Dozens of families living off I-35 in San Marcos know the power of flood waters too well.

“They’re heavy. I moved all of these yesterday,” said Cheryl Bailey as she was putting down a sandbag around her mother’s home.

She says she knows how the water can rise fast. It did in 2015.

When the Memorial Day floods hit in 2015 the twin sisters, Cheryl Bailey and Cheri Martin, knew they had to help their mom and dad.

“It was pouring in the front windows,” said Martin.

That year, rain fell fast. The river nearby overflowed. Water back up and into all of the homes on Briarwood Court.

“It was very scary,” said Bailey. “We had to stop and hold my parents in the boat in the waves while they did a helicopter evacuation a couple of houses down.”

“All of the other neighbors were on their roofs. They couldn’t get out at all,” said Martin.

Which is why now it's important to put up the sandbags.

“We all try to take care of each other,” said David Graham, neighbor.

They said they’ll stick together through this storm, too.