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July 25th, 2024
Via The Texas Tribune, a look at how overdevelopment in Texas,and the rules that encourage it, could literally sink communities such as Katy, where the land is subsiding due to groundwater extraction:
Longhorns used to graze across the street from the house where Ozzy Tirmizi settled with his family in Katy, a western exurb of Houston. He grew up in southern Pakistan, but his dad’s job in oil and gas brought them to Texas in 2011, when Tirmizi was eighteen. Over the following decade, he watched as pastureland was paved over. Strip malls replaced the grass, and the bovine neighbors disappeared.
In 2019, Tirmizi entered a doctoral program in geology at the University of Houston. He learned to measure changes in ground elevation by using data from orbiting satellites and started working with a professor who studied subsidence, the gradual sinking of land. Tirmizi grew curious about whether the phenomenon was playing out in Katy. “I figured with how much development is happening,” he says, “that there’s probably some accelerated rates of subsidence.”
He was right. Greater Houston has some of the highest subsidence rates in the United States; within that region, parts of Katy are sinking faster than anywhere else, up to 1.4 centimeters a year since 2017. This is the result of so much groundwater being pumped for the thirsty new subdivisions that have sprouted in former rice fields and cow pastures along Interstate 10 and Texas Highway 99, known as the Grand Parkway.
Subsidence makes visible the hidden crisis of groundwater depletion. Subterranean water in the state is governed by the rule of capture, which allows landowners to draw as much from beneath their property as they wish, regardless of the impact on the supply of water for others. That principle was established in a 1904 court case, long before the advent of large-scale pumping of water from aquifers for agricultural and residential use. “Texas has never wanted to recognize that it is short of water,” says Jim Blackburn, an environmental law professor at Rice University. “The Texas mindset has always been come and take it—come and take our resources.”
Water levels in the Gulf Coast Aquifer, which spans 41,000 square miles from the Texas-Louisiana border to Mexico, have declined in the Houston region by as much as 150 feet since 2000. (Across the aquifer, fresh water extends to an average depth of 1,000 feet.) Because most of that water is contained in layers of clay, sand, and silt—unlike, for example, the honeycomb limestone that defines the Edwards Aquifer under Austin and San Antonio—Houston is particularly susceptible to subsidence. As water is extracted, the Gulf Coast’s softer soil layers compress, and the land sinks.
The first sign of subsidence is standing water, which pools in gentle depressions. That’s already happening in Katy, Tirmizi says. Infrastructure damage comes next. Cracks and fractures will start appearing on roads and buildings, typically along the fault lines that cut across the city. Because subsidence causes those faults to reactivate, “you’ll have one side that’s sinking, one side that’s stable,” Tirmizi says. “That differential stress is what causes infrastructure damage.”
About halfway between Katy and downtown Houston, subsidence is visible in the neighborhood of Spring Branch West, where the Long Point Fault cuts northeast through the intersection of I-10 and Beltway 8. Moorhead Drive drops abruptly at one point, with houses on either side slanting downhill. The fault continues along Westview Drive, where Fernando Toro has lived for a decade. He’s watched as the homes around his have flooded and his neighbors have replaced their foundations. His house sits atop three feet of concrete. “That’s why I bought it, because it has a good foundation,” he says.
Subsidence isn’t a new problem. The Houston area has been sinking for more than a century because of both groundwater pumping and oil extraction. By the seventies, some parts of Harris County had sunk by more than seven feet in three decades, according to data from the U.S. Geological Survey. In 1975 the Texas Legislature created the Harris-Galveston Subsidence District to regulate groundwater use. Eventually the district required water providers to transition away from drawing upon the aquifer and instead tap surface water from a variety of sources, including Lake Houston, a reservoir on the San Jacinto River. As the City of Houston shifted to using more surface water, the land steadied.
But Katy, as well as most of Greater Houston, still relies on groundwater. As development spreads west, so does the sinking.
Katy sits in the middle of what was once a vast coastal prairie that covered more than nine million acres. A 1945 photo taken by the Texas Land Office shows a small townsite (population 800) surrounded by tidy farms, rice fields, and, beyond, an expanse of tall, wild grasses pockmarked by ponds. Over the decades, as Houston boomed, the prairie was absorbed by suburban sprawl. Today 383,000 residents live within the boundaries of Katy’s school district, which serves the city and several surrounding communities. Between 2013 and 2022, the amount of land in the area that’s been covered by houses or businesses or roads or parking lots has almost doubled.
That development didn’t happen by accident. In 2008 the Texas Department of Transportation completed a $2.8 billion expansion of the Katy Freeway to 26 lanes in some sections, making it one of the widest highways in the world. A year later the agency approved the construction of a fifteen-mile stretch of road dubbed the Grand Parkway, that will eventually become a 180-mile loop around Houston, traversing seven counties.
“The Grand Parkway opened up the Katy Prairie,” says Mary Anne Piacentini, the president and CEO of the Coastal Prairie Conservancy, which seeks to protect and restore the Katy Prairie and coastal wetlands. “Development follows roads,” she adds, paraphrasing the late J.?B. Jackson, an acclaimed writer on architecture and landscapes. “Roads don’t follow development.”
The Katy Prairie long acted as a natural sponge during heavy rainfall, as deep-rooted grasses and ponds absorbed rainwater and held back floodwaters. No longer. During Hurricane Harvey, all that new pavement shed the rainwater and sent it rushing downstream into Houston.
The Coastal Prairie Conservancy protects 19,000 acres of the Katy Prairie, through either direct ownership or conservation easements. The value generated by this land is twofold—every acre held in conservation helps protect Houston from flooding and prevents new development from pumping more groundwater. “The same threats that we had twenty-five years ago are pretty much what we’re facing now,” says Wesley Newman, the nonprofit’s conservation director. “Except now, they’re much more imminent because they’re right down the street.”
By threats, Newman means houses and people. The conservancy’s 3,100-acre Indiangrass Preserve, fifteen miles northwest of Katy, will soon be surrounded by subdivisions. These developments have idyllic names such as Grand Prairie, Lakeview, and Mallard Crossing. “They name them after what they’ve destroyed,” Newman says. The land has been fenced and parceled into lots, with blue and gray two-story houses along concrete roads.
All of these neighborhoods will use groundwater. In Harris, Galveston, and Fort Bend Counties, developers must get approval from the Harris-Galveston Subsidence District to pump, but the district rarely denies it. Permit applicants must commit to eventually converting to surface water, but most of the growth in the Katy area is in Waller County, where there is no such requirement. “There’s no subsidence district there,” says Michael Turco, the Harris-Galveston Subsidence District’s general manager. “There’s no groundwater regulation.”
To turn open prairie into a subdivision, most developers will apply to the Texas Commission on Environmental Quality to form a Municipal Utility District, or MUD. Creating such a district grants developers governmental authority to finance the building of water wells and pipes, among other infrastructure. Through a MUD, a developer can borrow the necessary money and levy a property tax or charge user fees to pay the debt.
Greater Houston is home to more than 370 MUDs, spanning four hundred square miles and representing a population of 1.5 million people. This is what’s causing subsidence, according to Blackburn, the Rice environmental law professor. “These districts have been formed to implement a philosophy of unregulated development,” he says. “You don’t have to wait for the City of Houston to expand utilities to you.”
The problem isn’t unique to Texas—last year, the New York Times analyzed data from tens of thousands of groundwater-monitoring wells nationwide and found that nearly half had “declined significantly” over the past four decades, in part because there is almost no regulatory oversight. But most states have moved away from the rule of capture. No other Western states still adhere to it. “Among major groundwater users,” concluded a 2021 report from Rice and Texas State University, “Texas is an outlier.”
Here property owners have an unparalleled right to pump, even when their pumping harms others. A decade ago, an appeals court ruled that the Edwards Aquifer Authority had violated the property rights of two San Antonio farmers when it restricted how much water they could draw from beneath their land. Now “groundwater districts [are] so afraid of being sued that they’ll give everybody a permit that walks in the door,” says Robert Mace, the executive director of the Meadows Center for Water and the Environment, at Texas State. “Subsidence districts allow this groundwater pumping to occur, and then once this land subsidence starts to be an issue, then they push to convert to surface water. . . . And that can be controversial because surface water is a hell of a lot more expensive than groundwater.”
That’s exactly how the situation has played out in Katy. In 2020 construction began on a pipeline that will eventually carry 151 million gallons of water per day 55 miles from Lake Houston to Katy and Fort Bend County. (For comparison, the City of Houston treats 472 million gallons of water daily.) The pipeline is projected to cost more than $1 billion, mostly paid for by fees on residents’ monthly water bills.
Lake Houston water won’t reach Katy until at least 2028. Katy city engineer David Kasper eagerly awaits its arrival. “From our perspective, the concern to some degree is subsidence,” he said. “But the aquifer level is the bigger concern.” Since 2018, groundwater levels in the portion of the Gulf Coast Aquifer beneath Katy have dropped by nearly seventy feet, according to federal data. “It’s just an order of magnitude worse, not having any water.”
When will the groundwater run out? It’s unclear. In the artesian aquifers under Houston, water is confined under pressure, below impermeable clay. Sink a well and that pressure will push water to the surface. “Once we bleed out the artesian pressure, it gets a lot more difficult to get that water out,” Mace says. “The viability of producing these large amounts of water that folks are either producing now or plan to produce, is going to dry up long before the aquifer dries up.”
When the Texas Supreme Court established the rule of capture, it called the existence and movement of underground water “so secret, occult, and concealed that an attempt to administer any set of legal rules in respect to them would be involved in hopeless uncertainty, and would, therefore, be practically impossible.” Today we can measure and track groundwater in minute detail, and yet the rule of capture remains. “It is a very, very poor concept for water management,” Blackburn says. “It’s just this disbelief in science.”
Absent legislative action, Blackburn argues, the Texas Supreme Court will eventually have to overturn the rule of capture. Scarcity will force regulation. Last summer, facing an “unprecedented” demand for water, Katy issued mandatory restrictions, significantly limiting outdoor water use, even as new lawns and pools sprouted in MUDs outside the city limits.
Last year, Tirmizi and his professor, Shuhab Khan, copublished a paper in the journal Remote Sensing concluding that population growth and high rates of groundwater extraction had caused Katy to start sinking. They expect to see infrastructure damage in the city over the coming decade. Tirmizi’s family home sits in the middle of an “intensifying hot spot” identified in the paper.
Khan often hears from Greater Houston homeowners who have seen cracks in their foundations, asking for his help to determine the cause. He published an interactive map online of subsidence hot spots. But it’s a sensitive subject. Public officials don’t like hearing their districts are sinking. “Sometimes,” Khan says, “they say, ‘You are scaring people.’?”
Still, he loves the work. Geological research doesn’t often affect people’s lives, because tectonics evolve slowly. “Here the impact is immediate,” Khan says. “It’s helping people. This is so fast. You pump water, here is the motion. Here is the fault activated.” If you knew your land were sinking, he asks, wouldn’t you want to do something about it?