Members of the local community reported concerns about plastic pollution to the Environment Agency last week.
The Agency responded by mobilising one of its Field Teams which spent two days removing blockages near the river's bridges and along its banks.
The build-up of discarded plastic bottles and other waste was spotted by a keen walker earlier this month.
The man, who asked not to be named, said he had counted hundreds of plastic bottles washed up along the banks of the river since the beginning of October.
One of the blighted spots is at a footbridge over the River Darwen at Winery Lane, behind the Capitol Centre, where it meets the River Ribble.
Pictures taken near the retail park show plastic waste and other detritus tangled in dead tree branches and driftwood.
"It's got worse and worse over the past couple of weeks", said the concerned 29-year-old.
"It’s frustrating because it's obviously coming from somewhere close by, because the River Darwen is a relatively short river.
"I've reported it to the Council and the Environment Agency, but there doesn't seem a rush to do anything about it.
"I'm just going round in circles with them. Nobody seems to want to take responsibility for it.
"It's such a shame because it's a lovely route to walk along the river towards the Capitol Centre, even in winter.
"It's an escape from all the traffic and industry around this part of Preston, but now it seems you can't even avoid pollution when you take the scenic route."
The Environment Agency said the blockages have now been cleared and a quantity of waste has been recovered from the river and its environs.
An Environment Agency spokesperson said: "We were made aware of reports of a blockage on the River Darwen at Walton-le-Dale last week.
"Our Field Team went on site to investigate and determined the cause to be the result of two large trees which had washed downstream.
"Our team worked on site for two days and we can confirm that the blockage is now clear.
"Our thanks go to the member of the public who reported the incident to us and to our partners at United Utilities who rearranged their tanker deliveries so that we had a clear path in which to work."