Deputies have identified that woman as 35-year-old Brandi Humphrey of Grand Rapids.
Humphrey’s fiancé tells FOX 17 that she jumped off a pontoon boat into the lake Sunday afternoon and believes she may have started to struggle because of the water’s temperature.
He said that he and his brother attempted to get a life jacket to her, but wind caused their boat to drift and they were unable to get to her in time.
Residents near Kimball Lake said the area where Humphrey is believed to have vanished is the deepest part of the lake, estimating the depth at roughly 50 feet.
Follow FOX 17’s Dana Chicklas on Twitter for live updates from the scene