The column of dirt, 15 feet of gloppy mud extracted from beneath the murky Anacostia River, has a story to tell.

It speaks of the changing composition of the river’s sediment over the past century — sometimes sand, sometimes silt, sometimes gravel, sometimes clay. It offers up a candy wrapper, a piece of a bottle, even a golf ball that went astray in the 1950s and has stayed at the river’s bottom until now. When the color of the mud changes from milk-chocolate brown to petroleum black, the dirt is proclaiming loud and clear the pollution of yesteryear.

By laying bare these stories of the watery past, pulled from the depths, the District’s environmental department hopes to write a cleaner tale in the mud of the future.

These pillars, more than 130 total, are being extracted from the Anacostia in the first stage of an ambitious and expensive project to map toxins in that dirt and remedy the pollution.

The D.C. Council committed last year to completing a plan by June 2018 for cleaning up the river and then to carrying out that plan. Lawmakers and activists talk about the day, after the cleanup is done in a decade or more, that children will be able to learn to swim in the Anacostia’s waters and residents will be able to feast on fish they catch themselves.

Reaching that idyllic vision of clean water starts with a prolonged investigation into just how dirty the water is now.

Tommy Wells, director of the District Department of the Environment, went on a boat to look at progress of that investigation earlier this month.

A 16-member crew from Tetra Tech, a firm contracted by the District, plans by the end of May to finish collecting dozens of samples from the water, fish and riverbed.

Watching the technicians dip a set of steel jaws into the murky water, Wells said, “It’s like that arcade game.”

He asked what polluted this particular part of the river and was told that the Navy used to manufacture ships nearby. “So Poplar Point, even though it looks pretty green and lush, it’s a pretty nasty place?” he asked.

He joked about learning firsthand how badly the Anacostia needs cleaning. “I’m not proud of this, but I flipped my sailboat over by the airport. So I’ve been in this water.”

Tetra Tech employee Ryan Murley, right, takes an initial survey of a sediment sample from the Anacostia River in Washington. (Linda Davidson/The Washington Post)

But he won’t commit to seeing that cleanup happen soon. In fact, he said, he isn’t sure the Department of the Environment will meet the June 2018 deadline that the D.C. Council set when he was a member.

“Until I know more about the whole process of doing this right now, I’m not going to commit to that date,” he said. “I think it’s very possible to meet the council deadline. . . . I’m not able to certify yet that we will make that date. But we will get there.”

When the boats are finished scooping up water and sediment samples, Tetra Tech will complete a report on which spots are polluted by what.

At that point, the Department of the Environment will come up with a plan for fixing the pollution, most likely by dredging or putting a cap over the worst spots, according to river cleanup experts.

And then, according to federal law, whichever parties have been found to be responsible for the pollution will be required to help pay to clean it up. Those parties might include any of the entities that have operated along the Anacostia for generations: companies such as CSX, the utilities Pepco and Washington Gas, and federal agencies such as the Army at Fort McNair and the Navy at the Navy Yard.

In similar circumstances in other cities, divvying up the enormous amount — project manager Dev Murali of the Department of the Environment said it could approach $1 billion in the Anacostia River case — has led straight to a courtroom.

Wells said he wants to avoid a court fight in the District, although environmental activists say that is unlikely.

“The different parties that will be responsible, I really want them to be on board. I don’t want to have to decide this in a courtroom,” Wells said. “I really don’t want to see [a scientific report] that’s easily challengeable. We really need to back this up by rock-solid science.”

What the science looks like, this month, is an iPad on a noisy boat on the Anacostia, telling Tetra Tech contractors where they should hang the vibrating machine over the water and drill through an opening in the bottom of the boat to press a stainless steel core into the earth.

It’s a base along the water where those cores, four inches in diameter and filled with sediment, are hoisted onto land and then cooled in a free-standing, walk-in refrigerator that keeps volatile compounds in the dirt from escaping.

It’s a tent where the plastic sleeve inside one of those metal cores is slid out and then sliced open with a drill. It’s two scientists quickly sniffing that dirt, some of it exposed to the air at that moment for the first time in a century, with both an electronic nose and their own noses, for the scent of petroleum components.

“Often the first indication of whether you have a clean core or a dirty core, if I can use two categories like that, is when you crack it open — the smell,” said Brad Schrotenboer, a technician for Tetra Tech. He moved methodically down the core, from the most recent sediment at the top toward the older stuff at the bottom. Inch by inch, he peered at the dirt to check its consistency and color, rubbed it between his fingers, and picked up chunks to hold to his nose.

With each break in the core’s composition, Schrotenboer and colleague Ryan Murley filled jars with the mud, to be sent to a lab in Pittsburgh that will analyze them.

Those samples will be tested for all of the suspected pollutants of the past: mercury, cyanide, carcinogenic PCBs and about a half dozen others.

“Every core tells a story,” Schrotenboer said.

“It’s a real look back into the past,” Murley added.

And if their work leads to a swimmable, fishable Anacostia, then that long-buried core is also a look into the future.