Devon County Council is urging people to treat recycling centre staff "with respect" following reports that workers were verbally abused and threatened over the weekend.
It follows unprecedented demand at the local authority's Household Waste Recycling Centres, in part due to the recent good weather.
To enable social distancing, the number of offloading spaces in each site is still limited.
This led to delays and long queues, which the council believes contributed to multiple incidents of aggressive and abusive behaviour towards staff.
The council has also warned the public that sites could be closed temporarily if queues start causing a safety hazard on the public highway, and people may be asked to come back later.
Sites may also have to limit the number of vehicles that can join queues towards the end of the day, to enable those already waiting to be served before the centre closes.
To help stop traffic people are being asked to delay disposing of waste for a week, and to use Kerbside waste collections if they only have small amounts of waste or recyclables.
Councillor Andrea Davis, DCCs Cabinet Member for Infrastructure, Development and Waste said: “The queues are the combination of nice weather leading to extra demand and social distancing measures which have reduced our capacity.
“I understand people are frustrated, but it doesn’t justify aggressive and abusive behaviour towards site staff who are just trying to do their jobs and keep everyone safe.
“If you must use our recycling facilities during lockdown, please be patient. Site staff are critical workers who have been working tirelessly throughout the pandemic so please, they deserve courtesy and respect. Be nice.”