[DAVID YETMAN] New Orleans is our nation's party city without serious competitors, but its very existence is regularly threatened by the forces of nature.

Engineers and scientists have responded to the threats in a very big way.

{BLUESY GUITAR} [ANNOUNCER] Funding for In the Americas with David Yetman was provided by Robert and Carol Dorsey, The Gilford Fund, Arch and Laura Brown, and Hugh and Joyce Bell.

[DAVID YETMAN] The Mississippi River is the most important transportation corridor in the United States.

It determines the economic well-being of much of the country.

The southern portion of it, especially around New Orleans, is subject to catastrophic flooding from the river and surge flooding from hurricanes.

The Congress of the United States, along with numerous agencies, have tried to figure out the best way to deal with that, and especially the Army Corps of Engineers have come up with their solutions.

{BLUESY GUITAR} New Orleans faces two huge threats flooding from the river and ocean surges from hurricanes that are inevitable in the region.

The U.S. Congress has designated the Army Corps of Engineers as the agency most responsible for minimizing risk to the city.

Their work has amplified the traditional approach encircling the metropolitan area with a vast levee system, one that will protect the city from the whims of the river and pump out water from the deluges of rain that threaten to flood much of the city.

It is a monumental challenge and there are conflicting opinions as to the overall strategy.

[MARK DAVIS] Where we're standing today in the middle of New Orleans, 2600 years ago was the main channel of the Mississippi River.

About every 1200 years, it finds a new path to the Gulf of Mexico.

We do what we can now to stop that, but there's only so much you can do.

And ultimately, at some point, nature wins, both from where the river goes and where the Gulf goes.

Back in the mid 1980s, when no federal agency and no state agency would even recognize that this coast was collapsing and it was collapsing in large part because we had divorced the rivers that built it from it.

And in 1989, Louisiana amended its laws and constitution to make saving this coast, which means this river, a priority--a funded one.

This is a civics undertaking.

And right now the only reason we have plans and programs that give us a chance of adapting for this coast is because people cared enough to make it a personal responsibility.

{BLUES MUSIC SWELLS} I'm walking on top of the levee that protects the city of New Orleans, the gateway to the Mississippi River, and for hundreds of years, the most important port in the southern part of the United States and for North America.

First by native peoples, then next by Spaniards, French and ultimately the United States.

The river has been channeled, dredged, shaped because of the needs of transportation.

This is the most important transportation route in the entire United States.

And the city of New Orleans benefits from much of that commerce.

But it also pays the price in terms of flooding and hurricanes.

{GUITAR INTENSIFIES} [RICKY BOYETT] When you're looking at the importance of the Mississippi, what it is, is it is that connection between the heartland and the global economy.

Everything that is coming out of your Iowas and your Missouris all of those produce, it's all making its way down to the New Orleans area where it is in transitioned over to ships and gone out throughout the world.

We have the upper river and the lower river and lower river really beginning around Baton Rouge.

And that goes all the way to the Gulf of Mexico and Louisiana.

That's deep draft traffic.

What that means is we keep the river to a minimum of 50 feet deep, and that allows the Panamax size ships to come into the river.

When you look at above Baton Rouge, up to Saint Louis, those are shallow drive traffic.

And that means that it's barge traffic ships can't go.

{CAR DRIVING NOISE} We have over 1100 people that work for the New Orleans district.

We also, as you can see, we have a very much a working dock to bring the ships in.

We're able to help other districts out when they're working in the area.

It's flood control, navigation, recreation, coastal restoration.

You know, when you're the water management agency in an area that's 90% water, you're involved in most things.

[DAVID] It seems a little weird to have a seawall here.

[RICKY] We consider it a hybrid invisible flood wall.

Invisible because 99% of the year, you don't need it and so you don't have to see it.

But once the river starts to rise and we need to stop the water from being able to get this far, we can come in, put the pylons in place.

[DAVID] You pull that plate off and you can screw other things down?

[RICKY] That's exactly right.

There's really two entities or agencies that work together for your primary enforcement of the waterways, the Corps of Engineers.

We're about safe and reliable navigation.

The Mississippi River and Tributaries Project is the most successful project we have in the Corps.

For every dollar we spend, we avoid about $350 in damage.

Then, also we have the US Coast Guard, and they do the more policing and regulation of the vessels as they're coming in and out.

So the Mississippi River is the third largest basin in the world.

The bottom of the river is below sea level for about 220 miles north.

Two and a half million people in Louisiana alone live within the floodplain of the Mississippi River.

We also have the busiest inland waterway in terms of commercial use.

Congress is looking to find the very answer of how do you create a sustainable, a reliable, a resilient Mississippi River for the next 150 years?

It's a five year study to look at flood risk management, to look at navigation, and to look at coastal restoration, as well as hydropower, as well as recreation.

There are all these different facets that we have to understand.

[MARK] I mean, New Orleans is here for one reason and one reason only, and that's because of its relationship to the Mississippi River and the relationship of that river to the Gulf of Mexico.

It was never an easy place, but it was an essential place.

And I want to be real clear.

It was not below sea level.

We made it below sea level by pumping and draining and walling off the waters that built the land.

The key thing to remember is that rivers are far more than just ribbons of water.

They are sculptures.

They make land.

They create environments that allow cultures and human and otherwise to exist.

But none of it lasts for terribly long.

{GUITAR CONCLUDES, BRASS BAND PLAYS} [DAVID] The entire history of New Orleans has deep roots in numerous cultures, more than any other city in the United States.

{PLAYING “WHEN THE SAINTS GO MARCHING IN”} There is the Spanish influence, because this is part of Spain, even more, there is that Cajun influence.

The Cajuns were from Arcadia in what is now Canada.

They were French speakers who fled Canada when the British conquered it, and the Treaty of Paris turned it over to England.

There are creoles who came mostly from Haiti.

Then the settlers from the U.S. brought with them slaves from Africa.

Thousands upon thousands of slaves came in through the port of New Orleans to do all the work to build this empire.

And today, all their institutions retain their flavor and still make New Orleans the true mixing melting pot of the United States in a very good way.

{TRUMPET, DRUMS PLAYING} I'm leaning here on top of the pre- Katrina levee.

This is where water washed over with a storm surge and flooded New Orleans.

Over here is the post-Katrina wall or a levee which is substantially higher.

And the Army Corps of Engineers convinced that any foreseeable hurricane now would not be able to breach this and New Orleans would still be protected.

[RICKY] So the surge barrier is the longest linear surge barrier in the world.

And you have 1.8 miles.

It's a 25 feet above sea level.

But it's an iceberg is what you can see from the water.

It goes directly deep, 140 foot deep, as I liken it, to a medieval city where we built a perimeter wall around New Orleans.

But you have to let people and trains and boats in and out on a daily basis.

And then when a storm is coming, just like that medieval city, if the barbarians at the gate will close everything up, in this case, the barbarians are the water.

[DAVID] New Orleans has always been subject to flooding, even when the first native peoples came here, hundreds, if not thousands of years ago, floods were part of the Mississippi River█s way of operating.

But as it became a vital international port, the flooding danger increased.

In 2005, we found out that the real power of flooding with Hurricane Katrina, who overcame all of the supposedly sophisticated flood control or hurricane proof measures and produced the greatest loss of life and economics in the history of any storm in the United States.

The result was a massive program to build a more or less hurricane impenetrable wall around the city of New Orleans.

And as the water is pouring in here, they will stay here.

Then, when they're dangerous past, the floodgates will open and it will drain back into the main water course.

[RICKY] We are crossing that third busiest in the waterway in the country.

And barge traffic goes in and out all day long.

So we have to have an avenue where they can travel unimpeded.

But then when the storm is coming, we close it over.

{JOYFUL MELODY} If you were to ask me, “what is the greatest single lesson learned from Hurricane Katrina?” That lesson is you can't eliminate risk.

And you can build build structures and you can do other things to further buy down that risk.

But we live in New Orleans.

Hurricanes and large storms are inherent to our area.

There will always be residual risk.

This system was not built to protect people.

It was to reduce the risk to infrastructure and property.

Let the lives leave, we█ll defend the property.

They can come back after the storm is over.

We've had over 106 countries visit the different sites to learn managing hurricane risk with the nation's most important waterway running through the middle.

When we were looking at each project, we had to understand what impacts of crossing this body of water would have on the marshland.

[DAVID] The New Orleans area is the wettest city in the continental United States, 60 inches or more a year average, which means there is a lot of water and the warm climate means that plants grow very fast and trees that are acclimated to this area grow even faster.

Very close to the highway, not far from the shore of Lake Pontchartrain, The Army Corps has helped restore a small forest and wetland that was torn out by previous hurricanes.

They did so because that kind of forest is a natural barrier against surge from a hurricane.

It absorbs huge amounts of energy when the waves hit here and this ancient oak was toppled, probably ten years ago.

It is still living, but it's certainly its survival is compromised.

That was the boardwalk just picked up and flopped over by the hurricane.

It's not real easy walking through this swampy wetlands, but it's worth it just to see this, not ancient, but quite old, bald cypress.

They are very powerful, thick, strong, bold trees.

Their wood very dense.

These are being planted throughout the area because they are the best single defense against storm surge.

{BLUESY GUITAR} So this is the actual levee protecting the city?

[RICKY] This is.

This is the, what we would consider the front line of risk reduction.

It's 16 feet above sea level.

Sometimes the populated areas are right up to the water's edge.

And so we have much closer proximity to homes and businesses.

[DAVID] This roadway, you say, is one of the, what, hundreds of openings in the levee system.

And this will not be open if there's a flood surge.

[RICKY] That's right.

We have 500 openings, not only waterways, but that's railroads and roadways.

And when this storm is approaching, those are gaps in the system.

So we need to close it out.

We have swing gates at this location.

[DAVID] So this is on hinges here?

[RICKY] It is on hinges and, what the levee district will do is, they'll pull the barriers, they'll close this side.

There's one on the other side.

It close together.

And when they lock, then you're completing the system that's going from the lakefront levee to the Outflood canal floodwall.

A weather person in the area once told me, it's like catapulting refrigerators against the wall.

And that's what these have to withstand for 12, 24 hours.

[DAVID] You gotta get the water that█s trapped inside the levee out on the levee.

[RICKY] And so we have to pump around that closures.

{BLUESY GUITAR CONTINUES} [DAVID] You haven't really been to New Orleans until you've tried crawfish {SCOOPING SOUNDS} and this is the best crawfish you can possibly get.

It is good.

[RESTAURANT OWNER] Well, we have onions and lemons, I guess the lemons cook down and they have spices and they boil them and then they have to let them go for about 20 minutes to absorb the flavor.

[DAVID] I see.

[OWNER] And then we pull them out and serve them.

You pull the head off like this.

And if you're from here, this is what you do.

{CRUNCHES} Somewhat.

{LAUGHS} [DAVID] It takes practice.

This is addicting.

[OWNER] It█s very good.

{MUSIC ENDS} {BIRD CHIRPS} [DAVID] The Bonnet Carré Spillway diversion structure was created 90 years ago in order to protect the flood level in New Orleans way downstream.

So if the flood level gets too high, they can open it here.

The water will flow into Lake Pontchartrain and bypass New Orleans.

It has only happened 15 times in its 90 year history.

[JOHN FOGERTY] The structure itself, the steel structure, the timber, needles and the concrete itself is all as was designed and constructed back in the 1930.

Bonnet Carré is designed so that when the flood levels reach a certain point, then we can operate the structure and all the areas downstream across the New Orleans area.

We can maintain the flood level on those levees for a safety factor.

The timber needles are the only other feature that's part of the structure.

When water levels rise, there is some seepage between the gaps in the needles, but that's part of the design to allow that water to flow through.

Then, once we get into a flood stage, we'll pull those needles, lay them horizontal, open all 20 of them up and let that water flow through that bay.

[DAVID] For a 90 year old structure, this is still mighty interesting.

The difference between the two sides really shows what the structure does.

I mean, here is basically a lake, water situation.

And below we have marsh.

But when a lot seeps through they get different conditions below.

And one of them is that water gets deep enough for a fish that's locally viewed as a trash fish called “shag.” {MEN TALKING} The view up here shows you the real economic function of the Mississippi.

First of all, the size of the petrochemical complexes is beyond most people's imagination, including mine.

And the overall effects of that on the environment are hard to overestimate.

But at the same time, this is a primary transportation route in the United States, one of the key transportation words for the U.S. economy.

When you stand on top of the levees, you begin to understand how much the US government has invested in protecting New Orleans.

But perhaps equally important, how much they have spent.

Protect in the industrial complexes that we see here.

[JOHN] It's a it's a very impressive, simple structure.

It serves a great purpose.

And for the construction cost, it█s providing tremendous benefit to the community and as flood risk reduction opportunities.

[NICHOLAS CALI] So we're at the West closure complex.

This is the largest drainage pump station in the world.

This is part of the $14.7 billion that the federal government invested after Hurricane Katrina in south Louisiana.

This structure maintains the safe water elevation on the Harvey and Algiers Canal basin prevent storm surge from intruding into the populated portions of the parish.

The sector gate that you see closing behind me is the thing that prevents storm surge from intruding in.

So now we only have to deal with the rainfall.

The rainfall was removed from the neighborhoods by the pump stations and then removed from this outfall basin by this structure.

So what we're seeing right now is largest sector gate in the Western hemisphere.

[DAVID] The Mississippi River runs north and south.

The inland coastal waterway runs east and west.

But both of those places give access to enormous amounts of water that might not be wanted.

This lock allows those waters to be pumped out or in, depending on the circumstances.

{METAL KNOCKS} [NICHOLAS] So we're going inside the structure all the way down to the belly of the beast.

[DAVID] So we have pump after pump after pump.

[NICHOLAS] Yes.

Each one of these pumps is going to burn 250 gallons of diesel, her engine per hour.

[DAVID] One of these would be a massive pump station?

[NICHOLAS] One of these would be a typical municipal drainage station.

So we're going into the control room now, into of the brains of the operation.

Right here is where we can monitor all of the pump stations that are upstream from us that are feeding into that Harvey and Algiers Canal basin.

But for Hurricane Ida, this thing was completely green.

So we have 24 pan tilt zoom cameras throughout the structure.

So we have eyes on everything inside and outside of the structure.

[DAVID] Sophisticated as the entire operation is, it█s still nice for them to be able to watch the Weather Channel and see what's happening in the tropical Atlantic.

[NICHOLAS] This is as close as you're going to be able to get to the actual operation.

Now, without getting wet, let's say it.

[DAVID] This is where the water comes out?

[NICHOLAS] Right.

These are the discharge chambers.

And so 11 discharge chambers for 11 pumps is a very simple design, but nobody's made it this big before.

[DAVID] This is the largest pumping station in the world.

And just imagine that a huge hurricane has come over New Orleans and stopped, and kept raining and raining.

This water is going to be coming through the pumps to protect the people from New Orleans, from flooding, from that hurricane.

[NICHOLAS] But it's important to remember, it's one piece of a larger system.

It's one piece of the $14.7 billion investment the federal government made in New Orleans.

[DAVID] And that is protecting a huge amount of human life, investments, infrastructure, vital to the operation of the U.S. economy.

[NICHOLAS] Absolutely.

[MARK DAVIS] The river you walk up on the levees and see is a river that is so constrained that it's divorced from the floodplain that it built when in fact, that floodplain is very much a part of the river.

When you look at a map of Louisiana, southern third of it was built by rivers.

And those are rivers that are very dynamic.

They don't like being hemmed in.

And the first thing we did as Europeans, we came over here and we started throwing up walls and we got so good at protecting ourselves from water, we made ourselves vulnerable to water in order to allow commerce, ships, troops, business to take place, we misunderstood the river.

We thought it was something to be controlled.

Not only were we wrong about the river, we were wrong about the wetlands that they built.

You know, not only not wastelands, they're priceless.

Our ability to live here is going to be dependent upon reintroducing ourselves to the system that built our home.

First thing you have to do is understand how rivers and deltas work.

And this is the biggest one on this continent.

When I think about Louisiana, why people should care.

It's not because of the culture, not because the music, not because of the food.

The problems that Louisiana has been facing, they're going to be experiencing it in many places around the world.

And how you accommodate things like navigation, national defense, population centers, cultural treasures.

It won't solve itself.

And all coastal areas have cities that were built on the edge of land and water for good reasons.

And some of those are thousands of years old and some of them are gone.

I think the lesson we have to teach and why everyone should be a New Orleanian somewhere in their heart is because the capacity for change and the capacity for melding science, law, culture and economics is in the laboratory here.

I don't know how it turns out for us.

Whatever comes out of this place is going to be important to others.

[DAVID] When we see the few idyllic places left where we can see what the Mississippi River in its delta were, it brings back the memory of what a resource we have and this most important waterway, this most important transportation corridor, this economic artery of North America, can be brought back into the perspective of what nature can do to help us retain a water resource that we have to have but will not have unless we listen very carefully to what nature has to tell us.

Join us next time In the Americas with me, David Yetman.

Baja California is a skinny peninsula, 750 miles long and less than 200 miles wide.

Most of it is very dry desert, but on its eastern flank is the Gulf of California.

Where the desert meets the sea, is one of the world's most productive marine waters and an aquatic abundance unmatched anywhere.

{UNDERWATER SOUNDS} {SHORE BIRDS} {PLAYING “SUMMERTIME” BY ELLA FITZGERALD” [ANNOUNCER] Funding for In the Americas with David Yetman was provided by Robert and Carol Dorsey, The Gilford Fund, Arch and Laura Brown, and Hugh and Joyce Bell.