NEW ORLEANS — Five days ahead of the third anniversary of the Deepwater Horizon explosion and the ensuing underwater oil gusher, the message at a rally Tuesday in front of the Hale Boggs Federal Building was clear: It’s far from over.

Environmentalists, community advocates, elected officials and business owners gathered to express the sentiment that BP must be held accountable for the damage caused to the Gulf of Mexico’s ecosystem, economy and culture.

First and foremost it was a human tragedy, said David Muth, director of the Mississippi River Delta Restoration for the National Wildlife Federation.

Muth asked for a moment of silence to remember the lives of the 11 men killed when the rig exploded April 20, 2010.

Standing in front of the courthouse where a civil trial over the disaster is taking place, Muth said it was demonstrated that BP was driven to complete the well at all costs.

“It turned out to be very costly indeed,” Muth said.

In November, the British oil giant pleaded guilty to more than a dozen felony charges related to the 2010 Gulf of Mexico oil leak, including manslaughter and obstruction of justice, resulting in a criminal settlement of $4.5 billion.

As of March, BP had paid out about $1.7 million in claims with an estimated total of about $8.5 billion in economic, property and medical claims. In November, BP officials said they had spent $14 billion in response and cleanup costs and $1 million on restoration projects.

While the worst environmental tragedy in the nation’s history will have effects far into the future, Muth said there is also a chance to set a precedent, but only if the penalty is “costly enough to deter future disasters.”

There is also an opportunity for one of the largest environmental restoration efforts in the country’s history to take place, Muth said, but that can begin only when “BP steps up and pays their fair share or is forced to do so in this courtroom.”

Plaquemines Parish President Billy Nungesser spoke about the continued recovery of his parish — the hardest hit by the nearly three-month-long deluge of oil.

After Hurricane Isaac hit last fall, Nungesser described an unprecedented amount of dead marsh grass washing inland “100 times greater than in Hurricane Katrina.” While it’s unknown whether the grass washing up was a result of the oil disaster, Nungesser said, the loss of marsh grass has increased the parish’s risk for storm surge.

From a business perspective, chef and restaurateur Susan Spicer described stripping her menu of Gulf shrimp and oysters after the disaster and watching the businesses of friends suffer.

“The future of my businesses rely on a healthy Gulf,” Spicer said. “Restoring the environment will sustain our culture and our economy.”

Cynthia Sarthou, executive director of the Gulf Restoration Network, showed photos and samples of residual oil taken over the past three days. Looking forward, Sarthou said, there is a “once-in-a-lifetime” opportunity now to rebuild a healthy Gulf.

Jonathan Henderson, coastal resiliency organizer for the Gulf Restoration Network, opened up jars of sticky, smelly tar balls found on Elmer’s Island on Friday. Henderson said he makes four to five trips to the island each month, by foot, plane and boat to monitor the oil, whether it’s from the Deepwater Horizon or new leaks and spills.

Nungesser said he continues to get reports of oil from fishermen, but parish officials don’t always know when oil resurfaces because BP has discontinued flights over the area.

“Had it been another company I don’t think it would have been the same response,” Nungesser said. “We’ve got a foreign company that says they want to do the right thing, but they haven’t done it. This company gives all oil companies a bad name.”

The ongoing civil trial will assign liability under the Clean Water Act and determine whether the actions of BP and its contractors prior to the explosion constitute gross negligence or willful misconduct.