Rivera, 33, was presumed dead after she went missing Wednesday.
Her body was found floating in the northeast area of the lake where the water is between 35 and 60 feet deep Monday, after a six-day search. Ayub said investigators are "confident" the body found was Rivera, but the body is still being taken to Ventura County Coroner's Office, where it will be identified through dental records.
Ayub said the sheriff's department has been "in direct contact" with Rivera's family.
"Her family has been at the lake everyday holding out hope and communicating with our investigators," Ayub said.
The actress is best known for her role as Santana Lopez on the Fox show "Glee," which quickly won critical acclaim after debuting in 2009. She appeared in nearly every episode of the beloved musical-comedy-drama, which ended in 2015.
Rivera's fellow "Glee" cast members Cory Monteith and Mark Salling have also died.
Members of the show's cast took to social media to mourn their costar, sharing their condolences to Rivera's family.
"How can you convey all your love and respect for someone in one post?" Chris Colfer, who played Kurt on "Glee," wrote on his Instagram
in a lengthy, emotional caption of a picture of him and Rivera. "How can you summarize a decade of friendship and laughter with words alone? If you were friends with Naya Rivera
, you simply can't."
"Rest sweet, Naya," Jane Lynch, who played Coach Sue Sylvester on the show, tweeted
. "What a force you were. Love and peace to your family.
Rivera was also on the CBS sitcom "The Royal Family" and in the comedy film "The Master of Disguise." More recently, she starred in the "Step Up" television series, based on the movie franchise./CNN