Workers remove containment boom from water contaminated by oil from the Deepwater Horizon spill, Thursday, June 10, 2010, in Bay Barbeau near Chauvin, La. ((Eric Gay/Associated Press))

A study started two years before the devastating oil spill in the Gulf of Mexico suggests resources valued at $1.3 trillion US are at risk from the oozing crude.

The study by Earth Economics of Seattle was released Thursday after researchers refocused it to gauge the impact of the spill. The report also factors in environmental degradation from oil and gas activity in the region over the years.

The trillion-dollar figure is based on the economic and human impact of the Mississippi Delta region, according to John Day, professor emeritus in the Department of Oceanography and Coastal Sciences at Louisiana State University.

"Just as an ecosystem is providing habitat and the organisms that we harvest, it provides storm protection and cleans water," Day said in an interview with CBC News. "And it has aesthetic and spiritual values, it supports tourism; you know there's a very long list of these services that natural systems do and they're absolutely essential to the maintenance of healthy economy."

"These huge numbers show that the BP oil spill, hurricanes and continued wetland degradation threaten not only the Gulf regional economy, but the national economy," said David Batker, executive director of Earth Economics, and a co-author on the report.

It's unclear how much oil has poured into the Gulf since a drilling platform exploded in mid-April. So far, the crude has soiled 190 kilometres of Gulf coastline, and Florida's coast is also seeing the impacts of the spill.

The report suggests direct economic costs from the spill are between $12 billion and $57 billion.

"A large part of the Louisiana coastal fishery is shut down right now. A large part of the tourist industry along the coast involving fishing, but also people going to the beach, you can't go to those places, so people are suffering an economic impact right now," said Day, a longtime resident of the Mississippi Delta region.

A separate report suggests the cost to Florida will be $11 billion, and cost 195,000 jobs.