NARRATOR: THE MOODY, MUDDY MISSISSIPPI... [BOAT WHISTLES] THE HEART AND SOUL OF THE DEEP SOUTH.

THIS FACE OF THE MISSISSIPPI IS KNOWN THE WORLD OVER... INSPIRATION FOR WRITERS AND MUSICIANS.

BUT THESE FAMILIAR SWAMPS ARE ONLY A TINY PART OF A MUCH BIGGER STORY.

THE MISSISSIPPI STRETCHES OUT ACROSS 31 STATES.

FROM SURPRISING BEGINNINGS IN THE FROZEN NORTH... ITS ARTERIES JOURNEY ALL THE WAY ACROSS THE U.S...

RIGHT DOWN TO THE STEAMY SOUTH, CONNECTING AND UNITING A GREAT CONTINENT.

AN ICONIC RIVER THAT LIES AT THE HEART OF THE AMERICAN STORY.

E PLURIBUS UNUM, OUT OF MANY, ONE...

THE FOUNDING PRINCIPLE OF THE UNITED STATES AND THE VERY SOUL OF THE MISSISSIPPI.

EARTH'S RIVERS OF LIFE MAKE EXTRAORDINARY JOURNEYS, CARVING THROUGH CONTINENTS, NURTURING GREAT CIVILIZATIONS, FEEDING AND CONNECTING LIFE ACROSS OUR WORLD.

[ELEPHANT GRUNTS] THESE RIVERS ARE THE LIFE-BLOOD OF PLANET EARTH.

NARRATOR: THE MISSISSIPPI'S UPPER HEADWATERS HAVE EXTRAORDINARY BEGINNINGS.

THEY GATHER WATER FROM ACROSS A STRETCH OF THE NORTHERN UNITED STATES 1,500 MILES WIDE.

THE MISSISSIPPI'S LONGEST TRIBUTARY IS THE MISSOURI, WHICH STARTS HERE IN THE NORTHWEST AMONG THE TOWERING ROCKIES, MORE THAN 3,5000 MILES UPSTREAM FROM WHERE THE RIVER WILL FINALLY MEET THE SEA.

WINTER HERE CAN LAST FOR 5 MONTHS, AND RIGHT NOW BILLIONS OF TONS OF WATER DESTINED FOR THE MISSISSIPPI ARE TRAPPED AS ICE AND SNOW.

IN SUMMER, THIS IS A FAST-FLOWING TORRENT.

BUT FOR NOW, ANIMALS WHO DEPEND ON IT, LIKE THESE OTTERS, ARE FORCED TO SEARCH FOR HOLES IN THE ICE TO ALLOW THEM TO FISH.

BUT SOME CHOOSE TO COME HERE TO TACKLE THE FROZEN HEADWATERS OF THE MISSISSIPPI HEAD ON.

FOR SOME CLIMBERS, THERE IS NO GREATER CHALLENGE THAN SCALING A SHEER WALL OF ICE.

MAN: YOU'RE BASICALLY CHASING A HIDDEN TREASURE... THAT SOMEBODY TOLD YOU WAS UP IN THE HILLS.

AND EVERY ONCE IN A WHILE, YOU ACTUALLY GET TO FIND IT.

NARRATOR: FOR AARON MULKEY, ONE OF THE MOST EXPERIENCED ICE CLIMBERS IN THE WORLD, WINTER IS HIS FAVORITE TIME OF YEAR.

HERE, THE MISSISSIPPI IS SUSPENDED IN THE FORM OF TOWERING, FROZEN WATERFALLS.

[BIRD SCREECHES] THESE PROVIDE SOME OF THE BEST ICE CLIMBING IN THE U.S. MULKEY: I DON'T THINK PEOPLE EVER REALLY IMAGINED THESE THINGS WOULD EVER FREEZE.

100, 200-FOOT, MASSIVE, JUST SPECTACULAR CHUNK OF ICE.

AND IT'S SORT OF CRAZY TO THINK THAT, YOU KNOW, WHEN YOU'RE CHOPPING AWAY, ICE CLIMBING UP THESE THINGS, THAT THAT WATER MAY END UP IN THE GULF OF MEXICO AT SOME POINT.

NARRATOR: EVERY ONE OF THESE FROZEN WATERFALLS IS UNIQUE.

THEY NEVER FORM THE SAME WAY TWICE.

MULKEY: THESE WATERFALLS ARE VERY MUCH ALIVE.

YOU KNOW, YOU'RE WATCHING THEM WITH A LITTLE TRICKLE OF WATER.

THEY'RE CONSTANTLY MOVING AND SHIFTING.

[ICE CRACKING] YOU CAN HEAR THE ICE CRACK AND SOMETIMES SHIFT.

SOME OF THOSE NOISES ARE OK.

SOME OF THEM ARE MUCH MORE CONCERNING.

[ICE CRACKING] ICE!

MULKEY: ICE CLIMBING IS PRETTY UNIQUE.

YOU KNOW, IF YOU GO ROCK CLIMBING, IT'S THERE, IT'S ALWAYS GOING TO BE THERE, BUT ICE IS THERE ONE DAY AND GONE TOMORROW.

NARRATOR: THESE FROZEN WATERFALLS ARE THE MOST DRAMATIC WINTER FACES OF THE MISSISSIPPI.

BUT JUST A FEW VALLEYS AWAY IS SURELY ONE OF THE MOST SURPRISING.

NO MATTER HOW COLD IT GETS, ONE REMOTE MISSISSIPPI TRIBUTARY THROWS THE LOCAL WILDLIFE A LIFELINE.

IT BEGINS IN YELLOWSTONE NATIONAL PARK, WYOMING... WHERE STEAMING GEYSERS SPEW OUT BOILING WATER...

INTO THE MIDDLE OF THIS ICE-BOUND WILDERNESS.

THIS KEEPS PRECIOUS STREAMS LIKE THE MADISON RIVER FLOWING THROUGH THE ICE AND SNOW.

DESPITE THE AIR SOMETIMES DROPPING TO 40 BELOW, THIS RIVER NEVER FREEZES OVER.

[RACCOON CHITTERING] WINTER IS ESPECIALLY HARD FOR YELLOWSTONE'S COYOTES, ENDLESSLY SEARCHING FOR SOMETHING TO EAT.

BUT A FEW HAVE LEARNED THAT THIS PARTICULAR RIVER HOLDS A POTENTIAL MEAL.

FISHING DOESN'T COME NATURALLY TO COYOTES.

THIS FEMALE, HOWEVER, HAS EXTRAORDINARY PERSISTENCE.

THE WETTER SHE GETS, THE GREATER THE RISK OF HYPOTHERMIA.

♪ BUT AFTER 4 HOURS ENDURING THE BITTER COLD AND CATCHING NOTHING...

FINALLY A TWO-FOOT RAINBOW TROUT.

THIS TENACIOUS INDIVIDUAL IS ONE OF THE ONLY COYOTES IN THE WORLD WHO HAS LEARNED TO FISH THIS WAY, THANKS TO THE UNUSUAL LIFELINE THE MADISON RIVER PROVIDES.

800 MILES TO THE EAST, ONE FROZEN LAKE IN MINNESOTA IS A STAR ATTRACTION.

HERE, THE DEEP FREEZE OF THE UPPER MISSISSIPPI IS CELEBRATED ON A MASSIVE SCALE.

[DRILL WHIRRING] EVERY JANUARY ON GULL LAKE...

TEAMS OF PEOPLE DRILL OVER 20,000 HOLES THROUGH ICE UP TO TWO FEET THICK.

THE FOLLOWING DAY OVER 11,000 PEOPLE COME HERE FROM ACROSS THE COUNTRY TO COMPETE IN THE WORLD'S LARGEST CHARITY ICE FISHING CONTEST.

IT HAS BEEN RUNNING FOR NEARLY 3 DECADES, AND DESPITE THE COLD, IT'S BECOME A FAMILY TRADITION FOR MANY PEOPLE HERE, LIKE ASHLEY JANSON AND HER FAMILY.

WOMAN: I'M GOING TO CATCH THE BIGGEST FISH TODAY.

PUT YOUR HANDS DOWN, GUYS.

I ALREADY WON.

I WANT TO CATCH IT.

WHEN YOU LIVE IN THIS BRUTAL, COLD WEATHER, IT'S TOTALLY IN YOUR BLOOD.

IT'S SOMETHING YOU HAVE TO DO.

THIS IS THE REAL EXPERIENCE, YOU KNOW?

MAN: I MEAN, IT IS A FAMILY TRADITION OUT HERE.

THERE ARE A LOT OF FAMILIES THAT COME OUT HERE AND FISH, BRING THEIR KIDS.

WOMAN: I'VE BEEN COMING PROBABLY 7 YEARS.

I'VE BEEN COMING A WHILE.

YEAH.

I JUST LOVE BEING IN A BIG GROUP AND JUST CHEERING PEOPLE ON AND SEEING WHAT PEOPLE CAN CATCH, BECAUSE THERE ARE SO MANY DIFFERENT VARIETIES OF FISH, AND IT'S JUST FUN BECAUSE YOU NEVER KNOW WHAT YOU'RE GOING TO GET, OR IF YOU'RE GOING TO GET ANYTHING, SO I JUST LOVE THE THRILL OF IT, NOT KNOWING.

MAN ON SPEAKER: ♪ LAND OF THE FREE ♪ ♪ AND THE HOME OF THE BRAVE ♪ [CHEERING AND APPLAUSE] ANNOUNCER: LADIES AND GENTLEMEN, WELCOME TO THE BRAINERD JAYCEE'S ICE FISHING EXTRAVAGANZA.

NARRATOR: THE COMPETITORS HAVE JUST 3 HOURS TO CATCH AND RELEASE THE LARGEST FISH THEY CAN.

MAN: WHEN YOU GOT 14,000 OTHER PEOPLE YOU'RE FISHING AGAINST, YOU KNOW, IF YOU CAN PULL A FISH IN, THAT'S A BIG FEATHER IN YOUR HAT.

NARRATOR: BUT NO MATTER HOW CONFIDENT AND EXPERIENCED, NOT EVERYONE GOES HOME WITH A PRIZE, OR EVEN A BITE.

MAN: WE DIDN'T CATCH ANYTHING TODAY.

SHE DIDN'T CATCH NOTHING, I DIDN'T CATCH NOTHING.

WOMAN: YOU KNOW, IT'S A CHARITY EVENT, SO I MEAN, EVEN IF WE DON'T CATCH ANYTHING, JUST THE EXPERIENCE ALONE IS WORTH IT, AND SEEING ALL THESE PEOPLE FROM ALL OVER THE COUNTRY IS AMAZING.

YEAH, IT'S JUST NICE KNOWING THAT THE MONEY GOES TO GOOD.

NARRATOR: EVEN THE FROZEN OUTER REACHES OF THE MISSISSIPPI CAN BRING PEOPLE TOGETHER.

BUT THE ICE WON'T LAST LONG.

STARTING IN MID-APRIL, ALL ACROSS THE FROZEN NORTH, THE SEASON CHANGES.

SLOWLY, THE TEMPERATURES RISE AND THE THAW BEGINS.

IN THE MOUNTAINS, THE SPRING MELT SOMETIMES DOESN'T HAPPEN UNTIL AS LATE AS JUNE.

THE SLEEPING GIANT OF THE MISSISSIPPI IS FINALLY UNLEASHED.

♪ BILLIONS OF GALLONS OF WATER ARE ON THE MOVE.

THEY CARVE OUT ROCKY VALLEYS, COLLECTING SEDIMENT FROM ACROSS THE COUNTRY.

THEY CAN CONSUME EVERYTHING IN THEIR PATH.

♪ THIS DRAMATIC TRANSFORMATION MARKS THE ANNUAL AWAKENING OF LIFE ACROSS THE MISSISSIPPI.

NOWHERE IS THIS MORE TRUE THAN IN THE APPALACHIAN MOUNTAINS, 1,500 MILES EAST OF THE ROCKIES.

♪ HERE IN TENNESSEE AND VIRGINIA, THE MISSISSIPPI'S UPLAND STREAMS ARE A HAVEN FOR AN INCREDIBLE VARIETY OF LIFE... HELLBENDERS, A RARE SPECIES OF SALAMANDER, THAT CAN GROW TO OVER TWO FEET LONG.

HUGE SHOALS OF FISH, LIKE THESE BUFFALO SUCKERS, MASS TO SPAWN.

WHILE ON THE RIVERBEDS, CHUB BUILD STONY NESTS TO PROTECT THEIR EGGS.

♪ BUT ONE GROUP OF MISSISSIPPI RIVER ANIMALS HAS COME UP WITH AN ASTONISHING WAY OF GIVING THEIR YOUNG THE BEST POSSIBLE START IN LIFE... FRESHWATER MUSSELS.

DURING THE BREEDING SEASON, PART OF THE MANTLE WHICH RUNS ALONG THE EDGES OF THEIR SHELL CHANGES SHAPE.

IT BEGINS TO RESEMBLE A SMALL FISH SWIMMING IN THE CURRENT.

A SMALL FISH THAT LARGER FISH MIGHT WANT TO EAT.

HIDDEN INSIDE THESE LURES ARE SACKS CONTAINING THOUSANDS OF TINY MUSSEL LARVAE.

TO DISPERSE AND FIND A NEW HOME, THE LARVAE NEED TO LATCH ONTO THE GILLS OF A LARGE FISH.

FOR THIS TO HAPPEN, THE ADULT MUSSELS NEED TO FOOL A FISH INTO BITING THEIR LURE.

♪ THE LARVAE CLAMP ON AND BEGIN TO SUCK NUTRIENTS FROM THE FISH'S BLOOD.

THEY HITCH A RIDE ON THE FISH'S GILLS FOR A FEW WEEKS, BEFORE FINALLY DROPPING OFF.

BY BITING INTO THE INGENIOUS LURES, THE FISH UNWITTINGLY SPREAD YOUNG MUSSELS UP AND DOWN THE RIVER, SURELY ONE OF THE MOST EXTRAORDINARY PARENTING STRATEGIES ON EARTH.

FOR MOST RIVER CREATURES, THE SURGING WATERS OF SPRING ARE WHAT THEY HAVE BEEN WAITING FOR.

BUT FOR ONE ICONIC MISSISSIPPI RESIDENT, THE SPRING MELT IS NOT SO WELCOME.

BEAVERS ARE FOUND THROUGHOUT THE MISSISSIPPI BASIN.

THEY BUILD DAMS TO CREATE A WATERY MOAT AROUND THEIR HOMES, WHICH PROTECTS THEM FROM PREDATORS THAT COULD ATTACK FROM THE LAND.

INSIDE THEIR HOMES, KNOWN AS LODGES, ADULTS AND THEIR KITS ARE SAFE AND WARM.

[KITS SQUEAKING] BUT THEIR PEACE IS ABOUT TO BE BROKEN.

[RUSHING WATER] THE BEAVERS CAN HEAR THERE IS A PROBLEM.

RESEARCHERS HAVE FOUND THAT THE SOUND OF RUNNING WATER IS SOMETHING THAT BEAVERS ARE SIMPLY UNABLE TO IGNORE.

THE SOUND MEANS THEIR PRECIOUS DAMS ARE IN DANGER OF BEING SWEPT AWAY BY THE SWELLING STREAMS... LEAVING THEIR LODGES EXPOSED.

FOR THEIR OWN SAFETY, THEY HAVE TO REPAIR THE DAMAGE THE FLOODING HAS DONE.

♪ THE BEAVERS MUST GNAW, DRAG, AND PACK AS MUCH MATERIAL INTO THE DAMS AS THEY CAN TO TRY AND STAUNCH THE FLOW.

♪ IT'S AN ENDLESS TASK.

BEAVERS SPEND THEIR WHOLE LIVES TRYING TO BLOCK THE RIVER, BUT THE SWOLLEN WATERS OF THE MISSISSIPPI CAN'T BE HELD BACK.

♪ HUMANS HAVE ALSO TRIED TO CONTROL THE POWERFUL WATERS OF THE MISSISSIPPI'S TRIBUTARIES.

THEY TOO HAVE BUILT DAMS, LIKE THESE IN THE FOOTHILLS OF THE ROCKIES.

MANY ARE USED TO STORE MELT WATER FOR IRRIGATION IN THE DRY SUMMER MONTHS.

BUT NOT EVEN THESE MIGHTY, 300-FOOT-HIGH WALLS CAN ENTIRELY CONTAIN THE MISSISSIPPI ON ITS JOURNEY DOWNSTREAM.

♪ ON MARSH LAKE IN WESTERN MINNESOTA, HUMAN DAMS HAVE HAD A SURPRISING EFFECT ON MISSISSIPPI WILDLIFE.

HERE, A MAN-MADE DAM KEEPS THE LAKE'S LEVEL HIGH.

THIS HAS CREATED THE PERFECT BREEDING SANCTUARY FOR ONE OF THE LARGEST WATER BIRDS ON THE CONTINENT... AMERICAN WHITE PELICANS.

THEY ARRIVE HERE EACH SPRING ON 9-FOOT WINGSPANS.

SOME OF THEM HAVE FLOWN OVER 2,000 MILES JUST TO GET HERE.

THEIR NESTS ARE PROTECTED FROM PREDATORS BY THE SURROUNDING WATERS.

22,000 OF THEM CRAM ONTO THE ISLANDS.

AS A SIGN THAT THEY'RE READY TO BREED, BOTH MALES AND FEMALES GROW A SPECIAL HORN ON THEIR BILLS...

WHICH DROPS OFF AFTER THEIR EGGS HAVE BEEN LAID.

BUT MARSH LAKE'S DAM OFFERS MORE THAN JUST PROTECTION.

IT FORCES MIGRATING FISH THROUGH A NARROW GAP, CONCENTRATING THEM ALL IN ONE PLACE.

AND PELICANS ARE FAMED FOR THEIR APPETITE.

SOME OF THE CARP FUNNELED ACROSS THE DAM CAN BE OVER 3 FEET LONG.

BUT WHEN ONE PELICAN FINDS MORE SUITABLY-SIZED FISH...

IT'S THE CUE FOR THEM ALL TO PILE IN.

♪ THE FISH DON'T STAND A CHANCE.

THE PELICAN FLOCK OF MARSH LAKE MUST BE ONE OF THE MOST SPECTACULAR WAYS THAT THE UPPER MISSISSIPPI BRINGS WILDLIFE TOGETHER.

AFTER THEIR YOUNG HAVE FLEDGED, THESE PELICANS WILL LEAVE.

THEY'LL FLY TOWARDS THE MAIN CHANNEL OF THE MISSISSIPPI RIVER, USING IT TO HELP NAVIGATE ON THEIR LONG JOURNEY SOUTH.

AS THEY LEAVE ITS WILD UPPER REACHES, THE MISSISSIPPI'S TRIBUTARIES FUNNEL THEIR WATER DOWN TOWARDS THE MAIN RIVER CHANNEL, PASSING INTO AMERICA'S FARMING HEARTLAND, AND YET STILL 2,000 MILES FROM THE RIVER'S MOUTH.

92% OF THE U.S.'s AGRICULTURAL EXPORTS ARE PRODUCED WITHIN THE MISSISSIPPI BASIN.

STATES LIKE IOWA, ILLINOIS, WISCONSIN, GROWING EVERYTHING FROM GRAIN TO SOY TO CRANBERRIES.

WISCONSIN PRODUCES OVER HALF OF THE WORLD'S CRANBERRIES.

HISTORICALLY, THIS INDUSTRY RELIED ON THE MISSISSIPPI'S WATER.

WHEN THE FRUIT IS RIPE, THE FIELDS ARE DELIBERATELY FLOODED.

THE CRANBERRIES FLOAT TO THE TOP... READY TO BE SKIMMED OFF THE SURFACE AND EXPORTED ACROSS THE GLOBE.

THE CENTRAL STRETCH OF THE MISSISSIPPI HELPS FEED THE ENTIRE NATION AND IS A FERTILE HOME FOR WILDLIFE, TOO.

EACH YEAR AROUND INDEPENDENCE DAY, TINY INSECTS PUT ON AN AMAZING SHOW OF THEIR OWN.

MAYFLIES.

THEIR NYMPHS HAVE LIVED ON THE RIVERBED FOR UP TO TWO YEARS, SLOWLY MATURING, PREPARING TO SPROUT WINGS, AND TAKING TO THE AIR TOGETHER.

MILLIONS EMERGE SIMULTANEOUSLY, IN SWARMS SO BIG, THEY CAN BE SEEN ON WEATHER RADAR.

[MAYFLIES FLUTTERING] THE ADULT MAYFLIES HAVE NO WORKING MOUTHPARTS AND ARE UNABLE TO FEED.

THEY EMERGE SIMPLY TO MATE, AFTER WHICH TIME THE FEMALES MUST RETURN TO THE MISSISSIPPI TO LAY THEIR EGGS.

JUST TWO DAYS AFTER THEY APPEARED, THE FINAL SPECTACULAR STAGE OF THEIR LIFE WILL BE OVER.

MAYFLIES HAVE RISEN FROM THE RIVER SINCE LONG BEFORE PEOPLE SETTLED HERE.

[TRAIN WHISTLE BLOWS] BUT THOSE THAT EMERGE TODAY ARE SURROUNDED BY THE MODERN FACE OF THE MISSISSIPPI, TRANSFORMED BY AGRICULTURE AND INDUSTRY.

THIS STRETCH OF RIVER BETWEEN MINNEAPOLIS AND ST. LOUIS IS THE STEEPEST SECTION OF THE MISSISSIPPI.

TO KEEP THE WATERS DEEP ENOUGH FOR SHIPS TO PASS, HUGE LOCKS AND DAMS HAVE BEEN BUILT ACROSS THE CHANNEL.

WHAT WAS ONCE A WILD, RUSHING RIVER HAS BEEN TRANSFORMED BY HUMAN ENGINEERING INTO A HUGE, SLUGGISH CANAL.

TODAY, PEOPLE HAVE TURNED THE MISSISSIPPI INTO AN ARTERY FOR COMMERCE.

HUGE FLEETS OF BOATS MOVE MILLIONS OF TONS OF THE NATION'S PRODUCE UP AND DOWN THE LENGTH OF THE COUNTRY.

THIS HAS GIVEN RISE TO A WHOLE COMMUNITY WHO LIVE AND RELY ON THE MISSISSIPPI, INCLUDING CAPTAIN JOHN HILLGARTNER.

HILLGARTNER: ALL THESE PEOPLE ARE DEPENDENT ON THE RIVER FOR THEIR LIVELIHOOD.

WE ALL HAVE A LIVING, AND IT GIVES US A LIVING.

THE HOURS ARE LONG, THE WORK'S HARD.

WHEN YOU COME BACK, IT'S LIKE YOU'RE COMING BACK TO YOUR HOME.

IT'S JUST A WAY OF LIFE.

NARRATOR: FED BY TRADE ON THE RIVER, BUSTLING CITIES HAVE GROWN UP ALL ALONG ITS BANKS.

HALFWAY DOWN THE MISSISSIPPI, ST. LOUIS WAS BUILT WHERE THE LONGEST OF THE TRIBUTARIES, THE MISSOURI, JOINS THE MAIN CHANNEL.

IT'S BEEN A HUB FOR RIVER TRANSPORTATION FOR OVER 150 YEARS.

GRAIN IS TRUCKED HERE FROM ACROSS THE CENTRAL U.S., DESTINED FOR THE REST OF THE WORLD.

ON THE RIVER, TUGBOAT CAPTAINS CORRAL HUGE, EMPTY BARGES.

EACH ONE CAN CARRY 1,500 TONS OF GRAIN OR SOY BEANS.

ONCE LOADING IS FINISHED, THE BARGES ARE SHUFFLED TOGETHER IN GIANT FLOTILLAS.

EACH ONE CAN COVER THE AREA OF 4 FOOTBALL FIELDS AND BE OVER A THOUSAND FEET LONG.

THE FLOTILLA WILL BE PUSHED DOWNSTREAM BY A SINGLE TUG, AND THANKS TO THE RIVER'S HELP, JUST ONE BOAT CAN HAUL AS MUCH CARGO AS OVER 2,500 TRUCKS.

[SHIP HORN] ♪ A BOAT TRIP DOWN THE MISSISSIPPI IS NEARLY 2,000 MILES AND CAN TAKE UP TO TWO WEEKS.

IT REQUIRES CONCENTRATION, EXPERIENCE, AND NERVE TO STEER THESE GIANTS.

HILLGARTNER: WE WORK OUT HERE ON A NON-STOP OPERATION.

IT GOES 24/7, 365 DAYS A YEAR.

WE WORK 6 HOURS ON, 6 HOURS OFF, FOR A MONTH AT A TIME.

NARRATOR: AFTER DARK, SEARCHLIGHTS GUIDE THE BOATS ALONG THE RIVER.

WITH JUST A FEW FEET TO SPARE, THREADING THE BARGES THROUGH THE LOCKS BECOMES EVEN TRICKIER AT NIGHT.

HILLGARTNER: 5 HOURS AND 59 MINUTES OF SHEER BOREDOM, THEN YOU'VE GOT 60 SECONDS OF SHEER TERROR, BECAUSE YOU COME DOWN ON A BRIDGE OR SOMETHING LIKE THAT AND YOU'RE NOT QUITE SHAPED UP FOR IT, HOPING YOU GET THROUGH YOUR BAD SPOT.

NARRATOR: THE EQUIVALENT OF 49 MILLION TRUCKLOADS OF GOODS ARE TRANSPORTED ON THE MISSISSIPPI EVERY YEAR.

IT'S BECOME A VAST AND HECTIC HIGHWAY, BRINGING CARGO FROM ACROSS THE COUNTRY AND CARRYING IT SOUTH TO THE GULF.

♪ AS THE RIVER REACHES THE LAST THOUSAND MILES OF ITS JOURNEY, ITS CHARACTER CHANGES YET AGAIN.

IT WIDENS, SLOWS, AND BEGINS TO FLOW THROUGH A VAST NATURAL FLOOD PLAIN.

MASSIVE, MEANDERING DETOURS AND SHIFTING SANDBANKS MARK THE BEGINNING OF THE LOWER MISSISSIPPI AS IT ENTERS THE DEEP SOUTH.

RIVER GUIDE JOHN RUSKEY HAS PADDLED THIS ICONIC SECTION OF THE MISSISSIPPI FOR OVER 35 YEARS.

WHEN WE FLOW OUT OF THE CITIES AND CIVILIZATION, THE LAND IMMEDIATELY BECOMES WILD-- THE PLACE WHERE THE BIG WATER MEETS THE BIG FOREST UNDERNEATH THE BIG SKY.

[BIRD CALLS] NARRATOR: BECAUSE THE LANDSCAPE HERE IS SO FLAT, WHEN THE RIVER IS SWOLLEN BY HEAVY RAIN OR SPRING MELT WATER, IT OFTEN FLOODS OUT BEYOND ITS MAIN CHANNEL.

OVER TIME, THIS HAS HELPED TO CREATE A VAST LABYRINTH OF INTERCONNECTED BACKWATERS, LAKES, AND SWAMPS.

RUSKEY: WHEN YOU LEAVE THE MAIN CHANNEL OF THE MISSISSIPPI AND PADDLE INTO THE CYPRESS SWAMPS, IT'S LIKE ENTERING A WHOLE NEW WORLD.

YOU GET THIS FEELING THAT THE RIVER IS GETTING LOST AS IT MEANDERS INTO THE BELLY OF SOME MYSTERIOUS, GIANT WILDERNESS.

NARRATOR: THIS IS THE ATCHAFALAYA, THE LARGEST SWAMP IN THE U.S. OVER A MILLION ACRES, ALL FERTILIZED BY SEDIMENT THE MISSISSIPPI HAS BROUGHT HERE FROM ACROSS THE COUNTRY.

MUCH OF IT IS FLOODED FOREST, HUGE SWAMP CYPRESS TREES DRAPED WITH SPANISH MOSS.

RUSKEY: HISTORICALLY, THE RIVER JUST FLOODED EVERYWHERE ACROSS THIS SOMETIMES 100-MILE-WIDE FLOOD PLAIN, AND ALL THESE NUTRIENTS THAT THE RIVER'S CARRYING FROM THE ROCKY MOUNTAINS TO THE APPALACHIA ARE ALL CONCENTRATED, AND AS A RESULT, THESE HARDWOOD FORESTS BECAME THE RICHEST FORESTS IN NORTH AMERICA.

NARRATOR: HERE IN THE WATER-LOGGED SOUTH, BEAVERS WORRY LESS ABOUT FAST-FLOWING TORRENTS WASHING THEIR DAMS AWAY AND MORE ABOUT PREDATORS HIDING BENEATH THE SURFACE.

THE SWAMPS ARE ALSO HOME TO A VAST ARRAY OF OTHER WILDLIFE.

EGRETS, HERONS... AND ROSEATE SPOONBILLS... WHITE IBIS AND ANOLE LIZARDS.

THE SWAMP IS A HAVEN FOR LIFE.

RUSKEY: IT IS ONE OF THE FEW REMAINING WILD PLACES, AS WILD AS PARTS OF ALASKA OR THE ROCKY MOUNTAINS.

NARRATOR: IN EARLY AUTUMN, THE SWAMP ECHOES TO THE SQUEAKING SOUNDS OF THE YOUNG OF ONE OF ITS MOST FAMOUS AND MOST FEARED PREDATORS.

[SQUEAKING] THESE PERFECTLY CAMOUFLAGED LITTLE REPTILES ARE BABY ALLIGATORS, ONLY RECENTLY HATCHED FROM THEIR EGGS.

DESPITE BEING JUST 6 INCHES LONG, THEY'RE ALREADY EQUIPPED TO TAKE ON ANYTHING THEY CAN GET THEIR JAWS AROUND.

BUT AT THIS SIZE, THEY CAN EASILY BECOME A MEAL THEMSELVES.

[BABY ALLIGATORS SQUEAKING] MANY AROUND HERE WOULD SNAP UP A BABY GATOR, INCLUDING GREAT EGRETS, UP TO 3 FEET TALL.

BUT THE BIRDS MUST KEEP AN EYE OUT FOR MOM.

9 FEET LONG, SHE LIES IN WAIT, LISTENING TO HER BABIES' SQUEAKS, READY TO ATTACK ANYTHING THAT COMES TOO CLOSE.

THE YOUNGSTERS CAN BASK SAFE UNDER HER PROTECTIVE GAZE.

BUT LURKING DEEPER IN THESE SWAMPS IS ANOTHER PREDATOR THAT IS EVEN MORE TERRITORIAL.

THEY HAVE EVEN BEEN KNOWN TO LOSE LIMBS AND YET STILL CONTINUE TO FIGHT.

♪ SWAMP CRAWFISH.

THEY MAY ONLY BE A FEW INCHES LONG, BUT POUND FOR POUND, THEY'RE JUST AS FORMIDABLE AS AN ALLIGATOR... AND WILL FIERCELY DEFEND THEIR TERRITORY.

♪ IF A FLASH OF THEIR PINCERS DOESN'T SCARE OFF A WOULD-BE TRESPASSER, IT'S TIME FOR A SHOW-DOWN.

♪ ONCE THE DISPUTE HAS BEEN SETTLED, THE LOSERS MAKE A HASTY RETREAT, LEAVING THE VICTOR TO MUNCH ON THE SPOILS.

THE HUGE SWAMP FORESTS ARE ABLE TO SUPPORT SUCH AN ABUNDANCE OF LIFE BECAUSE THEY HAVE BEEN NOURISHED OVER THOUSANDS OF YEARS BY THE ANNUAL FLOODING OF THE MISSISSIPPI RIVER.

THE ATCHAFALAYA IS A SURVIVING FRAGMENT OF A MUCH LARGER NETWORK OF MISSISSIPPI SWAMPS WHICH WERE ONCE 5 TIMES LARGER THAN THEY ARE TODAY.

OVER THE LAST 150 YEARS, MUCH OF THE FERTILE FLOODPLAIN HAS BEEN CLEARED AND DRAINED TO MAKE WAY FOR FARMS AND CITIES.

[SHIP HORNS HONK] NEW ORLEANS, THE FINAL BIG CITY BEFORE THE RIVER MEETS THE SEA.

ORIGINALLY ALL THIS WAS SWAMP, AND TODAY PARTS OF THE CITY ARE 25 FEET BELOW THE RIVER'S HIGHEST WATER LEVEL.

IT'S BECOME A NEVER-ENDING BATTLE TO HOLD THE RIVER BACK AND PREVENT ITS NATURAL CYCLE OF FLOODING.

1,600 MILES OF LEVEES AND WALLS HAVE BEEN CONSTRUCTED, HEMMING IN 80% OF THE LOWER MISSISSIPPI.

YET THE FLOOD DEFENSES HAVE BEEN REPEATEDLY BREACHED BY THE STUBBORN RIVER.

EACH TIME, THE BARRIERS HAVE BEEN REBUILT TALLER AND STRONGER.

AND WHERE THE WATER CAN'T BE HELD BACK, PEOPLE HAVE SIMPLY BUILT OVER THE TOP OF IT.

THE 3 LONGEST BRIDGES IN THE U.S. HAVE BEEN CONSTRUCTED ABOVE THESE MISSISSIPPI WETLANDS.

THE BIGGEST IS LAKE PONTCHARTRAIN CAUSEWAY, NEARLY 24 MILES LONG.

IT LEADS ACROSS A VAST SWAMPY LAGOON INTO THE CENTER OF NEW ORLEANS.

ALONG THE RIVER HERE, A 60-MILE STRETCH HAS BEEN TURNED INTO THE LARGEST PORT IN THE WESTERN HEMISPHERE.

♪ THE CARGO CARRIED ON THE BARGES IS TRANSFERRED TO HUGE OCEAN-GOING SHIPS.

THE MASSIVE VESSELS STEAM THEIR WAY THROUGH THE FINAL HUNDRED MILES OF WETLANDS, ON THEIR WAY OUT TO SEA AND AROUND THE WORLD.

THIS IS THE LAST STAGE OF THE MISSISSIPPI'S LONG JOURNEY... A MARSHY DELTA OF ISLANDS, CHANNELS, AND BEACHES WHICH FORM THE FINAL BOUNDARY BETWEEN THE LAND AND THE OCEAN.

IT COVERS AN AREA OF OVER 7 MILLION ACRES.

IT'S A RICH FISHING GROUND, A DRAW FOR BOTH PEOPLE AND WILDLIFE.

[BIRDS CHIRPING] WHITE PELICANS, MANY THE SAME INDIVIDUALS THAT BRED AT THE OTHER END OF THE MISSISSIPPI, HAVE MIGRATED HERE TO TAKE ADVANTAGE OF THE SUBTROPICAL CLIMATE OF THE GULF OF MEXICO.

REDDISH EGRETS, UNIQUE TO THE SOUTH.

ONCE PUSHED TO THE BRINK OF EXTINCTION FOR THEIR CREST FEATHERS, THEY'RE NOW MAKING A COMEBACK.

IN THE MUDDY WATERS, SMALL FISH CAN BE HARD TO SPOT.

WHEN AN EGRET DOES MANAGE TO FIND ONE, IT DOESN'T LET IT OUT OF ITS SIGHT.

♪ IT'S GOT AWAY.

♪ BUT ALL THE RUNNING AROUND WAS WORTH IT.

THANKS TO ITS STATUS AS A PROTECTED SPECIES, THE REDDISH EGRETS' UNIQUE FISHING DANCE CAN NOW BE SEEN ALL ACROSS THESE WETLANDS.

BUT TODAY THEY'RE FACING A NEW THREAT.

THIS ENTIRE LANDSCAPE WAS FORMED BY THE MISSISSIPPI PICKING UP SOIL FROM ACROSS THE COUNTRY AND DEPOSITING IT HERE.

BUT NOW IT'S AT RISK OF DISAPPEARING BENEATH THE WAVES.

TO TELL THE STORY OF THESE WETLANDS, LOCAL PHOTOGRAPHER AND CONSERVATIONIST BEN DEPP HAS TAKEN TO THE SKY.

THE LANDSCAPE IS TOTALLY FLAT, AND THE ONLY WAY TO GET PERSPECTIVE IS TO GO UP IN THE AIR.

[ENGINE STARTS] ♪ THIS WHOLE LANDSCAPE, HUNDREDS OF MILES OF WETLANDS, WERE CREATED FROM THE MISSISSIPPI RIVER.

THIS LAND IS DIRT FROM A SOY BEAN FIELD IN IOWA AND A CORNFIELD IN OHIO, A MOUNTAINSIDE IN MONTANA, AND IT'S AN INCREDIBLE THOUGHT THAT THAT SEDIMENT IS BEING CARRIED ALL THE WAY DOWN THE MISSISSIPPI RIVER AND IS WASHING INTO WETLANDS HERE AND BUILDING NEW LAND.

NARRATOR: THESE COASTAL WETLANDS MAY BE HUGE, BUT WHAT PEOPLE HAVE DONE TO THE MISSISSIPPI HAS HAD EFFECTS THAT FEW COULD HAVE FORESEEN.

THE LANDSCAPE HERE IS NATURALLY IN A STATE OF CHANGE.

THE RIVER SPREADS AND SLOWS, DEPOSITING SEDIMENT WHICH BUILDS NEW LAND.

THE OCEAN CURRENTS THEN TRY TO WASH IT AWAY.

HISTORICALLY, THE MISSISSIPPI HAS ALWAYS WON THIS CONTEST.

OVER TIME, NEW LAND EXTENDED OUT INTO THE GULF OF MEXICO, GRADUALLY FORMING ONE OF THE LARGEST DELTAS IN THE WORLD.

BUT THE BALANCE BETWEEN SEDIMENTATION AND EROSION HAS BEEN CHANGED.

THE FLOOD DEFENSES THAT LINE THE MISSISSIPPI HAVE BROKEN THE NATURAL CYCLE, MEANING THAT THE RIVER CAN NO LONGER SPREAD OUT TO REBUILD THE WETLANDS.

IN RECENT DECADES, LAND HAS BEEN LOST AT THE EQUIVALENT RATE OF A FOOTBALL FIELD EVERY HOUR.

♪ DEPP: EVERYWHERE YOU LOOK, YOU CAN SEE WHAT WE'VE DONE TO THIS LANDSCAPE.

I THINK WE DIDN'T UNDERSTAND WHAT WE WERE DOING, AND NOW WE UNDERSTAND THAT WE'VE REALLY MESSED UP THOSE NATURAL SYSTEMS.

OVER THE LAST 80 YEARS, WE'VE LOST 2,000 SQUARE MILES OF LAND.

NARRATOR: COASTAL WETLANDS HELP TO PROTECT CITIES LIKE NEW ORLEANS FROM RAGING STORM SURGES CAUSED BY HURRICANES.

AS THE WETLANDS DISAPPEAR, HURRICANE DAMAGE BECOMES MUCH WORSE INLAND.

DEPP: WE NEED TO CHANGE OUR PERSPECTIVE, AND WE NEED TO PRIORITIZE THESE THINGS THAT ARE GOING TO HELP US TO CONTINUE LIVING HERE LONG TERM.

NARRATOR: WORK IS TAKING PLACE TO REVERSE THIS MASSIVE LAND LOSS.

SEDIMENT IS BEING PUMPED AND DIVERTED TO REPLENISH THE MARSHES, AND SAND IS BEING DREDGED FROM THE OCEAN TO REBUILD PROTECTIVE BARRIER ISLANDS.

ALREADY OVER 36,000 ACRES OF LAND HAVE BEEN RESTORED OR PROTECTED, AND MUCH MORE IS PLANNED.

IT'S A CONSTANT AND EXPENSIVE BATTLE AGAINST TIDE AND WIND.

DOWN HERE, AT THE END OF THE RIVER'S JOURNEY, PEOPLE ARE NOW TRYING TO DO WHAT THIS RIVER ONCE DID ENTIRELY BY ITSELF.

DESPITE ALL THE CHANGES THAT IT HAS ENDURED, THE MIGHTY MISSISSIPPI REMAINS THE LIFEBLOOD OF THIS NATION.

♪ THROUGHOUT THE MISSISSIPPI'S ENORMOUS REACH, THE RIVER BRINGS EVERYTHING AND EVERYONE TOGETHER... [BIRDS SQUAWKING] GIVING ANIMALS A LIFELINE AND CONNECTING ITS MANY PEOPLE.

A RIVER THAT UNITES AND DEFINES THE MANY DIFFERENT FACES OF ONE GREAT NATION.

♪ ANNOUNCER: TO ORDER "RIVERS OF LIFE" ON DVD, VISIT shopPBS, OR CALL 1-800-PLAY-PBS.

THIS PROGRAM IS ALSO AVAILABLE ON AMAZON PRIME VIDEO.

♪