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Lewis MacAdams, a poet and crusader for restoring the concrete Los Angeles River to a more natural state and co-founder of one of the most influential conservation organizations in California, has died. He was 75.

MacAdams, who died of complications related to Parkinson’s disease early Tuesday at a healthcare facility in Los Angeles, was a poet and visionary figure who led the hardened army known as Friends of the Los Angeles River and mentored generations of activists in fights to reduce the damage along the 51-mile flood control channel hemmed by freeways, power lines and railroad yards.

As the group’s first president, MacAdams was influential in making river restoration an issue for policymakers and transformed the nonprofit from a handful of nature lovers to an organization with a list of 40,000 supporters, annual river cleanup efforts and educational programs.

He also did much of the work to win approval of a $1.6-billion federal project to restore habitat, widen the channel, create wetlands and provide access points and bike trails along an 11-mile section of unpaved riverbed north of downtown.

Read the full story on LATimes.com.