BARRIE -- The Holland Marsh is big business for farmers who make their livelihood off the rich, fertile earth, so when cannabis greenhouses moved onto the land, the concerns grew.

"They don't make marshes every day." Farmer David Munshaw is concerned about the future of the marsh. "You can't recreate this. You can't make more marsh soil."

A cannabis operation with its 28 greenhouses has moved in next to Munshaw's carrot and onion farm.

The farmer says marijuana grow ops don't belong in the marsh and covering the land instead of using it is a problem.

"They are taking very productive farmland out of production. To grow marijuana on top of the soil - they aren't even using the soil. The soil we have here is so unique. It's so important to us. We can't grow our vegetables anywhere else."

Farmers are calling for something to be done about the greenhouses and any future operations.

They say that by covering the land, there could become a drainage issue with water potentially flooding neighbouring properties.

And then there's the smell.

"The smell is overwhelming," Munshaw says. "Smoking marijuana is different than growing it. It is overpowering."

For months, farmers have been bringing their concerns to the Town of Bradford West Gwillimbury to do something.

"It's ruining my livelihood. It's definitely degraded it," claims Munshaw.

"It's very clear that there's an issue with the operations in the Holland Marsh," says Bradford West Gwillimbury's CAO, Geoff McKnight.

McKnight says the town is looking into changing the zoning in the marsh to ban future cannabis operations and to bring in a licencing system for the grow ops that already exist.

"As far as we know, we'd be the first in Ontario doing that," McKnight says.

The business licences would control things like the smell, security and operations, along with implementing regular inspections.

Munshaw says change can't come soon enough.

"This is the future for the Holland Marsh if nothing happens. It's a grow op for marijuana on top of our precious muck soils, and we're allowing them to pave over the marsh."