Lewis MacAdams, described by those who knew him as a pioneer in preserving the Los Angeles River, died Tuesday at the age of 75.
"One of this city's truest angels, my dear friend, mentor and high school teacher, Lewis MacAdams, has passed,'' Mayor Eric Garcetti announced on Twitter. "He touched our souls, changed my life and resurrected our river. See you downstream, brother. #lariver."
According to the Los Angeles Times, MacAdams died at a health care facility in Los Angeles of complications related to Parkinson's disease.
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He was a poet who founded and led the Friends of the Los Angeles River and mentored generations of activists in fights to reduce the damage along the 51-mile flood control channel.
The river was bedded by concrete and walled off by a fence in 1938, according to the Friends of Los Angeles website.
"In an act of civil disobedience, poet activist Lewis MacAdams took the first steps to repair that severed connection in 1986 when he cut a hole in the chain-link fence that obstructed Angelenos from their rightful river," the website reads. "He declared the river open to the people and swore to serve as its voice."
The organization, which has grown to more than 50,000 members, works to restore the river and advocate for policies to protect its natural existence.
Councilman Mitch O'Farrell said MacAdams' vision and stewardship helped pave the way for the river's restoration.
"Lewis MacAdams is an environmental hero and a legend in Los Angeles," O'Farrell said. "He will always be our spirit guide on the revitalization of the Los Angeles River. His poetry is a testament to the peace and serenity of nature at our city's urban core.
"Where others saw a concrete channel, Lewis saw incredible beauty and resiliency. He knew the river's potential because he understood its past," the councilman said, adding that MacAdams helped Los Angeles' leaders view the river as a "centerpiece for the city's renaissance."
MacAdams is survived by sons Ocean, Will and Torii; daughter Natalia; brother Alan; sister Kathy; and his companion, Sissy Boyd, according to the Times.
Memorial arrangements were not immediately available.