Recently released subsidence maps show that excessive groundwater pumping in Montgomery County could lower the northern end of Lake Houston by two feet or more relative to the spillway at the southern end of the lake. While subsidence would lower the area near the spillway by a foot, it would lower areas near the county line even more – from 3 to 3.25 feet.
Subsidence Estimates are Conservative
And those estimates are conservative because:
- Models under-predict subsidence; they currently model nothing from the Jasper Aquifer, which Quadvest, a MoCo water supplier, wants to pump heavily from (see more below).
- Montgomery County factions are threatening legal action to let them pump more than their counterparts in the 15-county Groundwater Management Area #14 (GMA14) think is safe.
So how did we get to this point?
Groundwater Vs. Surface Water
The rest of the world is trying to convert to surface water to avoid subsidence. However, Simon Sequeira’s family-owned business, Quadvest, still pumps much groundwater in Montgomery County. He’s at war with the world. While others recognize subsidence and the science behind it, Sequeira denies it’s a problem – at least in Montgomery County.
At the last GMA14 meeting, lawyers were reportedly lining up to get a piece of his action and licking their lips.
Broken Promises And Legal Battles
Several years ago, Sequeira led a fight to get the board of the Lone Star Groundwater Conservation District elected rather than appointed. Then he backed candidates who favored unlimited groundwater pumping and promised to Restore Affordable Water.
While groundwater is cheaper than surface water, water bills reportedly failed to come down. However, he has stopped paying the SJRA a fee designed to encourage conversion from groundwater to surface water. Sequeira says he is setting aside that money in a special fund in case he loses his legal battle. But his legal battles go far beyond the SJRA. He and the board of the Lonestar Groundwater Conservation District are also taking on the rest of GMA14. See map below.
Purpose of Groundwater Management Areas
GMA stands for “Groundwater Management Area.” GMAs were set up years ago, in part, to make sure that one county doesn’t hog groundwater, depriving surrounding areas and creating subsidence. So the other counties in GMA14 get to approve (or not) the groundwater withdrawal rates in Montgomery County.
They do that by defining “desired future conditions.” How much drawdown in an aquifer is acceptable? How much subsidence can people and infrastructure tolerate?
GMA14 wants Sequeira to leave 70% of the water in aquifers intact and to produce no more than 1 foot of subsidence. But the pumping levels proposed by Sequeira would produce far more subsidence, according to GMA14.
Hired-Gun Experts Defy Scientific Consensus
Ever since, Sequeira took on this fight, his hired-gun experts have been trying to prove subsidence doesn’t pose a threat in Montgomery County. Unfortunately, data and models don’t agree with him. His pumping has already created subsidence in MoCo and now threatens northern Harris County, too.
Strangely enough, while science has shown – and the rest of the world believes – that unlimited groundwater pumping causes subsidence, Sequeira does not. His profit margin depends on cheap groundwater, unfettered by fees designed to encourage people to convert to surface water.
Five Alternative Plans Considered
Sequeira and company originally proposed three alternative plans to GMA14 that involved pumping enough groundwater to cause:
- 900 feet of decline in the Jasper Aquifer
- 700 feet of decline in the Jasper Aquifer
- 250 feet of decline in the Jasper Aquifer (Similar to “Run D” scenario, modeled below.)
Of those three, GMA14 only considered the last. GMA14 also came back with two more scenarios. They involved pumping even less groundwater:
- 115,000 acre-feet per year (Also similar to Lone Star’s “Run D” scenario. See below).
- 97,000 acre-feet per year
- 61,000 acre-feet per year
Note: Lone Star and GMA14 use different criteria to describe the volume pumped. GMA14 uses acre-feet-per-year instead of feet-of-decline in a specific aquifer. Nevertheless, experts say Sequeira’s last scenario is roughly comparable GMA14’s first.
The two sides are still arguing about how much can be pumped safely. And that’s why the lawyers are drooling.
Models Show Unacceptable Subsidence from Sequeira’s Least-Damaging Plan
Subsidence can alter the landscape in ways that cause water to collect in areas that otherwise might not flood. The maps below model projected subsidence in south Montgomery and northern Harris Counties. And we know that this model under-predicts subsidence. That’s because it doesn’t model ANY subsidence from the Jasper aquifer.
Sequeira’s least-damaging plan would cause up to 3.25 feet of subsidence in southern Montgomery County and up to 3 feet in northern Harris County, according to GMA14. See below.
Effect on Humble, Kingwood, Atascocita, Huffman Areas
If you live in the Lake Houston Area and you stare at that last subsidence map long enough, eventually you will come to a jaw-dropping realization.
Homes and businesses in the headwaters of Lake Houston will be lowered 2 feet relative to the spillway.
That’s a huge amount. Those who built homes a foot above the hundred year flood-plain could find themselves a foot below it. Those who had a couple inches of water in their homes during Harvey could have more than two feet in a similar future event because of subsidence.
Battle Lines Drawn
So the battle lines are drawn. Sequeira wants to allow up to 900 feet of decline in the Jasper aquifer. And GMA14 wants no more than 1 foot of subsidence with 70% of the aquifer intact. That would mean pumping less than 100,000 acre feet per year.
The presence of so many lawyers in the last GMA14 meeting reportedly has the smaller groundwater management districts nervous. One observer used the word “intimidated.” Some don’t have financial resources to fight Sequeira.
And that should make every homeowner in the Lake Houston Area nervous, too.
Posted by Bob Rehak on 11/22/2020
1181 Days since Hurricane Harvey
The thoughts expressed in this post represent opinions on matters of public policy and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas