MISSOULA, Mont. - Summer is around the corner, the grass is green and the weeds are growing.
That means it's time for Missoula's elite team of noxious weed fighters to hit the hills.
To the naked eye down in the city it may not look like it, but Missoula rancher John Stahl tells us these dangerous weeds were a lot taller when his sheep started.
"You couldn't hardly even see my sheep through the leafy spurge and the knap weed," said Stahl.
Stahl tells NBC Montana he's happy to put his wooly friends to work munching noxious weeds every summer.
"That gives those native plants a chance to go back to blooming and reseeding," he said.
Stahl's worked with the city to get the sheep on the north hills and mount jumbo every summer for the last 12 years.
"Today you walk up there and the sheep are plain out in sight," said Stahl. "It's easy to see them because the spurge is gone and the grass is starting to grow up and really fill in."
Stahl tells us leafy spurge and knap weed are two great examples of the types of noxious weeds his fluffy friends will be eating over the next few months.
Missoula hiker Lindsey Salmonson says she'd rather hike with sheep then pesticides.
"Reducing impacts of and removing invasive species is important because it can be really harmful spraying and everything like in public places," said Salmonson.
Stahl says it's a win-win for the city, hikers and himself.
"My profitability is up because I'm on the mountain and it's really been a big help," said Stahl. "I didn't realize this was going to happen when it first started, it's just kind of evolved."
Stahl tells NBC Montana the whole experience is rewarding.
"They (hikers) come walking up and they say man it has really made a difference up there, the weeds are way down and we appreciate that," said Stahl. "That's what makes my day."
The sheep will work in the North Hills for the next week then it's off the Mount Jumbo until August.
An important side note to this story - if you have a dog off leash, at either of these locations, and it attacks a sheep you can be cited and may face a charge for "dog at large." The court can then levy you a fine up to $275 and you will have to pay to replace the sheep; Stahl tells us they cost roughly $300/head.