AMNA NAWAZ: An historic sewage spill along the Potomac River and the struggle to contain it are raising alarms after a major sewer line collapsed late last month, sending over 240 million gallons of waste into the water.

For nearly a week, raw sewage flowed directly into the river, before it could be diverted to a treatment facility.

Yet reports of intermittent spills have continued into February, and repairs are expected to take more than a month.

Public health experts say it could be one of the largest sewage spills in American history.

For more, I'm joined by Hedrick Belin.

He's president of the Potomac Conservancy.

Thanks for being here.

HEDRICK BELIN, President, Potomac Conservancy: Appreciate the opportunity.

AMNA NAWAZ: So let's just start with the obvious question here.

How polluted is this water after all of that sewage spilled for as long as it did?

What do we know?

HEDRICK BELIN: Well, it was certainly unprecedented, in terms of the amount of sewage going into the Potomac River, which is our nation's river, over just a week.

And water quality sampling efforts have shown astronomical levels of pollution, well, well above the EPA guidelines for what is safe for humans to touch.

And so there's a lot of work that needs to be done to address this, both in terms of the river health, but also the remediation that's going to be needed to ultimately restore the area to a place where people can splash around safely.

AMNA NAWAZ: Before we get to people in the water, what are some of the bigger environmental concerns?

What are you looking at?

HEDRICK BELIN: Well, I think at a macro level, the good news is, over decades, the Potomac River's gotten a lot better.

We come out with a river report card every couple of years, and the Potomac's clearly making a comeback.

But, unfortunately, we saw, when we released it, for example, pollution levels going down, fish populations doing better, and more people out recreating, but this amount of pollution is going to certainly change that equation.

But it also raises another interesting point, which is, this is a 54-mile-long pipe full of sewage that starts out near Dulles Airport.

And where else is the pipe susceptible to breaking?

AMNA NAWAZ: That's a big question you think we still don't have answers to.

HEDRICK BELIN: We don't have answers to that just yet.

AMNA NAWAZ: So one of the biggest questions we have heard from people in terms of the impact is on drinking water.

Do we know if this is having an impact on people's drinking water in the region?

HEDRICK BELIN: Well, the good news is, this happened just downstream of the -- where two big straws go in to take in water, drinking water.

And about five million people in the D.C.

metro area get their drinking water at home and here from the Potomac.

So we were fortunate that it happened downstream of those drinking water intakes, but it's still going to be problematic for months to come.

AMNA NAWAZ: And in terms of what we know about the spill, what does all of that mean for the risk of people going into the water?

Sounds like you don't recommend right now.

HEDRICK BELIN: No, you should stay away.

AMNA NAWAZ: For how long?

HEDRICK BELIN: Yes, you should stay away.

And for how long is unknown.

There's - - we're going to need to see continued water quality testing every day, we believe for another six months.

AMNA NAWAZ: Six months.

HEDRICK BELIN: Because even when the pollution levels are down where it's safe, the risk -- it's such a active situation that the risk for additional pollution going in, additional sewage, raw sewage, from our bathrooms going into the river remain.

AMNA NAWAZ: So the pipeline here, as you mentioned, it serves Washington, D.C., but also Maryland and Virginia counties in both of those neighboring states as well.

When you talk about the cleanup and the testing that's to come, where's the accountability?

Who is responsible for all of that?

HEDRICK BELIN: Ultimately, D.C.

Water, which is a local utility, is the owner of the pipe, but Loudoun County, Fairfax County, Montgomery County all contributors.

AMNA NAWAZ: Virginia and Maryland.

HEDRICK BELIN: So, Virginia and Maryland all contribute.

They also are on the board of D.C.

Water.

Because it is such a spill into a river, the EPA needs to be involved as well.

So we have got local, state and federal entities that, frankly, we think need to display greater leadership, given the situation.

AMNA NAWAZ: Greater leadership at the federal level or at local, state as well?

HEDRICK BELIN: All three.

We're hearing from lots of concerned citizens that they aren't getting answers to what's going on, they don't understand what they should or shouldn't be doing.

And certainly they're concerned about accountability and ultimately action.

I mean, this needs to be fixed.

It needs to be fixed as soon as possible.

And we need to take steps through an independent investigation looking at root causes to make some systemic changes to make sure something like this doesn't happen again, not just here, but certainly in other cities around the country.

AMNA NAWAZ: Given the scale and the scope, is this something local and state governments can handle on their own?

Because we have seen already President Trump really put the blame on local authorities, saying this is a Maryland and Virginia problem, they should fix it.

If the EPA doesn't get involved here, can this be handled?

HEDRICK BELIN: Yes, well, I think we need the EPA because of the multistate nature that you talked about.

They play an important role.

They also play an important role with the Clean Water Act.

But the states and the localities certainly will be the ones that will end up providing a majority of the money, I suspect, in part because there's been a lot of reduction of federal funds being available for these kinds of situations.

AMNA NAWAZ: We have used words like historic and unprecedented.

For context here,are there other comparable spills you have seen in comparable waterways in other parts of the country that you can look at and people can take a timeline away from?

HEDRICK BELIN: Yes, not this kind of thing.

And, again, it's raw sewage.

It's not jet fuel.

It's not some other toxic chemical.

But it does point to nationally this is clearly a wake-up call, because these pipes were put in the 1960s, this pipe.

There's plenty of pipes that were put in, in infrastructure in the '70s, '80s, and '90s.

And what we're seeing is, if you're delaying the maintenance and investment, you're going to have a failure like this.

So we need -- both for public health, but also for recreational purposes,we need some answers that we can share with the rest of the country to make sure other cities that all have sewage pipes don't experience such a catastrophic failure.

AMNA NAWAZ: Lots of questions still.

We hope there's answers soon.

Hedrick Belin, president of the Potomac Conservancy, thank you for being here.

HEDRICK BELIN: Appreciate it.