Trinity Lakes Still Full, and Fall Rains Are Coming. Uh-Oh.
Water at Grapevine Lake is still covering parts of homeowners' lawns.
We got a spot of rain last week, but for weeks beforehand the weather person on the evening news had been warning me in increasingly dire tones about the drought. The region had gone 40 days and 40 nights without rain, she said, returning us to drought conditions.
So what the hell? I'm a water wonk. I'm constantly checking the web page, "Status of U.S. Army Corps of Engineers and Other Lakes in the Fort Worth District," to see how full the reservoirs are up above Dallas. Think of them as gigantic rain barrels right over our heads. If they gush, we flush.
There are eight reservoirs in the Upper Trinity River Basin flood risk management system, but three of them, Ray Roberts, Lewisville and Grapevine, flow directly into the flood control levee system in downtown Dallas. After almost a month and a half without rain, those three still show up now on the web page as flooded above their maximum capacity. Still.
One, Grapevine, is still 10 feet above the level normally considered to be full. That's way high.
Who cares? Well, count on me to blow up my bridges before I cross them, but I'm already thinking about the fall rainy season. During last spring's unusually long and wet rainy season, flood levels rose high on the levees that protect downtown. But downtown was protected, we were told, because all of that rainwater in the watershed upstream from us was being held back by the reservoirs. When the spring rains started, you will recall, the reservoirs were all at historically low levels. That's why they could hold so much water.
So what happens when the fall rains come, as we know they will, if the reservoirs are more than full already? At that level they would be able to hold back no additional water. And why, after 40 days of drought, have the lakes not been drained back to lower levels? Why are they still flooded?
I don't think my question is as wonkish as it sounds, even to me. The global wisdom on modern flood control, led by the Dutch, is an approach called "living with water." The Dutch doctrine, based on science and a lot of obvious experience on their part, is that man cannot defeat Mother Nature with dams, dikes, levees and reservoirs.
The only way for the Earth to manage most of Mother Nature's rainfall is to allow most of the rain to soak into the ground. The more ground we seal off with buildings and concrete, the more water we try to steer behind walls or try to hold in tanks, the worse we make things and the more catastrophic the inevitable flood when it comes.
The Dutch system is a compromise. It tells Mother Nature, "We have to protect this big city over here no matter what, but you can have all that area over there for the water to soak into the ground."
It's not new. In 1988 the U.S. Army Corps of Engineers, which is the country's de facto national flood control agency, entered into a kind of out-of-court settlement with most of the municipalities along the upper Trinity River. The municipalities agreed not to allow development that would make rainwater runoff worse.
In practical terms, that meant that if anybody wanted to build anything that would cause more runoff, they had to offset it somewhere else in the watershed with land that would absorb or hold more water. Think of it as an effort to make sure there would be no increase in the amount of water going into the river.
That effort appears to have been an overwhelming failure. A study a year ago found that real estate development in the region didn't take place where planners back in 1988 thought it would. Overall growth in the watershed reached levels by 2005 that the planners back then thought would not occur until 2040.
Meanwhile, back during the spring rains when I asked the Corps if they had measured the amount of increased impermeable surface in the region since 1988 — a matter of aerial photography — their full response was, "No."
Why the hell not? That's the whole ticket, isn't it? If we have way more paved and roof-topped territory and not enough offsetting spongy area to soak it up, then we have a much greater flood risk. Right?
Wrong, the Corps and city officials told me. Because we have the reservoirs to hold back the flood water.
Last week when we finally got some rain, I decided I needed to motor on out to Grapevine Lake and eyeball it for myself. Maybe I was looking at some weird statistical deal on that web page, and the lake wasn't really flooded at all, as in ... you know ... water where it's not supposed to be. So I drove to subdivisions in the area northwest of DFW airport, between East Dove Road and the southeast shore of Grapevine Lake.
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If I were Noah and I lived on the shore of Grapevine Lake? I'd be laying in a supply of gopher wood about now. I didn't see houses inundated along the lake, but I definitely saw water still way up on their yards, and I saw parks still far out from shore underneath lake water, with only the rooftops of picnic kiosks showing in the distance.
I talked to Clayton Church at the Corps — well, exchanged emails — and asked him why, after so many weeks without rain, Grapevine Lake is still so far above its maximum capacity. He explained to me that all three of the big lakes right above Dallas in the pipeline have to be drained very, very carefully, at the relative rate of a dribble. It's all about a point on the Elm Fork of the Trinity River that the Corps calls "CART2" — something you and I might call a "chokepoint," but I don't believe the Corps uses that term.
Grapevine Lake flows into Denton Creek flows into the Elm Fork of the Trinity River flows into the main branch of the Trinity and through the levee system downtown. Lake Ray Roberts flows into Lewisville Lake flows into the Elm Fork above where Denton Creek comes in. So all three lakes empty into the Elm Fork above the place I'm calling the chokepoint.
CART2, the chokepoint, is the name of a Corps of Engineers flood gauge installed in the Elm Fork near the intersection of the Stemmons/35E Freeway and the President George Bush Turnpike in Carrollton, about six miles northeast of the airport. Church told me the Corps can't allow the water flow at CART2 to get above 7,000 cubic feet per second or the river will flood in the California Crossing area.
California Crossing? I know that name. It's a historic site. I think it's where the founder of Dallas forded the Elm Fork while naked to make his escape to California after fleecing a community of Mennonites in a pyramid scheme, but I could be mixing up several Dallas history chapters there. Anyway, I looked it up on Google Maps.
Oh, yeah, it's where Northwest Highway cuts over West from the Stemmons to Highway 114 and goes to ... aha! Las Colinas! That's what we're talking about. Las Colinas is where the more recent pillars of the community dug out all those phony lakes and canals so they could build a development that would look like the Venice of insurance company headquarters.
"Currently," Church said, "flows are just above 6,000 and rising."
So that would be pretty close to choking.
In other words, the water has not been drained out of the upstream lakes and they are still flooded, especially Grapevine, because the Corps has been letting the water out as fast as it can without doing serious damage to other areas downstream from the lakes. Which is slow.
Call me Cassandra. Please. I can take it. But, look: A week ago the Dallas City Council voted to divert $47.7 million from a proposal to build an expressway inside the levees system downtown to a loosely defined mission instead of "flood control and parks."
Here is my Cassandra-like plea: At least some of that money should be spent hiring state-of-the-art consultants from as far away as possible, ideally from the Netherlands, to come tell us what kind of overall flood control system we have now and how it's working.
When I look at all of that new residential development clustered around the upstream lakes, I wonder if the people in those houses even know what those lakes are — that they are part of a man-made so-called "flood risk management system" and that the system flies in the face of modern global state-of-the-art flood control knowledge.
Our system is not "living with water." Our system is "fight the water." And in places like New Orleans and the Netherlands, people have learned the hard way that that's a fight we will always lose, eventually and badly.
I worry that no one here in a position of influence or power has an interest in telling us the truth. The Corps certainly doesn't want to tell us it has been complicit for almost 30 years in building out exactly the kind of landscape it swore to prevent in 1988. The real estate development interests, especially in the burgeoning suburbs, will never want to talk about taking land out of development to accommodate flooding.
And as we know, the only thing our leadership here in Dallas wants to talk about is building that expressway between the levees so they can get people in and out of the casino they want to build downtown. I hope they call it Las Colitis.
Church told me the Corps hopes to have the lakes down to the "conservation pool" level by September 15. Conservation pool is the equivalent of full but not flooded.
Think about it. If those lakes had been full at the beginning of the rains last spring, we'd all be wearing water wings by now. Right now they are still flooded, and fall is not that far away.
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