Tag Archive for: Hector Olmos

What Happened Downstream During Harvey as Lake Conroe Released 79,000 CFS

Last night, I posted some statistics about Lake Conroe levels after the SJRA started the release during Hurricane Harvey. Tim Garfield and R.D. Kissling, two top geologists, now retired from one of the world’s largest oil companies, have looked at the release from a downstream perspective. Last year, they put everything they learned into this 69-page presentation delivered to the University of Houston Honors Program.

From “A Brief History of Lake Houston and the Hurricane Harvey Flood,” by Tim Garfield and RD Kissling with help from Bob Rehak, 2019.

Recap of Key Points About Lake Conroe Release

To recap several key points:

  • The SJRA never did let Lake Conroe rise to its allowable flowage easement. The water level in Lake Conroe peaked at 7 a.m., August 28, 2017, at 206.23 feet. The SJRA’s flowage easement is 207 feet.
  • Outflow exceeded inflow by 8:30 a.m. on the 28th and stayed that way for the duration of the storm. As the lake level declined, the lake had up to 3 available feet of storage capacity.
  • Yet the SJRA kept releasing, on average, 2X – 10X more water than it was taking in. At one point, the ratio exceeded 100:1.

Tracking the Release Down West Fork

Garfield notes that the discharge ramp up that began the evening of the 27th reached a peak discharge rate of more than 79,000 cubic feet per second (cfs) just before noon on the 28th. The discharge rate didn’t dip below 70,000 cfs until 4 a.m. on the 29th – more than 16 hours later.

Following in lockstep with the Conroe release, flow rates at downstream gauges ramped up, in lockstep. By lining up the peaks of gages downriver, you can literally see the water surging down the West Fork all the way to Lake Houston. (See left side of image above.)

Significantly, Garfield says, these gauges all showed flattening flow-rate curves before the release ramp up. Those curves then turned and steepened upward as the Conroe release pulse arrived at those gauges.

Timing and Impact of Release in Lake Houston Area

Peak flow at the Humble gauge was reached shortly after noon on the 29th, roughly 24 hours after peak discharge was reached at the dam and roughly 30 hours after the high-rate release ramp up began.

Water started creeping under the doors of Kingwood Village Estates, a senior living center in Kingwood Town Center about 1.4 miles from the West Fork, at 3 a.m., on August 29th, 2017. It kept rising all morning and finally stopped another mile further inland. Water entered the last (highest) house to flood in Kings Point (the Kingwood subdivision closest to the main body of Lake Houston) at 2 p.m. that same day, according to Elise Whitney Bishop.

Residents trying to escape as Harvey's floodwaters rose
Kingwood Village Estates residents trying to escape as Harvey’s floodwaters rose. Twelve later died.

The level of upper Lake Houston, as measured at US59, rose an additional 7 feet during this period.

Significant additional flooding of Kingwood homes can be tied to this same period of increased discharge.

Flow rates measured at the Grand Parkway gauge and calculated at the Humble gage indicate a flow rate increase in this period of between 70,000 to 80,000 cfs, corresponding closely to the 79,000+ peak flow rate added by the Conroe dam discharge.

“The data from the affidavits further supports several key conclusions from the Harvey Flood Fundamentals section of our University of Houston talk,” said Garfield. Those include:

  • The large sustained release from Lake Conroe made West Fork flooding worse. The extra 80,000 cfs increased the West Fork flow 50%.
  • The release occurred as the storm was abating. It significantly increased flood damage in the Lake Houston area.
More than 4,400 structures flooded in Humble and Kingwood along the West Fork. Source: HCFCD.

The list of damages ran well over a billion dollars.

The SJRA Argument

The SJRA maintains to this day that Lake Conroe is a water-supply reservoir, not a flood-control reservoir. See the affidavits of Hector Olmos and Chuck Gilman. Olmos is a consultant who helped design the operations manual for the gates at Lake Conroe. Gilman is the SJRA’s Director of Flood Management, hired the year after Harvey.

They are basically claiming, “We don’t have the right tool to prevent downstream flooding.”

Editorial Opinion

Editorial opinion: That excuse has always sounded hollow to me. It attempts to curtail discussion of whether the SJRA waited too long to start releasing water, released too much at the peak, and then kept on releasing too much for days.

That discussion is a matter of public concern that could save lives and property in the future. We need to have it.

Sadly, it will take the courts to figure this out. In the meantime, the SJRA has hired some of the highest priced lawyers in the country and now appears to be angling for legislative immunity by hinting at higher water prices “statewide” if liability can’t be controlled.

It all smacks of similar arguments in other industries. If you’ve lived long enough, you’ve heard them all before, such as car companies that would be driven out of business if forced to install seat belts and other safety features. Well, that prediction didn’t quite work out! Luckily, for General Motors, the addition of safety features helped fuel its resurgence.

Posted by Bob Rehak on 6/12/2020 with thanks to Tim Garfield and RD Kissling

1018 Days after Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Operational Statistics from Lake Conroe Dam During Harvey Raise Troubling Questions

Two affidavits in a lawsuit filed against the SJRA for flooding downstream residents during Harvey contain statistics that raise several troubling questions about the operation of gates during the storm.

  • Did the SJRA wait too long to begin releasing water in significant volumes?
  • As a consequence, did it create an unnecessarily high peak discharge?
  • Did it maintain high discharge rates longer than it needed?
  • As lake levels declined, why did the SJRA continue releasing 2X to 10X more water than it was taking on when it had up to 3 feet of storage capacity in the Lake Conroe?
  • Why did it never let the level of Lake Conroe reach its flowage easement max?
  • Could different procedures have reduced downstream flooding?
Part of one page of seven pages of gate operation statistics in affidavits.

Affidavits of Gilman and Olmos Contain Insights

The first affidavit comes from Chuck Gilman, the SJRA’s Director of Flood Management. It contains a gold mine of statistics. Tables at the end of the affidavit show the date, time, average lake level, total inflow, and total discharge (cubic feet per second), and the exact time of gate changes. The statistics start August 26, 2017 at 10 p.m. They end three days later at the same time. The seven pages of statistics capture a snapshot of the storm and the SJRA’s response hour by hour during Harvey. At the peak, the SJRA recorded changes every 15 minutes.

The second affidavit comes from Hector Olmos, a Principal and Vice President of consulting firm Freese and Nichols, Inc. Olmos helped develop the gate operations policy for at Lake Conroe for the SJRA. The Olmos affidavit contains the same statistical information in Gilman’s. However, it also contains more details of the Gate Operations Policy in place at the time of Harvey. And the two affidavits assert different facts.

Download Gilman Affidavit

Download Olmos Affidavit

Inflow Vs. Outflow and Flowage Easement Max

In the summary that follows, outflow vs. inflow rates are significant. Gilman swore in his affidavit that the gate operation “…policy is programmed so that even in the most extreme situations, peak outflow will never exceed 70% of inflow.” “Peak” is the key word there. Olmos swore in his affidavit that 80% was the limit. However, statistics show that it never significantly exceeded 60%.

As you review the following, keep in mind another key point. SJRA had the ability and authority to increase the lake level to 207, but stopped short at 206.23 for some reason that the affidavits don’t explain.

Summary of Key Statistics and Actions

Key statistics show that:

  • Lake Conroe started to rise at 11:30 p.m. on August 26, 2017 in response to 1,722 cfs flowing into the lake.
  • After the lake level reached 201.04 feet at 12:15 a.m. on August 27, SJRA first opened its gates at 12:25 a.m. and started releasing 529 cfs.
  • After that, inflow generally increased for the next 24.5 hours, though the increases were not a straight line. Inflow fluctuated up and down, likely in response to feeder bands passing over the watershed or variations in readings due to wave and wind action.
  • More than 24 hours after the start of the storm, at 1 a.m. on August 28, inflow peaked at 129,065 cfs. By then, the lake level had reached 205.65 feet and the SJRA was releasing 62,082 cfs, less than half of the inflow.
  • From that point on, the inflow generally declined, but not in a straight line.
  • The water level in Lake Conroe peaked six hours later at 7 a.m., August 28, at 206.23 feet. That’s roughly three-quarters of a foot BELOW the SJRA’s flowage easement.
  • After that, water continued to go down for the duration of the storm, but the SJRA continued increasing its release rate for five more hours, until 12 noon on the 28th. The water level was 206.17 feet, almost a foot below its flowage easement. Inflow was 63,986 cfs (less than half the peak), yet discharge peaked at 79,141. So the lake level and inflow were going down, but the discharge rate kept increasing when the lake had room to spare.
  • SJRA kept the release rate above 70,000 cfs until 4:15 a.m. the morning of the 29th, more than 16 hours. By then, the lake level had gone down to 204.58. And the discharge rate was still three times higher than the inflow (71,538 cfs discharge vs 20,287 inflow).
  • For the rest of the storm, lake level, inflow rates and discharge rates all continued to decline. The table ends at 10 p.m., August 29th. Lake level equaled 203.44, discharge 22,033, and inflow 6,579.

Turning Points in the Storm

During the entire day of August 27th, outflow fluctuated roughly from 16% to 50% of inflow as the inflow kept building relentlessly.

Outflow exceeded inflow by 8:30 a.m. on the 28th and stayed that way for the duration of the storm even though the lake had up to 3 available feet of storage capacity.

By the morning of the 29th, downstream areas were flooding badly. The SJRA had roughly three feet of extra storage capacity in Lake Conroe within its flowage easement. Yet it kept releasing, on average, 2 – 10X more water than it was taking in. At one point the ratio exceeded 100:1.

Could the SJRA have used more of Lake Conroe’s available storage capacity as lake levels declined to help reduce downstream flooding?

Neither Mr. Gilman’s, nor Mr. Olmos’ affidavits shed light on these issues.

Please Note

Chuck Gilman inherited this problem. The SJRA did not hire him until well after Harvey.

Also note that conditions during an emergency can be chaotic. Keyboard quarterbacking after the fact is much easier.

If the SJRA wishes to respond to this post, I will print its position verbatim.

Posted by Bob Rehak on 6/11/2020

1017 Days after Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.