But keeping the river clear is a task which must continue long after those defences are in place, explains Hellen Hornby, community team manager at the RSC.
"The river is looking a lot nicer and better maintained than it did when I started in 2010, and a lot of that's down to our volunteers," she said.
"We've removed all sorts of things from the river which could cause blockages, including tyres, sofas, warehouse doors and trees, and it's much clearer now.
"Because nobody had really been looking after it, one of the problems we had was that the crack willows had been allowed to grow until they became huge and cracked and fell into the river.
"If we were to stop today, these tiny things you see in front of you, give them a bit of time and they would be massive. Prevention is better than the cure.
The RSC runs regular clean-up sessions for volunteers, and today (Tuesday, June 20) I meet a bunch in action near the pocket park on Nursery Street, near the Wicker, which forms part of the flood defence measures.
They clamber down a ladder to the riverside, where they hack away heaps of Himalayan balsam, an invasive species which left unchecked could severely harm the ecosystem and damage flood defences.
A traffic cone is the most interesting item found today, but last year one volunteer found a live rifle grenade in Attercliffe, in 2015 a woman's body was sadly pulled from the water near the same spot and earlier this month a bag of cannabis was discovered at a known haven for drug-users.
Today's volunteers include a mixture of environmental science graduates and undergraduates, keen to get valuable experience while making a difference, and retired workers who want to help Sheffield's flora and fauna flourish.
Paul Winks, from Hillsborough, has been volunteering for four years since retiring from his job as a BT engineer.
His house was not affected by the 2007 floods but he remembers encountering floodwater four feet deep on Penistone Road on his commute home. He also recalls being kept busy at work over the following weeks and months repairing and replacing damaged equipment.
Although he remains frustrated by the amount of fly-tipping, he says it is satisfying to see more people enjoying the riverside now it is looking smarter.
"If it's possible to say something good came out of the floods, I think it's that people are more aware of the river and take more care of it," adds the 64-year-old.
* For more information about volunteering with the RSC, email [email protected] or call 0114 3540 012.
WEATHER WARNING: Torrential thundery downpours to lash SheffieldLet there be light on £20m Sheffield Boeing factory planWe'd vote to REMAIN if Brexit vote was held again, say majority of Star readersVandals hunted over blaze at Sheffield cricket groundSheffield council issues warning about cold callers offering to resurface drivesEmergency services praised for 'ordering fish and chips' for Sheffield school kids involved in bus crashMan threatened his ex with a knife during a rowSheffield Wednesday's 2017/18 fixtures: Everything you need to know ahead of tomorrow's releaseSheffield United Column: Why Chris Wilder deserves a new Bramall Lane contractDownload The Star's mobile app now for FREE