Myrtle Grove — Gone are the thick black globs of oil covering the marsh grass. Gone are the white cords of absorbent boom and blasting cannons used to scare birds away. Gone are the teams of workers — charged with cleaning the marshes without accelerating the already rapid erosion.

Almost three years after the Deepwater Horizon oil platform exploded, killing 11 men and spewing about 210 million gallons of oil into the Gulf of Mexico, Bay Jimmy is quiet.

But the big questions still remain, said David Muth, director of Mississippi River Delta Restoration for the National Wildlife Federation. It is not known to what the extent the most toxic components of the oil have entered the ecosystem, Muth said.

The suffocated marshes and oiled birds were obvious effects, but less observable is how much and how far the toxins — the lighter fractions of the oil — dissipated into the environment, he said.

On Tuesday, Muth toured the area to bring attention to two major concerns. First, he said the federation wants to make sure the responsible parties pay everything owed under the law. Second, he said they want to make sure that money is put to good use — real restoration.

The lonely marsh island sits at the northern end of Barataria Bay, about two-thirds of the way from New Orleans to the Gulf of Mexico. At one time, ground zero for oil inundation and cleanup, it is now ground zero for monitoring and research.

Bamboo poles mark how much of the island’s shoreline has receded since the oil hit, in places as much as 150 feet.

As charter boat captain Chad Daigle navigated through the marshy maze, he recalled the first time he saw the area blanketed under thick oil. “When you see it somewhere else, it doesn’t affect you like when you see it in your own backyard,” Daigle said. “I’ve never seen so much oil piled up and thick on the water and hopefully will never see it again.”

BP is doing exactly what big corporations are expected to do, Muth said: Launch a massive public relations campaign to show that everything’s back to normal on the Gulf Coast. Some things are, he said, but the extent of the damage remains an unknown.

A tiny black crab crawled across Muth’s forearm. “How much oil is this crab carrying?” he asked. From the toxins absorbed into the grass, to organisms eating the grass, to other creatures eating the organisms and so on up the food chain, the toxins can amplify, he said. “Some chemicals are certain to have persisted.”

The oil’s impact on erosion is still being studied as part of the Natural Resources Damage Assessment in terms of how quickly oiled areas eroded compared with the normal rate of erosion, National Wildlife Federation staff scientist Alisha Renfro said. Most of the data is not yet available to the public and is still tied up in the ongoing litigation, Muth said.

But with $1.2 billion already in the pipeline, Muth said it’s crucial to quickly move forward on restoration projects as outlined in the state’s 2012 Coastal Master Plan.

The river diversions outlined in the plan are “absolutely critical,” Muth said. “Without those, we are wasting time and money and might as well pack up and go,” he said.

Muth said the proposed Mid-Barataria diversion, near Myrtle Grove, will at peak capacity move 75,000 cubic feet of valuable land-building Mississippi River sediment into the disappearing marshes most heavily damaged by the oil.

Rather than dumping the sediment off the continental shelf in the Gulf or depositing it onto the riverbed, the diversion will mimic the river’s natural process and again stimulate the ecosystem through annual flooding, Renfro said.

While there is only about half as much sediment in the river as there was in the early 1900s, Renfro said that there is still enough to make a difference. It’s not enough to rebuild all of southeast Louisiana, she said, but can build a significant amount of land with strategic planning — and by making some difficult choices.

There is always opposition to diversions, Muth acknowledged, and oyster harvesting and fishing will be affected as the salinity line shifts.

And communities will be affected — namely Jean Lafitte, Renfro said, for which there will have to be other measures taken, such as raising more homes and constructing ring levees.

Muth acknowledged apprehension to changes brought by the diversion, but “the idea that there has ever been any permanence is not true.”

Fingers crossed, construction on the diversion could start in two years, he said. Despite all the uncertainties, “What we do know is that we lose land with every second of delay,” he said.

Based on varying levels of subsidence and in the face of sea level rise, it’s essential to determine what areas have the best chance of rebuilding given limited resources, Muth said. With every grain of sediment moved, we want “the most bang for our buck.”

While other projects like pumping sediment and replanting marshes are important, without fundamentally changing the system, those efforts are simply stopgap measures — buying time, Muth said.

Muth called the master plan an “incredibly good blueprint,” and an opportunity to turn the corner from a system in a stage of decline to one day reaching equilibrium. It will be centuries before the delta will be rebuilt, he said, but in decades it has the potential to reach a point where as much land is being built as is being lost.

Part of the brilliance of the plan is in its adaptability, he said. A project that looks good in 2012 may not make sense 10 years later and built into the plan is a process of required re-evaluation every five years.

It’s worth the effort, Muth said. The importance of this habitat cannot be overstated, he said.

“It’s wildlife, it’s fisheries, it’s culture, it’s a way of life,” he said. “To sit back and give up is not an answer.”