When Hurricane Ivan struck the Gulf of Mexico off of Louisiana in 2004, the force of the waves prompted a mudslide that toppled an offshore well platform owned by Taylor Energy. Since then, more than 10 years ago, oil from the undersea wells has been leaking into the Gulf unabated.

And the leak is far larger than reported.

According to an Associated Press investigation, recent U.S. Coast Guard figures show that the volume of the continual spillage is 20 times higher than figures originally put forth by Taylor Energy.

Taylor Energy for years reported that the volume the leak was declining: from 22 gallons per day in 2008, it was said to taper down to 12 gallons per day over the following five years. But the 2,300 pollution reports analyzed by the AP didn’t match those figures.  Rather than decline, the pollution reports documented a dramatic spike in the size of oil sheens and the volume of spilled oil since September 1, 2014, just after federal regulators began sending government observers on the observation flights with the Taylor contractor that had been reporting spill volumes. A Taylor spokesman declined to comment on AP’s findings.

The federally managed effort to stop the flow of oil has been “shrouded in secrecy,” according to the AP. Now, U.S. Senator Bill Nelson (D-Fla.) is urging the government to release documents related to the spill and mitigation efforts.

On Friday, Nelson sent a letter to Interior Secretary Sally Jewell and Department of Homeland Security Secretary Jeh Johnson that stated “all necessary resources” should be put toward stopping the leak. He also urged the government to release data on how much oil was estimated to be streaming from the wells since the leak began in September 2004, as well as aerial and subsea images of the leak site.

Meanwhile, according to the AP, Taylor Energy sold off all of its offshore assets in 2008, and currently has only one full-time employee.