TxDOT says heavy rain has flooded the river beyond its banks. Floodwaters are now covering all lanes of the highway.
There is no indication yet how long the highway will be closed.
The Harris County Flood Control District says flooding has reached its second highest levels ever recorded, surpassing floods in December 1991 and October 1994.
We're following this story on Eyewitness News. Watch for updates on air, online and on our mobile news app.
Keep checking back on this page to get real-time updates as this story unfolds. To get alerts for breaking news, download the abc13 news app for iPhone or Android. You can also get breaking news alerts sent to you by email.