Ever since the "Lost" producers cut a deal with ABC to conclude the series after six seasons, it's become fashionable for people to say Show X or Y would be wise to set an end date, even though most of the TV business works under the assumption that the longer a show lasts, the better it is financially, if not creatively. HBO doesn't operate according to those rules, and even within HBO, David Simon marches to his own drummer, which is why he's begun suggesting that "Treme" should probably end after four seasons - even though at the moment the show is only guaranteed three.

As first reported by New Orleans Times-Picayune TV critic and all-around "Treme" expert Dave Walker (whose "Treme" Explained pieces are essential reading after every episode), Simon, co-creator Eric Overmyer and producer George Pelecanos recently got together to discuss the long-term arc of the series, and concluded that four seasons would probably be the ideal length. Simon then sent a memo to HBO explaining that and detailing their plans for that hypothetical fourth season.

Since Walker's piece was published earlier this week, the details have gotten mangled in certain places in that usual game-of-Telephone way that the Internet operates, so I emailed Simon for some clarification.

"It seems to be out there that i said we would be doing four seasons," Simon wrote back. "I didn't say that exactly.  I told Dave Walker that the writer-producers met twice over the hiatus for a week at a time and plotted all the storylines and determined that two more seasons was the optimum for the vast majority of characters, for the theme, and practical for the history of post-Katrina New Orleans.  That we would have a hard time finishing in three, or, unless some other avenues for storytelling revealed themselves organically, extending the drama to five seasons."

At the same time, he recognizes that it's entirely up to HBO bosses Michael Lombardo and Richard Plepler to decide whether they want a fourth season, and that "HBO has made no decision and I don't expect a decision until we meet with them -- at the earliest."

If the show sticks to a timeline where each season begins roughly a year after the one before it started, we would need a fifth season to get through the New Orleans Saint's Super Bowl win and the BP oil spill, which seem the kind of good news/horrible news mix that would be appropriate for a David Simon-style finale. But it may be that Simon and company don't want to take the characters that far, or else that there will be longer chronological gaps between the events of seasons two and three, and then between three and the hypothetical four.

But all we know for now is that Simon ultimately doesn't control when the show ends. As he put it, "Fools plan. Networks decide."

(HBO hasn't yet announced a premiere date for the third season, but based on precedent, expect sometime in the spring.)