The Trinity Toll Road won’t flood

Today I saw a Trinity Vote (the “yes” crowd) brochure featuring a flooded Trinity River from 2007. Clearly they haven’t backed off the spirit of ignorant predictions of flooded roadways by former councilmen John Loza and Sandy Greyson.

Here’s the truth.

To inundate the toll road, a flood would have to crest at least 415.64 feet above sea level, and probably a few feet more due to a mini-levee on the toll road’s river side. That is at least per the designs. Click on the picture at right to see a higher resolution version.

The USGS’s Trinity Gage 08057000, (yes, it’s spelled “gage“) located near the Commerce St. bridge, has the river’s bottom at 368.02 feet above sea level. Simple mathematics says the river has to be at least 47.62 high, a whopping 17.62 feet above flood stage, to get on the toll road.

This gage has taken daily readings since 1987. I put the readings in a spreadsheet, ordered them by height, and found that the highest reading in these 20 years was 45.77 feet from May 3, 1990. This even includes readings not formally approved for publishing. Only 15 readings out of 11,814 (some days have more than one reading), or 0.1%, are even above 40 feet.

What does this mean? In the prior 20 years, the river never rose high enough to flood the road.

What’s clear is that if this road even floods, it’s going to be incredibly rare, possibly counted on one hand during a person’s lifetime.

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