Residents living between Mandurah and Rockingham who were plagued by a foul odour coming from two businesses in Nambeelup say the stench is back.
Earlier this year, the Department of Water and Environmental Regulation (DWER) received over a thousand odour complaints from locals.
An investigation in February found the smell was coming from C-Wise, a liquid waste and compost manufacturing facility and CM Farms, a piggery.
In March, both businesses were issued with Environmental Protection Notices which ordered them to rectify the odour issues.
Reports of the smell decreased over winter and spring but now residents say the awful stench is back.
Wendy Munroe has started a private Facebook group called Lakelands and Surrounds Stink which now has over 400 members.
She said residents have had enough of the smell.
"It's a putrid stench, it is something that lingers, if you put washing out it goes through your washing, you can't have your airconditioning on because it goes through your airconditioning...it's really sad, you can't enjoy this glorious lifestyle that we have here because of the pong," she said.
"I can't believe that it's not an unhealthy situation, we're smelling faecal matter, animal urine, blood and bone, I just can't believe that it can't be injurious to your health.
"We want to enjoy our beachside lifestyle and you can't.
"You can't go have a barbeque when that stench is out, it's beyond putrid, it's ungodly, it's like living in a corpse or your head's stuck up a poor animals backside."
A DWER spokesperson said they acknowledge the impacts the odour is having on the community and are taking the issue "very seriously".
In an update on the DWER website, the department said C-Wise are conducting maintenance for two weeks starting from December 9 which will temporarily increase the smell.
"C-Wise will begin maintenance work to remove sludge from two of their operational ponds in a carefully controlled manner," the update said.
"While this process may temporarily increase the risk of odour emissions from the site, it will provide improved operating standards for the future.
"This is maintenance work that has been reviewed and accepted by the department and is required by their licence."
The department said mitigating odour issues can take some time to fully address.
"The department is determining whether further regulatory actions are required to mitigate odour emissions from the Nambeelup premises and to resolve odour issues in the area," the department said in an update.
"The department is grateful for the community reporting the ongoing odour impacts which greatly assists in the investigation and identification of odour sources."
Members of the public are advised to report any odours at the time the smell is occurring by calling the Pollution Watch Hotline on 1300 784 782 or using the online reporting tool.