Doc Gaston is the Racket Boss who runs the drugs racket in the French Ward for Lou Marcano. A doper and something of an outsider, Doc Gaston would get a lot of friction for being half-hippie, if everyone wasn't already completely terrified of him. 
Dope is everywhere in the French Ward, but you have to go through Gaston's people to get it. He has his dealers working around the clock to keep both tourists and locals nice and high, and immediately sends his men after potential competition.
Gaston's pushers, Eugenio Calabrese, Franz Nero, and Buster Nunez, manage a large network of street dealers to keep a regular flow of drugs coming into the Ward. Their supply is brought in via boats, with drop-off points at a local boathouse and a dock behind a private mansion. Bagmen are responsible for picking up cash from the dealers and delivering it to a stash house for counting and safekeeping, before it's funneled back to Gaston and Uncle Lou.
In 1968, Gaston's racket was taken over by Lincoln Clay, who was working with inside information he received from NBPD detective Jim McCormick. Lincoln damaged Doc's drug operations by killing his enforcers, pushers, and dealers, as well as damaging the racket's assets. Once everything fell apart, Gaston resurfaced, giving Lincoln the opportunity to confront him. After successfully infiltrating the Cistern, Lincoln dealt with Gaston and ended his association with the Marcano Crime Family.