US congressman Doug LaMalfa died Tuesday at the age of 65, according to his office.
It did not disclose the cause of death of the California Republican but described it as "unexpected."
President Donald Trump recognized LaMalfa's death during a speech at a House Republican retreat at the Kennedy Center, describing him as a "fierce champion on California water issues" and commending his loyalty.
House Speaker Mike Johnson said Congress is "devastated" to learn the news.
"Doug was a lifelong resident of northern California and deeply loved its people. He was as fierce of a fighter for his state's vast natural resources and beauty as we have ever known," he said in a statement.
California Gov. Gavin Newsom said LaMalfa was a "devoted public servant who deeply loved" his country.
Flags at the State Capitol and Capitol Annex Swing Space will be flown at half-staff in honor of LaMalfa.
