The Mouth Bar: A Dam Behind the Dam

As tonight’s town hall meeting with Houston Mayor Sylvester Turner, Council Member Dave Martin, Chief Resiliency Officer Steve Costello and Chief Recovery Officer Marvin Odum approaches, it’s important to understand that the U.S. Army Corps of Engineers is NOT currently scheduled to dredge the mouth bar at the confluence of the West Fork and Lake Houston.

The scope of the current West Fork Emergency Dredging Project includes 2.1 miles between River Grove Park and Chimichurri’s. The Corp will remove 1.8 million cubic yards of sand clogging the river in that area. However, they will leave two to three times that much sediment at the mouth of the West Fork – between King’s Point and Atascocita Point…unless something changes soon.

The “Mouth Bar,” a giant sand bar that blocks the West Fork of the San Jacinto, backing the river up into Kingwood and Humble. Water depth is generally 1-3 feet around this bar. Max channel depth in places is just 5-8 feet.

The “mouth bar” which we have talked about extensively in previous posts forms a dam of sorts behind the Lake Houston dam. It backs water up into the heavily populated Humble/Kingwood/Atascocita corridor.

Tim Garfield and RD Kissling, two local retired geologists, first sounded the alarm about this blockage. Since then, many people have been working to bring the mouth bar within the scope of the current project. Garfield and Kissling have also continued to review Corps survey data and developed additional insights.

Tonight Garfield and Kissling shared these thoughts.

  1. You could walk along the red line from Scenic Shores to Kings River Estates, and except for crossing the paleo channel at five to eight feet, you would not even get your shirt wet. It should be approximately 25 feet deep in this area.

    Shallowest path follows red line.

    The Corps survey data is in the background. The red line represents the shallowest points of the lake/river.

  2. Without removing the mouth bar, water will have to flow uphill approximately 40 feet between the West Lake Houston Parkway Bridge and Lake Houston.

    Water will have to rise approximately 40 feet between West Lake Houston Parkway and the Mouth Bar to reach Lake Houston. Subtract five or six feet for the deepest parts of the channel on either side of the bar.

  3. If the city dropped the lake level 12 feet overnight – but the mouth bar remained – you would see an earthen dam 6 feet higher than the lake, behind which West Fork floodwater would still back up and flood our neighborhoods.
  4. Adding flood gates without removing the mouth bar will not protect us from flooding.

With those happy thoughts, let’s hope that the City has some good news to share tonight re: removal of the mouth bar. Council Member Martin and others have been working diligently with the County, State, and Federal Governments to include the mouth bar in the current dredging project or fund it as a second project that follows the first closely.

Doing so could save taxpayers $17 million in mobilization costs.

The meeting will be held Tuesday, October 9 at 6:30 p.m., at the Kingwood Community Center, 4102 Rustic Woods, Kingwood, TX 77345.

Posted by Bob Rehak on October 9, 2018

406 Days since Hurricane Harvey