Narrated by John Waters. Unrated. Plays Friday to Sunday, July 20 to 22, at the Pacific Cinémathí¨que

You can tell from the forced poetry of the title Plagues and Pleasures on the Salton Sea that this documentary is a little too ambitious for its own good. From what we see in this amusingly assembled essay; already stretched a bit at 73 minutes; there are few plagues and not all that many pleasures to be found in this artificial lake in the Colorado Desert in Southern California.

This artificial paradise; for readers not up on SoCal arcana and the latter-day passions of Sonny Bono; was created 102 years ago when an engineering mistake sent massive runoff from the Colorado River into what was then known as the Salton Sink. Over the decades, California's largest lake became ever more concentrated in its salinity and is now an important home to waterfowl as the wetlands steadily recede. Its fashions rose and fell as a resort intended to rival Palm Springs to the north. Instead, floods and droughts, rising temperatures, greedy developers, insensate politicians, and millions of dead fish turned it into what one crusty resident calls "the world's largest sewer".

The background material, presented early by writer-directors Chris Metzler and Jeff Springer (who both also shot and edited the doc), is particularly enjoyable. The project has an irreverent pull, underscored by colourful art direction, whimsical narration from John Waters, and cool, twangy guitar music from the Friends of Dean Martinez.

The problem is in the not-quite-endless parade of talking heads arguing about the past and future of the Salton Sea. Along with a game warden, cynical old-timers, a chatty greasy-spoon waitress, local kooks, escapees from the inner city, an assortment of land speculators, and (most regrettably) a Hungarian immigrant who learned more about drinking beer than speaking English, there is a disarmingly good-natured fellow building a mountain out of Bible quotes and a skinny nudist who spends his days (literally) waving at motorists.

After a while, I lost interest in their stories, which sometimes have the whiff of being told too often. But I perked up again at the wrap-up, telling of the late Mr. Cher's attempts to revive interest in the lake, which, if untended, will eventually evaporate to the point where Palm Springers can look forward to a future full of alkaline dust on the wind. The locals may be eccentrics, but the movie makes it clear that they are not as far away as they seem.