A new island has risen up near the boardwalk on the south shore of Lady Bird Lake. I noticed it on a recent jog, and I’m not the only one.

KUT's Mose Buchele reports

“It’s really weird,” says Patti Lerma, who works nearby. “It just got huge out of nowhere.”

The island is nearly 6,000 square feet and is covered in plants and little trees; its terrain is sandy and firm underfoot.

“Am I the first person ever to set foot on this island?” I wondered as I walked its shores after a recent kayak expedition from the north shore.

The answer is no.

Liz Johnston, with the City of Austin’s Watershed Protection Department, says she’s visited it before. She thinks the land started rising there a few years ago, maybe around the time of the Halloween floods in 2013. That flooding, and subsequent floods, pushed sediment from Bouldin Creek, on the other side of the boardwalk, into Lady Bird Lake. The buildup happened quickly because it’s an urban creek with a lot of water runoff.

“So, historic flood, with urbanization, and we get an island forming,” she says.

These islands are popping up in other parts of the lake. There’s one near Blunn Creek, and Johnston says Shoal Creek has one, as well – dubbed “Bellinger Cay” by Watershed employee Brent Bellinger. They even planted some cypress trees on it.

The city sees some benefit in the new islands. They provide good habitat for plants and animals – the Watershed Department even planted some cypress trees on Shoal Creek’s new island. The islands have grown so much, Johnston says, the city would need to get permission if it wanted to dredge the lake, as not to disturb the islands.

With trees, they may have a better chance of lasting, but over the past few years, their presence has ebbed and flowed with water levels on the lake. A survey of Google Earth images of the island near the boardwalk has appeared and disappeared before – surfacing as early as 2003.

So, why are people noticing it now? Probably because it’s been growing for a while, and it’s covered in plants, but also because it’s the first time it’s surfaced since the boardwalk was built in 2014. So, more people can see it.

So, now that it’s visible, what will Austinites call it?

Lerma suggested “the Recycler,” noting the plastic bottles and other recyclables that have washed up on its shore.

Johnston says the island doesn't officially have a name, though she jokingly suggests “Buchele Cay.”

But my vote’s for Halloween Island in honor of the day, and the flood, that may have helped it rise from the lake.