According to a release from the USCG, they were called to the "oil spill in the Houston Ship Channel near the Lyondell terminal" around 12:40am Saturday.
Officials said the ship channel is open, but transiting vessels are urged to keep their speed to a minimum to minimize their wake.
A helicopter and crew from Air Station Houston was on scene Saturday morning, as well as marine response investigators from Sector Houston-Galveston.
Responders contained the spill with boom and clean-up continued Sunday.
The source has not been determined, but it was not a continuous leak. Officials said only a small amount was spilled. An exact amount was not released.
Stay with Eyewitness News and abc13.com for more information as it becomes available.