07/21/2014 07:30 EDT | Updated 09/20/2014 05:59 EDT

Shepherd stands as sentinel of Saskatoon's swale

Wild fires and roaming herds of bison used to be the protectors of the northeast swale, helping to keep the unique patch of prairie healthy by keeping invasive plant species at bay.

Today, there’s a new keeper of the swale.

Jared Epp is the sentinel, on the watch for things like leafy spurge and sow thistle.

Epp is a shepherd. His main weapon in the fight to save the swale is a flock of sheep

Hundreds of sheep are at work on the swale, munching away on invasive plants.

"They are going around getting what they like and it just happens to be that those are the things that we want to get rid of," Epp said. "Very minimal impact on the species that are preferred and high impact on the ones that are not preferred and so it's just the perfect tool."

Epp is under contract with the Meewasin Valley Authority (MVA). The MVA is charged with managing and protecting the sensitive prairie region.

It’s an important task, as city development draws closer.