SJRA officials said they released more than double the volume of the 1994 floods—the previous high—to return lake levels to 201 feet, which is the level at which the SJRA must begin releasing water. SJRA General Manager Jace Houston discussed the event, classified as a 500-year storm, and potential solutions.
Why wasn’t water released from the Lake Conroe dam before Hurricane Harvey arrived?
No. 1: We would most likely make their problem worse. If I send water down the river, I’m pre-filling the riverbed. Now, as soon as the rain falls and it hits the creeks and the bayous and the streams and it hits the river, the river has no more room to accept the flow. So the flooding will be faster and the emergency management people will have less time to evacuate people because it will happen more quickly.
No. 2: Because Lake Conroe is so large, I can’t lower [lake levels] more than maybe an inch or two a day without pre-filling the river. The amount I can do without filling the river is maybe an inch a day. Even if I had a five day forecast that was absolutely totally correct, maybe I can move the lake five inches in five days. But five inches isn’t going to help when you’ve got 15 feet of water to deal with. So the thought that pre-release would have any benefit to people downstream is false.
Harris County Judge Ed Emmett discussed turning the Lake Conroe reservoir into a flood control facility in addition to a water supply and recreational area. Do you think it's a good idea?
Because of the severity of all of this flooding, I agree every option should be looked at. I have no problem with considering making part of Lake Houston and part of Lake Conroe into flood control facilities. We ought to study all of the options. However, there are really significant consequences to taking any of the state’s water supply reservoirs and converting them into flood storage.
If you lower the level, a portion of that goes away and you have to replace it with water from somewhere else because the state of Texas is already short on water supply. We already don’t have enough water to meet the future demands of the state, including the Greater Houston region. That would mean we would have to immediately turn around and start making plans for how we’re going to replace that lost water supply. That’s potentially hundreds of millions of dollars.
There has to be a study. There’s going to need to be a tremendous stakeholder input on the pros and cons of converting Lake Houston or Lake Conroe into flood storage. You’re going to have to look at what the economic consequences of doing that are, in terms of replacing water supply and in terms of the impact to the area around Lake Conroe. It would have a negative impact on property values around Lake Conroe, a negative impact on sales tax and property tax revenue.
Is there any way to know if projects at Lake Houston would be more beneficial to preventing flooding?
One of the rules of thumb in the water supply business is you basically start your planning at the top of the basin because you want to start your water supply as high up the hill as you possibly can. But in the flood business, you start your planning at the bottom of the hill.
What if I did a bunch of improvements in Spring Creek or Lake Creek so that water would flow faster down the river, but I haven’t done anything to Lake Houston. I made their problem worse because I made water get there faster.
You’ve got to think about Lake Houston. Is there a way that I can get water out of Lake Houston faster and if there is, would it help? That needs to be looked at. Can we get the water out of Lake Houston faster so that it doesn’t back up when the water is coming down? Because remember there are no dams. Lake Conroe is the only dam in the entire San Jacinto River Basin.
All these other tributaries that contribute 85-90 percent of the flow that reaches Lake Houston, they’re uncontrolled. It’s coming whether you want it or not. So you either have to build flood control reservoirs on those other creeks or you have to go to Lake Houston and figure out how to get [water] out of the lake faster.
Leaders in the Lake Houston area are proposing that the SJRA lower the standing water level at Lake Conroe from 201 feet to 198 feet.
We don’t set that. The state of Texas sets that. It’s set at 201.
During speeches Houston city councilman Dave Martin said the level was raised to 201 from 198 feet after the drought in 2011.
No. The level has always been 201 since Lake Conroe was constructed.
What would it mean for the people who live around Lake Conroe if the water level was dropped three feet?
The way reservoirs are designed is the state of Texas allows you to take a certain amount out each year. [It's based on] if you go through a seven-year long drought, at the end of the seven years your reservoir would be empty. If you lowered the level—instead of starting at 201 you’re starting at some lower amount, then they’ll have to lower that amount that you can take each year and still make it through a seven-year drought.
Right now it’s a 100,000 acre-feet per year. But they would lower the amount of water we’re allowed to use each year. We’re not using the full amount yet anyway. We don’t have enough population to need the full amount. It wouldn’t be a water supply problem tomorrow or the next year. It’s more of a long term issue. It means we would have to go and develop a long-term supply for our future water supply for the region. Not just for Montgomery County. That lake serves the entire region.
The other problem is you’re talking about the you’re talking about the water level being three feet lower than its normal level. For Lake Conroe it’s a pretty shallow lake. When the Lake gets 2 or 2.5 feet below normal you get coves and areas around the Lake where the bottom of the reservoir is starting to show, and it’s too shallow for boats. It impacts people’s ability to use the lake for recreational purposes.
If there were three more feet of capacity would the SJRA have been able to hold water longer in Lake Conroe and released it slower?
That’s the bigger question to me. The thing you have to talk about is would it even help to lower the lake 3 feet. If we know there are consequences to lowering the lake 3 feet then we can estimate a dollar amount for that.
But if it’s not going to reduce flooding then why would you do it?
If it would have eliminated all flooding then it might be worth a few hundred million dollars. Here’s the problem. In Harvey we passed through the gates over 15 feet of lake level—that’s how much water came through Lake Conroe. So if we had started that event three feet lower it really doesn’t change—it would delay the release of water a little bit. I don’t know by how much, but you’ve still got 12 feet of water that you’ve got to deal with and pass through the dam. You’re still going to have a large release of water.
In a really large event like Harvey it doesn’t make a big difference. We could capture a lot of water. So if it’s a 100-year storm event or like the tax day floods from last year… maybe in a smaller event like that it would have an impact on reducing how much we have to release, but in a Harvey event it doesn’t make that big of a difference.
And here’s the other thing. If it’s a Kingwood resident, we are only 10-15 percent of the water that gets to Lake Houston anyway. Even if Lake Conroe had been empty and had not released a drop of water in Hurricane Harvey, they would still have 85-90 percent of the water that they got.
Lake Conroe didn’t cause their flooding. We are a small percentage of their flooding.
What would be the impact of dredging the San Jacinto River and Lake Houston?
I really don’t know what the impact of dredging might be because the siltation over the last several decades has definitely changed the shape and the way water flows through the upper part of the lake and the lower part of the river.