More than a dozen volunteers organised by the Mt Barker Residents’ Association cleared rubbish from several kilometres of the river between State Highway 6 and a point beyond the Ballantyne Rd bridge.
In two hours they picked up 1.14 tonnes of rubbish.
Secretary Chrissie Thomson said it was "so sad" some people regarded the area as a tip.
"We found household rubbish, three cars, parts of a dead horse, a lamb, part of a pig, parts of deer, dead fish in bags, chilly bins of old food, clothing, old furniture, drums, tyres, bits of metal, iron, books, bottles, camping gear, you name it."
The area is next to the Wastebusters recycling centre and the district council’s waste transfer station.
Wanaka Community Board member Ed Taylor described the rubbish dumping as "Wanaka’s dirty little secret".
"This is not the first time locals have finally had enough and done a clean-up
... I think the time has come to look at some restrictions on access to this area."
Mr Taylor suggested a fence to keep vehicles out but allowing people to use the area for walking, exercising their dogs and riding their horses.
He would be raising the issue at a community board meeting.
Board chairman Barry Bruce believed the solution might be to impose heavy fines on offenders.
