San Jacinto West Fork Reroutes Itself Through Giant Hallett Mine

The San Jacinto West Fork has rerouted itself through the giant Hallett sand mine in Porter. The old river bed has been cut off. And the river now enters and exits one of the mine’s largest pits through large breaches in what used to be dikes.

More than Normal Erosion

Rivers always move during floods through erosion. But this represents a far larger than normal amount of movement through a process called pit capture.

The river now runs through the Hallett pit instead of following its normal curving channel.

See photos below.

The loss of the dikes is likely the result of the SJRA releasing 71,000 cubic feet per second from Lake Conroe during the peak of the recent flood. That was the second largest release in the history of the SJRA.

Pictures taken just before the peak of the flood show the river already overtopping the pit’s dike. Dikes are like walls that separate the river from the mine’s pits. They keep industrial wastewater out of your drinking water.

Weak Sand Mining Regulations Brought This On

Two other contributing factors are the depth of the pit compared to the depth of the river and with width of the dike.

• When pressure builds up as the floodwater rises, the force pushes on the dike. If the pit is deeper than the river, it can push the dike inward toward the pit.
• And if the dike is not wide enough, again, floodwaters can push the dike inward toward the pit.

That seems to be what happened here.

Until recently, Texas was one of the few states (if not the only one) that had no minimum setbacks of mines from rivers. Bill McCabe of the Lake Houston Area Flood Prevention Initiative was instrumental in lobbying for greater setbacks. The TCEQ adopted them in 2021, but this pit predated the new regulation and the TCEQ did not enforce the regulation in this case.

In fact, this pit was open on its southern end since January. That breach was already expanding before the recent flood.

Pictures Taken Before and After Flood Show Pit Capture

Pictures taken during and after the flood show the impact.

Following the river around to the right, you can see how much sand the river laid down. This likely happened when the volume of water moving through the channel decreased as the velocity decreased, allowing suspended sediment to drop out of suspension.

This video shows the height of the sand deposited in the river bed when the river started flowing to the pit instead of following its normal channel.

Impacts Associated with Pit Capture

Without a river to remove sand from the confluence of the ditch and the river, more and more sediment will likely build up here.

Academic literature discusses the impact of “pit capture” on:

• River bed degradation
• Bank erosion
• Channel widening
• Infrastructure damage or destruction
• Loss of riparian vegetation
• Habitat damage
• Degradation of water quality.

In regard to the last point, sand mining also frequently stirs up heavy metals such as lead and cadmium, which have been documented in academic literature. However, I have no evidence that such chemicals are coming from the Hallett Mine.

This river, which now flows through the Hallett pit, flows into Lake Houston. And Lake Houston is the source of drinking water for more than 2 million people.

Posted by Bob Rehak on May 11, 2024

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The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

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