Bin collections on Anglesey could be hit by industrial action over pay as a union decides to ballot its members.
The Unite union claimed workers were underpaid with many earning the £7.83 statutory minimum wage despite Anglesey topping the Welsh recycling table.
The council has decided to offer its staff the "living" wage of £9, but as refuse workers are employed by Biffa they are not automatically entitled.
Anglesey council said it was a matter for Biffa, contracted until 2021.
The living wage is a figure promoted by campaigners who claim it more accurately reflects the cost of living, which they say has been voluntarily adopted by more than 4,700 UK employers.
Paddy McNaught, regional organiser for Unite, said: "Despite offering a second-to-none service, which is reflected in Anglesey's recycling rate, this is not reflected in the level of pay.
"Both Biffa and Anglesey Council need to come up with an improved offer, with all calls for negotiation having fallen on deaf ears," he told the Local Democracy Reporting Service.
"While most of the lowest-paid council staff will benefit from being paid the living wage, as things stand this will not apply to refuse staff despite living on the island and paying council tax like everyone else."
Anglesey council, which spent £3.8m on waste collection in 2017-18, is hiring a new £48,000 "waste czar" to look at ways of saving money on the service when the current contract with Biffa ends.
The officer will be expected to either find another firm to do the work or make moves towards having the council run the service itself.
A spokesperson for the council said: "We are aware of ongoing talks between our waste management contractor, Biffa, its employees and their trade union representatives.
"This is currently a matter for Biffa and, as such, we would not wish to comment further at present."
Biffa has also been asked to comment.