"Black Water" became the Doobie Brothers' first song to reach No. 1 on the Billboard Hot 100 on March 15, 1975 – but it took an unusual series of series of events to make it happen.

"Another Park, Another Sunday," the first single from 1974's What Were Once Vices Are Now Habits, eked into the Top 40. But according to the Tim Morse book Classic Rock Stories: The Stories Behind the Greatest Songs of All Time, Doobies co-founder Tom Johnston said he believed its chart life was shortened thanks to a lyric about how "radio brings me down" – something station program directors didn't take kindly to.

When subsequent single "Eyes of Silver" failed to gain traction, Warner Bros. took the odd approach of sending a three-year-old track, "Nobody," to radio on Nov. 15, 1974. Fortunately, while all these shenanigans were going on, DJs were busy discovering the b-side for the Doobie Brothers' "Another Park, Another Sunday."

"Black Water" boasted a laid-back vibe, and a decidedly more bluegrass-influenced sound than early hits like "Long Train Runnin'" and "China Grove." Patrick Simmons tells the story of time spent floating down the Mississippi River on a homemade raft, all set to a beautifully laconic melody supported by a delicate acoustic guitar and Appalachian strings.

"I was fooling around with this open-tuning thing in the studio and I started writing some lyrics about New Orleans," Simmons told the Sun Herald. "I was spending a lot of time there. The lyrics 'If it rains I don't care, don't make no difference to me, just take that street car that's going Uptown' is a true story — as is 'I want to hear some funky Dixieland,' because there was a lot of Dixieland bands playing in the French Quarter."

While most listeners probably hadn't spent time watching catfish jumping under a Mississippi moon, just about everyone can understand lines like "I ain't got no worries / 'Cause I ain't in no hurry at all." That isn't just a classic rock couplet, it's a manifesto worth aspiring to.

Listen to the Doobie Brothers Perform 'Black Water'

"He was just writing on his acoustic guitar," What Were Once Vices Are Now Habits producer Ted Templeman later told Billboard. "We laid it down on an acoustic guitar track with a rhythm machine, which in those days was pretty unheard of, and then we overdubbed the drums and the rest of it."

And then, of course, there's that "Black Water" breakdown. One of the most recognizable a cappella arrangements in rock 'n' roll was suggested by Templeman, a former member of Harper's Bizarre who remembered the trick from his old group's cover of the Simon & Garfunkel song "The 59th Street Bridge Song (Feelin' Groovy)."

Lenny Waronker "did the same thing for 'Feelin' Groovy' where he pulled the track out," Templeman added, "so I stole the idea from my old producer."

"Black Water" suddenly became one of the Doobie Brothers' signature songs. "I remember when I first heard it was No. 1, we were in Baton Rouge, La., and we were just getting ready to go onstage," Johnston told Songfacts. "I guess [band manager] Bruce [Cohn] must have told us. I remember I went in and congratulated Pat backstage – and we've been playing it ever since."

A substantial portion of its appeal rests on those supremely mellow lyrics, but the track was also helped by the fact that it didn't sound like anything else on the radio at the time – and really, it still doesn't.

"It started off as an acoustic song, just an acoustic guitar for the first third of the record, then the drums come in," said Templeman, when asked to analyze the success of "Black Water." "Records weren't like that on the radio. There were formula pop records then. There's little things that speed up and slow down because we didn't stay right with the rhythm machine, but it's a pretty good record."

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