LOSING GROUND Katy, one of the fastest-growing suburbs, showed the second highest rate of land depression in the Houston area from March 2016 to December 2020. The appearance of new hot spots in the southwest quadrant of the city in 2020 suggests statistically signi cant subsidence, according to the University of Houston report. They also coincide with Katy’s newest groundwater wells.
occurred,” he said. “But for the most part, land sub- sidence is a one-way trip. Once it’s compressed, it’s not coming back up.” Study ndings The UH report found the Katy area’s population growth, development and geological characteristics a ect subsidence, but the biggest contributor was the use of groundwater from aquifers. Wells can be drilled into an aquifer, a large, underground water-bearing rock, and water can be pumped out for use by residents of a city. Khan’s report analyzed subsidence data in the Houston region from 2016-21. “This [is happening] all over Katy,” Khan said. Data from the Harris-Galveston Subsidence Dis- trict, which regulates groundwater and monitors subsidence in Harris and Galveston counties, sup- ports the study’s ndings. The UH report also measured groundwater levels below the surface of Katy and other Houston suburbs from 1990-2021. The aquifer water level was around 65 meters below the surface in 1990, compared to 110 meters below ground in 2021. Even further, the report pinpointed new hot spots of subsidence in the southwest quadrant of the Katy area, coinciding with one of the city’s seven water wells in Waller County. The city’s 2021 drinking water report states the water wells have a combined storage capacity of 7.25 million gallons. Ashley Greuter, director of research and water conservation for the HGSD, con rmed GPS data indicates the impacts of compaction in the aquifer associated with groundwater development. In the past four years, mapping data from the HGSD found a 6.8-centimeter depression in the same location as the Waller County water well. HGSD General Manager Mike Turco said the Katy area is experiencing subsidence because it has seen population increases and continued develop- ment, which leads to more groundwater pumping to meet water needs in the area. Between 2011-20, the six ZIP codes that make up Community Impact’s coverage area—77449, 77493, 77494, 77441, 77450 and 77094—saw a 57.31% population increase from 246,673 to 388,036, according to U.S. Census Bureau data. The Katy Area Economic Development Coun- cil expects 41,466 more residents to join Katy
CENTIMETERS OF DISPLACEMENT
WEST RD.
-0.45 to -0.20 -0.20 to -0.10
-0.10 to -0.00
-8.97 to -2.75 -2.75 to -2.45
-2.45 to -1.75 -1.75 to -1.25
-1.25 to -0.85 -0.85 to -0.45
FREEMAN RD.
529
W. LITTLE YORK RD.
99
2855
CLAY RD.
MORTON RD.
6
FRANZ RD.
KATY RD.
90
10
10
KINGSLAND BLVD.
1463
N
LOWER LEVELS Studies also found a consistent decline in the aquifers' water level from 1990 to 2021 and the potential reactivation of faults around Katy. All of these factors point to the sinking of the city, experts said.
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susceptible to ooding. Katy City Engineer David Kasper said the city is looking for ways to reduce the area’s reliance on groundwater, and while the city plans to take advantage of alternative sources, these options will not become available until 2026 at the earliest. “We expect to receive surface water sometime between 2026 and 2028, thus reducing our use of groundwater supplies,” he said. Though the conditions that cause subsidence can be lessened by cities using alternative sources, such as surface and potable water, the e ects of subsid- ence are permanent, said Robert Mace, water policy director at Texas State University. “If you reduce your pumping, you can then decrease the maximum subsidence that would have
WATER LEVEL BELOW SURFACE IN METERS
0 20 40 60
100 120 80
1990 1995 2000 2005 2010 2015 2020
SOURCES: MDPI, REMOTE SENSING JOURNAL, CITY OF KATY, 2021 ANNUAL DRINKING WATER QUALITY REPORT COMMUNITY IMPACT
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