The Gulf Coast is expected to become the target of the largest environmental restoration effort ever as a direct result of its playing host to one of the nation's worst environmental catastrophes, according to a coalition of leading environmental groups shaping the effort.

The restoration will likely span the five-state coastal region and tap billions of dollars from settlements federal prosecutors negotiate with BP PLC and other companies deemed responsible for the 2010 oil spill.

In a detailed, 55-page report released today, the coalition laid out specific guidelines and a portfolio of projects to promote restoration and recovery of the Gulf Coast ecosystem.

Even before the 200-million-gallon oil spill, a century's worth of Mississippi River channelization to accommodate shipping, oil and gas drilling, and pollution had wreaked havoc on the region's wetlands.

Proposals outlined in the report by the coalition -- a group that includes the Environmental Defense Fund, Audubon and the National Wildlife Federation -- hints at a grand plan to undo the damage.

"In terms of actual spending, this will be by far the largest ever," said Paul Harrison, senior director for the Mississippi River at the Environmental Defense Fund. "It was a great tragedy, but it provides a huge opportunity."

The report details $1 billion in Louisiana restoration work alone -- including $690 million in projects designed to divert Mississippi River sediments to rebuild eroding wetlands -- as well as other projects across the five-state region intended to restore barrier islands, oyster habitats, shorelines, sea grasses and coral reefs.

The document's authors emphasize it is not an attempt to lay out a final restoration plan.

Instead, the report seeks to lay out examples of projects that will inform the group of trustees assembled from federal agencies, states and tribes who are working to tally up ecological damage from the oil spill, a science-based legal process known as the Natural Resources Damage Assessment (NRDA).

"What the report does is get people talking about the kind of projects that are out there to restore various Gulf resources," Harrison said.

That team will develop a restoration plan to be funded by those responsible for the oil spill and will oversee its implementation.

Environmental groups want federal prosecutors to negotiate for strong language in the damage assessment that would allow negotiations to be reopened with those responsible for the spill in the event that funded restoration efforts prove to be inadequate in promoting ecological recovery.

"We would want a very strong reopener," said Courtney Taylor, the Environmental Defense Fund's attorney and policy director for Gulf restoration. "If you anticipate that you're not going to know the damage for years, we want to be sure you can go back in."

Companies responsible, however, will likely push for just the opposite to ensure they do not continue to be held liable beyond the final dollar amount agreed to in negotiations.

Restoration efforts, in addition to those recommended by the NRDA trustees, will be funded by Clean Water Act penalties secured in settlement talks. Based on the size of the oil spill and the degree of negligence involved, penalties could range from $5 billion to $21 billion.

Environmentalists cheered Congress for passing legislation last month that guarantees 80 percent of the Clean Water Act penalties will be directed to five Gulf Coast states to fund environmental and economic restoration efforts under the auspices of a restoration council.

A final settlement, expected sometime before or soon after a trial scheduled for early next year, should take into account the scale of the ecological damage inflicted on the region, the authors said.

"They messed up big time, and they committed to make it right and they need to do the right thing," Harrison said.