Rivera, 33, disappeared during a boating trip with her four-year-old son last Wednesday, and her body was found floating in Lake Piru on Monday.
The Ventura County Medical Examiner’s Office formally confirmed Rivera’s identity using dental records, it said in a statement.
No traumatic injuries or evidence of alcohol or other toxins were found.
On Monday, Ventura County Sheriff Bill Ayub said there was no indication of suicide, and suggested that the lake’s strong currents could have caused a fatal accident.
“The idea perhaps being that the boat started drifting — it was unanchored — and that she mustered enough energy to get her son back onto the boat, but not enough to save herself,” he said.
Her son was found asleep and drifting in the boat some three hours after Rivera rented it at the popular recreational hotspot around an hour’s drive northwest of Los Angeles.
Hollywood stars paid tributes to Rivera, including her former castmates on smash-hit musical television series “Glee,” some of whom gathered at the shore of the lake on Monday.
Chris Colfer said Rivera “spoke truth to power with poise and fearlessness,” while Jane Lynch wrote on Instagram: “Rest sweet, Naya. What a force you were.”
Oscar-winning actress Viola Davis wrote: “Prayers for Naya Rivera’s family. Man… can we have a ‘Do Over’ of 2020. The loss is too much.”