Merrill said her neighbor woke up on Saturday night after hearing the commotion, as the mountain lion accidentally broke a hole in the cover and nearly slipped into the hot tub.
"I'm used to the coyotes but never something this big," Merrill told CBS Los Angeles.
Neighbor Melissa Smith said she was taken aback at the sight of the massive animal in their neighborhood.
"The weirdest thing I've ever seen," she said. "Thing was huge...feet are ginormous."
National Park Service biologist Jeff Sikich said the service has been tracking the mountain lion, identified as P-55, for several months.
The mountain lion is fitted with a tracking collar, that informed wildlife officials it returned back to the mountains after its near mishap in Merrill's backyard.
