"It's putting our supply of water at risk," says Sylvie Jensen.
"The community here is on well water. The production of cannabis requires a lot of water per plant per day and this aquifer is already overtaxed."
Tantalus Labs, the company behind the project, isn't commenting on the protest, but said in a brief statement that it hired an independent hydrology consultant who found there is no reason for residents to worry about their well water.
But despite that, many of the residents aren't convinced.
"[They're] telling us we shouldn't worry. We shouldn't worry about the water and it's not going to have a negative impact on us and everyone's wells, but the reality is, it will. It has to."
Other residents are concerned the site is too close to the local elementary school.
Health Canada still hasn't decided whether it will grant Tantalus a licence for marijuana production, but the demonstrators hope the size of the protest will send a message that's loud enough to be heard all the way in Ottawa.