(KTEN) -- Yes, that is smoke in the skies over parts of Bryan and Grayson counties this week.

The fires were set intentionally by the US Army Corps of Engineers during park ranger training camp at Lake Texoma.  

The controlled fires aren't always part of the curriculum, but because of certain circumstances they were this year. The fires help maintain the health of a forest.

"There's more to the course than just going out and setting a fire," said Billy Williams, Chief Park Ranger at Lake Texoma. "You need to know wind direction, humidity... so that's the type of class training that they get indoors. Then they get to apply that outdoors with actually setting the prescribed fires."

The students burned around 350 acres Wednesday at West Burns Run at Lake Texoma. 

They will be doing another controlled burn this Friday, February 26.