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Louisiana is losing its coast faster than any place in the world. That's because of sea level rise, development and sinking marshland. Officials are trying to rebuild those marshes and the wetlands, but much of the coast can't be saved. As Tegan Wendland at member station WWNO reports, Louisiana's history is an unwitting victim. As land disappears and the water creeps inland, ancient archaeology sites are washing away.

TEGAN WENDLAND, BYLINE: Richie Blink was born and raised in Plaquemines Parish, way down south of New Orleans along the Mississippi River. Now he works for the National Wildlife Federation. When he was a kid, his dad showed him a special place in Bay Adams where they'd go fishing.

RICHIE BLINK: We would come out of the floodgates and my dad would say, head for the lemon trees.

WENDLAND: What's locally known as the lemon trees is a stand of weathered old trees on a grassy tuft of land. It's a well-known landmark for fishermen, but they would rarely stop there to hunt or fish because it's a sacred Native American site.

BLINK: The legend goes that you should always bring some sort of sacrifice, so somebody left some lemons for the ancestors.

WENDLAND: And those grew into big trees with grapefruit-sized lemons. But as the land was lost to the Gulf of Mexico, saltwater made its way into the freshwater marsh, killing off the trees and other plants. They stand like skeletons on the edge of this scrappy, wind-beaten island. Waves beat against the dirt, washing it away, exposing shards of ancient pottery. Blink hops down off his boat, pulls it up on the eroding bank and reaches out to pick up an unassuming brown shard out of the waves.

BLINK: You can see it's just everywhere, all over the place.

WENDLAND: What do you have there?

BLINK: This is earthen pottery made by natives, and this site is in the process of being destroyed. It only has a few more years left.

WENDLAND: It's an ancient Native American site and an important archaeological find, and it's one of many historic sites being forever lost to the Gulf as rising seas and saltwater intrusion eat away at Louisiana's fragile marshes. It's not just this one, two sites like this are lost each year. When Blink saw how fast it was eroding, he decided to find an archaeologist and ask for help. That led him to Brian Ostahowski. He gets a lot of calls like this at least once a month, people who say...

BRIAN OSTAHOWSKI: I have a great archaeological site in my backyard. Chances are they probably do.

WENDLAND: So we hopped in a boat with Richie Blink and went out there.

OSTAHOWSKI: Richie wasn't lying. This is actually a very, very important archaeological site.

WENDLAND: Based on the pottery and soil, Ostahowski he says native people lived at the site 3 to 500 years ago. The pieces of broken pottery are probably from an ancient trash pile called a midden. There could even be human remains there.

OSTAHOWSKI: You're talking about a whole ceremonial center that could tell you about life ways or the change of life ways that's going to be completely gone within 10 years. It maybe took 300 years of occupation there.

WENDLAND: Three hundred years to build it, in just 10 years it could be erased. Ostahowski took samples of the soil for radiocarbon dating. Unlike the usual slow-paced archaeology dig, Ostahowski wants to excavate the mound as soon as possible and study the pottery shards and oyster shells, but the truth is there just isn't much time.

OSTAHOWSKI: We're talking about different ways that we can come up with kind of emergency action, emergency excavations.

WENDLAND: He wants to learn more, like how long people lived there and how many different occupations there might have been. These details could help fill gaps in our understanding of the prehistoric Plaquemine culture, which includes tribes that lived on the lower Mississippi before Europeans came. For Blink, it's more than ancient history at stake, it's personal history, where he grew up. He honors that in his own way.

Did you ever bring offerings when you came out?

BLINK: Yes.

WENDLAND: Like what?

BLINK: Two weeks ago I brought some lemons.

WENDLAND: And under a windswept tree on top of the small mound, a handful of dried up lemons sits in the shade. For NPR News, I'm Tegan Wendland in Plaquemines Parish, La.