RESIDENTS mistaking Hume's creeks for rubbish tips are sending the waterways down the gurgler.
Litter and waste in the city's waterways has doubled to 500 cubic meters in the year to June, compared with the previous year.
Melbourne Water figures show Hume had the second-highest amount of waterways debris removed in the north-west - equal with Brimbank at 500 cubic metres. Wyndham, with 669 cubic metres, was top of the list.
Hume waterways attracting litter include the Malcolm and Aitken creeks, which run through Craigieburn and enter Merri Creek.
Merri Creek management committee manager Luisa Macmillan said she noticed a lot of litter in Malcolm Creek when she visited three weeks ago.
"I was shocked to see litter, plastic bags and bottles in the creek. Having said that, it's much worse in the inner suburbs. We've noticed a huge increase in the amount of litter in Merri Creek over the past couple of years. Almost every bit of rubbish on the street ends up in the creek."
Melbourne Water west region waterways acting manager Christine Hughes said the large amount of debris in Hume could be due to a growing population and residents disposing of rubbish incorrectly.
"The amount of debris in an area depends on factors including the number of people, pollution and development, the number of waterways and drains that are part of that area and the total size of the area," she said.
"Other factors include large rain events and flooding."
Melbourne Water's Nicolas McGay said: "Everyone can do their bit to help stop rubbish getting into our rivers and creeks by binning their litter when they're out and about, or taking it home with them."
Last year, Melbourne Water provided more than $185,000 to Hume community groups to support projects that improve the health of local rivers and creeks.
The authority also carried out weed control along 93 kilometres of Hume waterways, removing invasive weeds and replacing them with indigenous plants.