While Gulf Coast residents and environmental groups focus on the upcoming five-year anniversary of the Deepwater Horizon disaster, a damning Associated Press investigation has exposed the lingering impacts of a separate 2004 leak in the Gulf of Mexico—one that few people know about, and one that is far worse than the industry wants to admit.

Taylor Energy Company, which formerly operated the oil platform that collapsed during Hurricane Ivan, "has downplayed the leak's extent and environmental impact, likening it to scores of minor spills and natural seeps the Gulf routinely absorbs," according to AP journalists Michael Kunzelman and Jeff Donn.

The article, published Friday, continues:

[T]he spill is far worse than what Taylor—or the government—have publicly reported during their secretive, and costly, effort to halt the leak. Presented with AP's findings, that the sheen recently averaged about 91 gallons of oil per day across eight square miles, the Coast Guard provided a new leak estimate that is about 20 times greater than one recently touted by the company. Outside experts say the spill could be even worse—possibly one of the largest ever in the Gulf.

According to the AP, "Taylor's oil was befouling the Gulf for years in obscurity before BP's massive spill in mile-deep water outraged the nation in 2010."

Yet "[E]ven industry experts haven't heard of Taylor's slow-motion spill, which has been leaking like a steady trickle from a faucet, compared to the fire hose that was BP's gusher."

The AP produced a video about the spill, which the news agency says "has no end in sight":