To the north of Houston, and forming part of the border between Harris and Montgomery Counties, is Spring Creek. Many miles of paddling access are provided by public parks and right of way, with more under development. For best description and map, go to the Spring Creek Greenway Web site at:
Be forewarned that their map turns conventional north and south directional orientation upside down. Montgomery County is to the north of Harris County; once you get the orientation right, you'll be set to go paddling. You should also know that to use Jesse Jones Park and Nature Center as either putin or takeout requires prior approval from the park.