Mary Mara has died at the age of 61 after drowning, according to New York State Police.
A report, published on Monday, said the body of the American actress was discovered on Sunday in the St Lawrence River, in the town of Cape Vincent, which lies about 90 miles north of Syracuse.
Ms Mara was believed to have been staying at her sister’s summer home, which fronts the St Lawrence River, when she decided to go for a swim.
An autopsy has been ordered with a preliminary investigation suggesting she drowned while swimming.
As per the report which was obtained by The Hollywood Reporter, there were no signs of foul play.
A representative of the star confirmed her passing to Fox News Digital, saying: “Mary was one of the finest actresses I ever met. She had a terrific sense of humour and a unique outlook on life.
“I still remember the first time that I saw her onstage in Mad Forest in 92. She was utterly captivating, well loved, and will be missed.”
Ms Mara’s career in TV and film spanned three decades and saw her appear in more than 20 movies and 40 television shows.
The actress was best known for playing Inspector Bryn Carson on Nash Bridges and Mrs Sullivan on Ray Donovan.
She also featured as Loretta Sweet on ER and Nance in Shameless, and also gained roles on hit shows such as Star Trek: Enterprise, Lost, Law & Order: Special Victims Unit, West Wing, NYPD Blue and Nip/Tuck.
Her last credit, according to IMDB, was a role in the 2020 film Break Even.
She is survived by an ex-husband and stepdaughter.