What is that stuff spreading across Lady Bird Lake?

AUSTIN (KXAN) —  What's all that stuff growing on top of Lady Bird Lake?

According to the Austin Watershed Protection Department, these pervasive plants are Cabomba Caroliniana -- also known as fanwort.

The plant lives in Austin's waterways year-round, but it grows when the temperatures get hotter.

"We try to paddleboard and kayak quite a bit, we don't really do it out here as much anymore because we get stuck right here," said David Ward, who pointed to a large patch of the fanwort near Lamar.

The fanwort has grown a lot in the last few weeks, and in some areas, it stretches across Lady Bird Lake -- which makes it a challenge to get through for anyone out on the water.

"It wasn't a problem when I first moved here and I feel like each year it has gotten worse," said Maci Marullo, who was out walking the trail.

The City of Austin's Watershed Protection Department tells us they don't use any treatment or remove the plant. However, the plant is dispersed naturally when there is a large rain event.

The plant should be avoided, as it serves as a natural habitat to a lot of aquatic life. It can also pose a danger, as it can entangle anyone who falls in.

Although the fanwort plant is not poisonous, it can collect toxic blue-green algae -- which can be deadly for dogs.

"It looks like something out of a sci-fi film like literally," said Gerardo Gomez, who was visiting from Boston. "It does not look pleasing. I would not swim in it whatsoever. No first dates here."

The plant can grow to about 15 feet underwater according to experts.

"I would love for it to be gone honestly," Ward said.

Despite many people wanting the plant removed, The city explains it's a sign of the lake's ecological health.

Businesses along the lake can hire a contractor to remove the plant mechanically as long as they get a permit from Texas Parks and Wildlife.