Not Doom-Saying, Not Cassandratizing, but Keep an Eye on Those Lakes, OK?
First of all, I hope you will at least extend me the courtesy of accepting that I do not want to see the city of Dallas swept away to Galveston on the foaming teeth of a tsunami, especially if it involves me being up there on the teeth in any way.
All I am saying is: watch.
Here come the fall rains. Colleen Coyle, the Channel 8/WFAA weather person who is my own personal guru on matters meteorological, says we’re in for a soaking.
A year ago at the beginning of the fall rains, regional flood control reservoirs were at two-thirds capacity, according to the Texas Water Development Board. That’s about where they were four months later toward the end of February when an early and very wet spring rainy season began.
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Three months after that, by the end of May, reservoirs were over-topped, full to the brim and flooding surrounding areas, especially the three lakes most directly connected to the Trinity River through downtown Dallas — Ray Roberts, Lewisville and Grapevine.
But Colleen and the rest of the weatherologists have been telling us all summer long how drought has returned to North Texas, with weeks and weeks between minuscule rain amounts. In late August when we last talked about this, Clayton Church, spokesman for the Fort Worth District of the U.S. Army Corps of Engineers, was telling me the Corps, which runs the reservoirs, would have them all back down to “conservation pool” levels by September 15.
1908 flood of the Trinity River at Dallas
Library of Congress
Yeah. That’s right. They do. But guess what. “Conservation pool levels” means full. The difference between last spring when the rains started and now is that today, as the fall rains begin, all of the reservoirs in the area are at a combined water volume of 91.5 percent of their full capacity.
And look more closely: Those three that are right upstream from us, Roberts, Lewisville and Grapevine, are still full almost right up to the brim. Roberts is a half an inch below full. Lewisville is 0.9 of an inch below capacity. Grapevine is 0.8 of an inch below.
What does any of that mean? You know, I’m a liberal arts major here. It’s hard for me to assign much reality to huge volumes of anything, especially water because it’s clear. And I have no idea what being clear would have to do with anything. See what I mean?
But I did do a little figuring. The reservoirs last spring were at a low level. Then they filled up. The difference between the low level last spring and the full level is 407 billion gallons. How much is 407 billion gallons? I think it’s like really, really a lot.
Who cares? Well, here’s the thing. We tend to think of the reservoirs as drinking water. I actually think of them as kayaking water. But that’s not why the Corps builds them. One of the primary functions of the reservoirs is to act as our main system of flood protection. They are holding tanks for runoff water from rainfall — water that can’t soak into the ground because we paved it.
The 407 billion gallons of water that went into the reservoirs last spring is 407 billion gallons that would have been flood water all over the area without the reservoirs.
How I see Las Colinas maybe a month or so from now.
Simon de Myle, c. 1570, "Noah's Ark on Mount Ararat," via Wikipedia.
So now you see what I’m getting at, right? The reservoirs could hold all that water last spring because they were a third empty. Now they’re at 91.5 percent, and the ones right upstream from us are full.
Why didn’t the numbskulls drain them, you ask, while we were having a drought all summer? Oh, you know, they’re not really numbskulls. If there are any numbskulls in this, it’s us, because we have allowed dense development to take place all crowded up next to the creeks and canals that serve as drainage conduits for the reservoirs.
Therefore, the Corps could only drain the reservoirs a trickle at a time to avoid flooding the developed areas downstream, even though we were in a drought. The drought wasn’t long enough to get it done. And now we’re about to be back in the wet again already.
My contention is that the whole system is stupid and can’t really work. It’s a fall-back position the Corps was forced to adopt after it failed to control rainwater run-off. It failed to control run-off because the only way to control run-off is to control suburban sprawl, and need I say more? The only way anybody was ever going to control sprawl in this area was with something like drone strikes.
Didn’t happen. We have sprawled from horizon to horizon, and billions of gallons of rainwater have no ground into which to soak, so that water winds up in the reservoirs.
Those reservoirs are already full. A full bucket can’t hold more water. Here come the rains. Watch. Knock on wood. At least toss me a sandwich as I float by.