CHICAGO – On Tuesday a U.S. judge approved a $1 billion settlement for civil penalties against the rig operator involved in the 2010 Gulf of Mexico oil spill, the worst environmental disaster in American history.

The decision came after a $400 million settlement of criminal penalties against Transocean was approved last week.

"The Court finds that there is no just reason for delay and therefore the Court enters this Consent Decree as a final judgment," wrote Judge Carl Barbier of the U.S. District Court for the Eastern District of Louisiana, in New Orleans.

The blowout on the drilling rig Deepwater Horizon on April 20, 2010, killed 11 people and sent 4.9 million barrels of oil gushing from the sea floor into the Gulf.

Transocean pleaded guilty to one criminal count of violating the Clean Water Act and agreed to pay the $400 million fine for negligence that led to the explosion of the Deepwater Horizon rig.

The $1 billion civil penalty is for fines related to the oil spilled into the Gulf.

It is also responsible for implementing measures to improve operational safety and emergency response capabilities at all their drilling rigs working in waters of the United States.

The Swiss-based drilling company was operating the rig for British energy giant BP, which for its part was fined $4.5 billion over its role in the disaster.

The crude flowed in uncontrolled fashion for almost three months in a tragedy that riveted the nation.

In total, the amount of fines and other criminal penalties imposed on Transocean are the second-largest environmental crime recovery in U.S. history, after that slapped on BP.

Transocean must pay $400 million of the civil penalties within 60 days and another $400 million plus interest within a year. The remaining $200 million must be paid, again with interest, within two years.

Copyright Agence France-Presse,  2013