The Case for Lowering Lake Conroe Two feet During Hurricane Season

By: Bob Rehak
Lake Houston Area Resident

On April 26, in response to pleas from Lake Houston residents and a directive from the governor (to protect downstream residents from flooding), the SJRA board voted to lower the level of Lake Conroe temporarily. The lowering would amount to one foot during the rainiest months in spring and up to two feet during the peak of hurricane season in late August and September.

I say “up to” because Lake Conroe looses on average of more than a foot and a half due to evaporation by September. The most likely reduction would be only an additional 4.8 inches. In no case would the SJRA manually lower the level of the lake beyond 199 mean feet above sea level (msl).

Nevertheless, in an open letter posted on May 11, the president of the Lake Conroe Association says his group MUST FIGHT a 2-foot reduction. He makes three arguments. Two feet would: 1) make shallow docks unusable, 2) harm tourism, and 3) reduce values of Lake Conroe homes. He says, “Families expect to enjoy their investment...’”

In the letter, he does not address how long SJRA intended the two-foot reduction to last. Nor does he discuss whether it is necessary to protect downstream residents, so allow me.

These seasonal reductions would only last until the threat to downstream residents can be reduced through other measures. In practical terms, that likely means until: 1) the U.S. Army Corps of Engineers can dredge sand buildups that exacerbate West Fork flooding, and 2) the discharge rate of Lake Houston can be synchronized with Lake Conroe’s to eliminate a bottleneck in the river system. SJRA would re-evaluate the need for temporary, seasonal reductions each year and stop them when these other mitigation measures reduce flood risk.

Downstream residents understand that lowering the lake level will make it difficult for some Lake Conroe residents and businesses to use their docks. However, a temporary lowering should not result in any permanent losses. Lake Conroe goes down almost this much naturally every year. Yet still it bounces back. The area is still renowned for its beauty and recreation. And home values have climbed steadily.

Real, Not Potential Damages

Meanwhile, the damage from flooding downstream has devastated thousands of homeowners and businesses.

According to the SBA, more than 16,000 homes and 3,300 businesses in the Lake Houston area suffered damage during Harvey. A survey last month at a meeting of the Lake Houston Area Grass Roots Flood Prevention Initiative showed that half of the residents are still not back in their homes – eight months after Harvey! Likewise, many businesses still have not reopened and many never will.

If you think the flood affected only people who built “too near the river,” think again. I live 1.7 miles from the river in a subdivision where 40 percent of the homes flooded. Many of my neighbors still live in hotels, with friends, or in campers as they try to restore their homes. Home damage in our little 350-acre neighborhood totaled an estimated $40 million. Most residents didn’t have flood insurance because they were nowhere near the flood plain. To finance repairs, many have taken on long-term debt, burned through retirement savings, or cashed in their children’s college funds.

Also, because of West Fork flooding during Harvey:

  • Union Pacific had to replace its bridge, disrupting rail traffic for weeks.
  • TxDOT had to replace part of the I-69 Bridge, creating massive traffic delays during rush hours for months.
  • 44 percent of all Lake Houston Area Chamber businesses were adversely affected.
  • 100 percent of Humble businesses between Deerbrook Mall and the West Fork flooded on both sides of I-69.
  • 100 percent of Kingwood’s Town Center businesses closed for months.
  • Memorial-Hermann’s new Town Center facility flooded just before it opened and is still under repair.
  • Kingwood and Deerwood Country Clubs flooded and still have not fully reopened.
  • Lone Star College/Kingwood lost 11 of its 13 buildings for most of the school year.
  • Kingwood High School closed for 7 months and underwent repairs costing $60 million.
  • 4000 students had to be bused to another high school an hour away for all that time.
  • Humble ISD closed its Instructional Support Center, Welcome Center and Agricultural Barns for repairs.
  • Tax revenues from the Lake Houston area were impacted by 20-30 percent according to City of Houston estimates.
  • Humble ISD had to give out tax rebates for the last third of 2017.
  • Kingwood’s library closed for more than eight months.
  • River Grove Park had to be excavated from sand up to five feet deep.
  • Kingwood’s only community boat launch became landlocked.

Harvey knocked out the Union Pacific Railroad Bridge over the San Jacinto, disrupting rail service for weeks. Picture taken Sept. 14, 2017.

TxDOT hopes to complete I-69 Bridge repairs in September, more than a year after Harvey. Picture taken May 13, 2018.

Causes for Concern

So, what caused all this devastation? Was it purely the magnitude of Harvey? Or are other factors at work?

Release Contributes to Flooding Far Outside 500-Year Flood Plain

First, the release of 79,000 cubic feet of water per second from Lake Conroe at the peak of Harvey made the flood worse. That volume represented about ONE THIRD of all the water coming down the heavily populated West Fork between Humble and Kingwood where most of the damage took place. This extra water flooded people and businesses outside the 500-year flood plain.

New Sand Deposits Back Up River and Drainage Ditches

Second, Harvey swept sand downstream, in part, from approximately 20 square miles of sand mines between I-45 and I-69. This sand blocked and backed up the river at strategic choke points. It also blocked drainage ditches leading to the river.

This massive sand bar grew 1500 feet in length and 12 feet in height during Harvey. It now blocks a drainage ditch (left center) that empties the western third of Kingwood. More than 650 homes flooded in neighborhoods that connect to this ditch.

Until dredging removes such deposits, Kingwood and Humble residents live in fear of every approaching storm.

Greater than Expected Flooding on Minor Rains

Third, even minor storms are causing much greater-than-expected flooding because of such blockages.

For example, a late-March storm this year dumped an average of five inches of rain across the watershed. It brought floodwaters two to three feet higher than a similar 5-inch rain at the beginning of last August – just before Harvey. Worse, the March flood happened AFTER Lake Houston had been lowered by 2 feet in anticipation of the storm.

Clearly, something has changed on the river. Because of massive sand deposits, such as those shown below, it won’t take another Harvey to cause significant damage.

This sandbar deposited during Harvey is an estimated 8 feet in height and stretches nearly the entire width of the river.

During Harvey, thousands of homes and businesses flooded behind blockages, such as this one, where the West Fork enters Lake Houston.

At West Lake Houston Parkway (left), Harvey deposited sand in the tree tops. Sand now blocks water from flowing under the bridge and through the trees during a storm as it did before, narrowing the effective width of the river considerably.

The U.S. Army Corps of Engineers is organizing a dredging project to address such problems and expects to start in June. Until they finish and redraw the flood maps after dredging, no one really knows how many homes would flood due to Lake Conroe releases, such as those we have seen in the last three years.

Artificial Bottleneck

A fourth factor also worries Kingwood residents – the dam on Lake Houston has only two small floodgates. Combined, they have one-tenth the release rate of Lake Conroe’s. This creates a bottleneck. It greatly inhibits the ability of officials on both lakes to coordinate releases of water before storms as a flood mitigation strategy.

Houston Mayor Sylvester Turner has committed to adding ten more gates to Lake Houston and Congressman Ted Poe has asked the U.S. Army Corps of Engineers to fast-track the project.

But still, the gates must be built – just as the river must be dredged. Until we fix these problems, thousands of downstream residents will not be able to sleep soundly at night. For them, this is about survival, not recreation.

The Only Immediate Option to Reduce Flood Risk

Lowering the level of Lake Conroe is the only option that will provide an immediate buffer against additional downstream flooding.

How much lowering is necessary? Is that extra foot really needed? If we got another storm as intense as Harvey, it would provide downstream residents only a two-hour buffer! That’s right. The storm would raise Lake Conroe that extra foot in just two-hours.

However, the two-foot reduction isn’t designed to protect against another Harvey. It’s designed to protect downstream residents against lesser floods that are abnormally high because of sand blockages like those shown above.

A two-foot reduction would let Lake Conroe absorb more water, decreasing the chances that SJRA would have to open flood gates. And if they had to open flood gates, it would delay the opening, giving downstream residents more time to evacuate.

The Lake Conroe Association will accept a one-foot reduction, but not two. That extra foot doesn’t seem like too much to ask, given all that’s riding on this decision for downstream residents as they still struggle to recover from billions of dollars in damages.

That buffer would also help protect the hundreds of Montgomery County homes that flooded around Lake Conroe and downstream from its dam.

Could another 500-year storm strike us this year? As unlikely as that seems, consider the fact that we’ve had three so-called “500-year storms” in the past three years. Something has changed out there affecting all of our assumptions. That’s why a little extra insurance would help.

Plea for Support

We ask our neighbors to the northwest for patience and support. Instead of lobbying against us, please join our fight. Help us expedite mitigation measures. With your support, our combined voices will bring change faster, so we can all return to normal life sooner.

Until then, we need to manage the river in a way that respects the lives and property of all residents on both sides of the dam, not just one.