A Closer Look at Sand Issues on the East Fork of the San Jacinto

This is what East End Park used to look like – a natural gem within the nation’s fourth largest city, an urban refuge for wildlife on the East Fork, and an island of quiet enjoyed by more than 80,000 visitors per year.

Then Things Changed

After Harvey, sand and gravel dunes covered 30 acres (about 20 percent of the park’s 150 acres). The sand destroyed wetlands. Look at the wetland image three rows up in the center of the poster. Now look below. They’re the same area!

This bridge had to be excavated from several feet of sand after Harvey. It used to cross wetlands shown in the poster above.

Here’s what the trail looked like in the opposite direction before excavation.

Standing on five feet of sand deposited in East End Park wetlands

 A bird’s nest ten feet up in a tree is now knee high because sand raised the ground elevation so much.

Natural or man-made disaster?

So I asked myself, where did all this sand come from? Was this just something that you have to accept when you live near a river? To find answers, I rented a helicopter and flew up the East Fork. Opposite East End Park, I saw this giant dune below, one of several along the way.

A new dune deposited during Harvey now blocks half of the East Fork opposite East End Park (upper right).

From ground level (below), you can see how tall it is – 10 to 12 feet. Some people who have climbed this dune tell me that it gets even higher back in the trees.

This new sand dune, created during Harvey is twice the height of the average human. A geologist told me that he doesn’t usually see changes this dramatic on a human time scale. 

Farther up the river, I started to see what the problem might be.

A 750 acre sand mine hugs the banks of Caney Creek. Note how another giant sand bar adjacent to the mine again chokes off 50 percent of Caney Creek. Such blockages are now common.

As I flew around the northern part of the mine and started looking south, I saw large areas that are not being actively mined, yet are un-vegetated. This makes sand more susceptible to erosion in floods. 

Flying closer to the giant stockpile, I noted its height relative to trees around it. Those trees typically grow up to 100 feet tall. That water tower in the background is on Kingwood Drive. 

As I got closer to the stockpile, I noted ripples/wave forms in the lower part on the left and the remnants of heavy erosion from rainfall on the right. These are signs that water had been moving through the interior of this mine pretty quickly and that the dikes around them were no barrier to erosion.

Below, note how the road that comes up from the bottom left washed out inside of the mine.

 Satellite imagery in Google Earth shows that the washout most likely happened during Harvey. It first shows up in satellite photos on 9/1/17.

I reviewed other areas within this mine in Google Earth. The mine measures more than 750 acres. The stockpile alone comprises 34 acres. The image below from 9/1/17 reveals severe erosion of this massive stockpile as Harvey’s floodwater’s receded.

Erosion in East Fork sand mine stockpile as Harvey’s floodwater’s receded.

Evidence Mounts: Clearer Picture Emerges

Satellite imagery below shows that no other sand mines are visible on the East Fork or its tributaries for miles around. None of the rivers or streams in this area seem to produce much. And all of those monster sand bars appear downstream. Hmmmm! Had we found the source of all that sand?

No other sand mines exist on Caney Creek. No huge sand bars show up above the mine; all appear below. Note that the sand bars represent only a tiny portion of the sand carried downstream; as in East End Park, huge volumes were deposited beneath the forest canopy and are not visible in satellite imagery.

Mine Located in Two Floodways; Living Dangerously

At this point, I had my suspicions. But TACA claims that “when rivers back up into a mine during floods” they slow down and drop their sediment in the pits. I puzzled over the phrase “back up,” especially because this mine, like virtually all others in the area, sits in a floodway. Actually, this one sits in TWO.

Half of this mine lies in two floodways as shown in this USGS flood hazard viewer. The part of the stockpile that eroded most is in the the 100 year floodplain (aqua). See right side of circle. Brown represents the 500 year flood plain and the cross-hatched area represents the floodway, which is defined as the main current of the river during a 100-year flood.

According to Harris County Flood Control on page 12 of their final report, more than 20,000 cubic feet of water per second came down Caney Creek. And the Flood Control District has no gauges on White Oak Creek, the tributary that comes from the west, so the real flow total was higher. I can’t imagine how water would “back up” into this particular mine during an event like Harvey, especially during the early stages when everything was rushing downstream fast enough to wash out a road and erode a mountain of sand.

But still, those TACA guys are the experts, right?

I needed a way of showing exactly how fast the water was flowing through this area. Since there are no gages, I looked at particle sizes deposited downstream. Science tells us that rivers pick up particles in a particular order as flow increases and accelerates.

Erosion and Deposition of Various Particle Sizes at Different Velocities.

Among the new sand dunes at East End Park, I found gravel…lots of it.

Dunes of gravel or small pebbles were also found in East End Park.

If the current during Harvey was strong enough to pick up 2.5 centimeter pebbles like the one below, it was definitely strong enough to pick up sand. You can even see sand mixed in with the pebbles if you look closely.

Pebble found at top of ten-foot mound in East End Park. It measures about 2.5 centimeters.

To deposit gravel this size, the river was moving at about 150 cm/second – fast enough to pick up EVERYTHING smaller, including clay, silt, sand, gravel and pebbles (items listed below the horizontal axis on the chart above). The flow rate was high enough to move every type of material found in the mine.

While the sand miners claim the river wasn’t moving fast enough to carry sand out of the mines, the physical evidence suggests a different story.

Sand deposits reach high up on trees and are killing many smaller trees. The sand came from somewhere. There’s one likely culprit in my opinion.

Homes Flooded on East Fork, Too

This entire sequence shows the risk of locating mines in floodways. Not just because of damage to nature, but because of danger to homes. Harris County Flood Control compiled this damage map.

1290 structures in Huffman and Kingwood flooded on the sand-clogged East Fork. See the purple and green totals right of the black line that bisects the purple. Those represent damaged structures in the East Fork watershed.

Harvey damaged 1290 Harris County structures in the East Fork watershed. Assuming an average loss of $250,000 for each structure and its contents, damage would total about $350,000,000 – one third of a billion dollars.

Recommended Next Steps

Even though no sedimentation surveys have yet been completed on the East Fork that could definitively link this sand to subsequent flooding, the Army Corps of Engineers has confirmed that similar sand blockages have contributed to flooding on the West Fork. (The Corps is currently embarking on a $70 million dredging project there…at taxpayer expense.)

My findings suggest that such a study should be done on the East Fork. Further, I believe that we need to:

  • Debate whether to allow sand mining in floodways, especially so close to the source of drinking water for 2 million people; sediment is rapidly filling the lake at an accelerating rate.
  • Strengthen permitting requirements, setbacks and best management practices
  • Enforce them by imposing prohibitive fines for violations.

Need to Strengthen TCEQ

Regarding the last point, in the five years from 2013 to 2017, the TCEQ found 619 violations at sand mining operations throughout Texas, but assessed only $506,151 in penalties. That’s about $101,000 per year and works out to an average of $817.69 per fine.

I know Texas is a business-friendly state; that’s why I moved here 40 years ago. But really! This is like the Legislature giving the Domino’s guy a license to speed 90mph through school zones so he can make more tips.

Those are my opinions on matters of public policy protected under the first amendment of the U.S. Constitution and the Anti-SLAPP statutes of the great State of Texas. I sincerely hope that TACA can come to the table and help structure sensible mining regulations that protect the public, not just the profits of miners. I’ll talk more about what those might be in subsequent posts.

Urgency also Needed

It’s important that we start this dialog now. If the new USGS data is correct, Harvey was not a 1000-year event; USGS estimated that the flow on Caney Creek, upstream from the mine, had an annual exceedance probability of 3.3.  See Page 9, Table 3, Line 32 for Gage #08070500 in their report titled “Characterization of Peak Streamflows and Flood Inundation of Selected Areas in Southeastern Texas and Southwestern Louisiana from the August and September 2017 Flood Resulting from Hurricane Harvey.” The report was produced in cooperation with FEMA.

That would make Harvey a 33-year event in this area. Impossible, you say! The flow measured upstream from the mine was only the fourth highest on record.

Posted by Bob Rehak on 7/25/18

331 Days since Hurricane Harvey