Mr Smith said it seemed overall rubbish was down on previous years but the number of needles was up.

"Unfortunately today we've found a lot of syringes," he said.

The scouts group leader said many were found not far from a toilet block with a sharps disposal bin.

"They would only have to walk 100 or 200 yards [90 to 180 metres]," he said.

"But when they have [taken the drugs], they might not be in a position to walk that far."

Mr Smith said his sons, aged 12 and eight, were aware of what to look out for and instructed only to pick up large rubbish.

He encouraged new volunteers to join next year.

"It's a great thing to feel like you've done your bit for the town and it makes the kids feel like they've done their bit and they're involved."

Kathy Spicer said she was volunteering for the first time in many years, "just to help the river system, make it a little bit cleaner".

Picking up rubbish while kayaking on the river was far from a chore, she said.

"I love being on the water, it's beautiful. It's a bit of river medicine."

Dubbo City Council's community participation facilitator, Kathleen Oke, said volunteer numbers were down slightly on last year, possibly because of Saturday's rain.

"It's fairly wet underfoot, so it's a bit of a deterrent," she said.

Ms Oke praised those who turned out every year without fail.

"I'd like to think that one day we won't have to Clean Up Australia Day," she said.

By lunchtime yesterday, 62 Dubbo volunteers had hauled in more than 40 large bags of rubbish.

Last year, more than half a million volunteers across the country removed 16,150 tonnes of rubbish, the organisation estimated.