Texas Gulf Coast Groundwater and Land Subsidence

Forty Years of Research in the Houston-Galveston Region

In cooperation with Harris-Galveston Subsidence District, the City of Houston, Fort Bend County Subsidence District, Lone Star Groundwater Conservation District, and Brazoria County Groundwater Conservation District, the U.S. Geological Survey Texas Water Science Center Gulf Coast Program collects, processes, and interprets groundwater-level and aquifer-sediment-compaction data to understand the effects of groundwater withdrawal on land subsidence in the Houston-Galveston region, Texas.

Land Subsidence

Land subsidence is the gradual lowering of land-surface elevation. In the Houston-Galveston region, land subsidence is caused by compaction of fine-grained aquifer sediments (silts and clays) below the land surface due to groundwater withdrawals. Removing water from fine-grained aquifer sediments compresses the aquifer leaving less pore space available to store water resulting in the lowering (sinking or settling) of the land-surface. Most compaction that occurs as a result of groundwater withdrawals is irreversible; even if groundwater levels rise, compacted sediments and the associated land-surface lowering would remain as-is.

Consequences of land subsidence in the Houston-Galveston Region

  • Reduces the ability to store water in an aquifer.
  • Partially or completely submerges land.
  • Collapses water well casings.
  • Disrupts collector drains and irrigation ditches.
  • Alters the flow of creeks and bayous which may increase the frequency and severity of flooding.
  • Damages roadways, bridges, building foundations, and other infrastructure.

Groundwater Withdrawals

  1. 1836

    Groundwater Withdrawals Begin

    Primarly from the Chicot and Evangeline aquifers.

  2. 1975

    Groundwater Withdrawals Exceed 450 Million Gallons per Day

    Aquifer sediments begin compacting: about 3,200 mi2 subside more than 1 ft, some areas as much as 12-13 ft.

  3. 1977

    Extensive Groundwater Well-Monitoring Network established

    USGS collects water-level data to determine water-level decline from withdrawals.

  4. 1979

    First Water-Level-Altitude Maps of Aquifers Released

    Water-level altitudes declined as much as 250 ft (Chicot) and 350 ft (Evangeline).

  5. 2000

    Groundwater Withdrawal from Jasper Aquifer Increases

    Withdrawals increase as urban growth spreads northward.

  6. 2015

    Groundwater Levels
    Rise and Fall

    Groundwater levels rise: 100 ft (Chicot) and 200 ft (Evangeline). Groundwater levels decline: 100 ft (Jasper).

The three primary aquifers in the Gulf Coast aquifer system in the Houston-Galveston region are the Chicot, Evangeline, and Jasper, which are composed of laterally discontinuous deposits of gravel, sand, silt, and clay.

Groundwater withdrawn from the Chicot, Evangeline, and Jasper aquifers has been the primary source of water for municipal supply, commercial and industrial use, and irrigation in the Houston-Galveston region since the early 1900s.

Prior to 1975, the withdrawal of groundwater from the Chicot and Evangeline aquifers was unregulated, and water levels in the aquifers were declining with associated depressuring, dewatering, and compaction resulting in subsidence.

By 1977, the withdrawals had resulted in water-level altitude declines of 300 and 350 ft below datum in the Chicot and Evangeline aquifers, respectively, in southeastern Harris County, and correspondingly, by 1979, as much as 10 ft of subsidence had occurred in the Houston-Galveston region.

Explore Groundwater-Level and Compaction Data in the Chicot, Evangeline and Jasper Aquifers

USGS measures over groundwater levels in over 700 wells in an 11-county area annually in the Houston-Galveston area in order to develop a regional depiction of groundwater levels. The cumulative compaction in the Chicot and Evangeline aquifers are measured at 13 extensometer stations in the 11-county area.

Water-level altitude contours, wells, and compaction data have been combined in an interactive map that allows users to view annual water-level altitudes from 1977 through the present, water-level changes over time, and historical time series of compaction data.

Explore the Data

Looking for the raw data?

Groundwater-level and compaction data are available as part of USGS data products.

Get the Compaction Data Get the Water-Level Data Get the Latest Report

Regulatory Areas

To address the issues associated with land-surface subsidence and compaction, the 64th Texas State Legislature authorized the establishment of the Harris-Galveston Subsidence District to regulate and reduce groundwater withdrawals in Harris and Galveston Counties. Subsequent to establishing the Harris-Galveston Subsidence District, the Texas State Legislature established the Fort Bend Subsidence District and two groundwater conservation districts: Lone Star Groundwater Conservation District and, most recently, Brazoria County Groundwater Conservation District in the Houston-Galveston region to provide for the regulation of groundwater withdrawals in areas within their jurisdiction.

Harris-Galveston Subsidence District
1975: Established by Texas State Legislature.
1976: First regulatory area (Area of Concentrated Emphasis: ACE) established.
1985: Divided into 8 regulatory areas by amount of groundwater reduction needed.
1992: Regulatory areas redivided into 7 areas.
1999: Regulatory areas converted into 3 primary areas.
2013: HGSD regulatory plan updated.
Fort Bend Subsidence District
1989: Established by the Texas State Legislature.
2003: Regulatory areas divided into area A, which includes the Richmond-Rosenberg subarea, and area B.
Lone Star Groundwater Conservation District
2001: Established by the Texas State Legislature.
Brazoria County Groundwater Conservation District
2005: Established by the Texas State Legislature.

Regulatory areas from 1985 to 2016 shown on imagery from each corresponding year.

Data Processing and Map Creation

Since 1977, the USGS Texas Water Science Gulf Coast Program has published regional groundwater maps for the Houston-Galveston Region, Texas. After collecting and evaluating groundwater-level data for quality control, data are incorporated into a geographic information system (GIS) and used for the construction of regional water-level altitude and regional water-level change contour maps.

Regional water-level altitude maps were created by manually interpolating contours of water-level altitude data at observation wells in the Houston-Galveston Region. Water-level altitude is calculated at each well by subtracting the water-level measurement (depth to water below land surface) from the referenced well land-surface altitude. The accuracy of the referenced well land-surface altitude data has improved through time and the most accurate land-surface altitude data available at the time of publication were used in the creation of each regional water-level altitude contour map.

Regional water-level change contour maps were constructed by interpreting the compiled water-level altitude data as the difference in water-level altitude at each well for the water-level data collection year and the historical year or as the difference in water-level altitude at each well for the water-level data collection year and the interpolated water-level altitude of the historic year from a modeled surface. Interpolated modeled water-level altitude surfaces were only used to compute differences when wells were destroyed or were not measured during the individual publication study period. Further information detailing the data processing and map creation for each published regional water-level altitude and regional water-level change contour map can be found in the individual year publication.

Select USGS Publications

Water-Level Altitudes 2016 and Water-Level Changes in the Chicot, Evangeline, and Jasper Aquifers and Compaction 1973–2015 in the Chicot and Evangeline Aquifers, Houston-Galveston Region, Texas

Scientific Investigations Map 3365

By Mark C. Kasmarek, Jason K. Ramage, and Michaela R. Johnson

Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers...

Water-Level Altitudes 2015 and Water-Level Changes in the Chicot, Evangeline, and Jasper Aquifers and Compaction 1973–2014 in the Chicot and Evangeline Aquifers, Houston-Galveston Region, Texas

Scientific Investigations Map 3337

By Mark C. Kasmarek, Jason K. Ramage, Natalie A. Houston, Michaela R. Johnson, and Tiffany S. Schmidt

Most of the land-surface subsidence in the Houston-Galveston region, Texas, has occurred as a direct result of groundwater withdrawals for municipal supply, commercial and industrial use, and irrigation that depressured and dewatered the Chicot and Evangeline aquifers, thereby causing compaction of the aquifer sediments, mostly in the fine-grained silt and clay layers...

Estimated Land-Surface Subsidence in Harris County, Texas, 1915–17 to 2001

Scientific Investigations Map 3097

By Mark C. Kasmarek, Robert K. Gabrysch, and Michaela R. Johnson

Land-surface subsidence, or land subsidence, in Harris County, Texas, which encompasses much of the Houston area, has been occurring for decades. Land subsidence has increased the frequency and extent of flooding, damaged buildings and transportation infrastructure, and caused adverse environmental effects. The primary cause of land subsidence in the Houston area is withdrawal of groundwater, although extraction of oil and gas also has contributed...

Groundwater Withdrawals 1976, 1990, and 2000-10 and Land-Surface-Elevation Changes 2000-10 in Harris, Galveston, Fort Bend, Montgomery, and Brazoria Counties, Texas

Scientific Investigations Report 2013-5034

By Mark C. Kasmarek and Michaela R. Johnson

The study area comprising Harris County and parts of Galveston, Fort Bend, Montgomery, and Brazoria Counties in southeastern Texas forms part of one of the largest areas of land-surface-elevation change in the United States. Land-surface-elevation change in the study area primarily is caused by the withdrawal of groundwater. Groundwater withdrawn from the Chicot and Evangeline aquifers has been the primary ...

Investigation of Land Subsidence in the Houston-Galveston Region of Texas by Using the Global Positioning System and Interferometric Synthetic Aperture Radar, 1993–2000

Scientific Investigations Report 2012-5211

By Gerald W. Bawden, Michaela R. Johnson, Mark C. Kasmarek, Justin Brandt, and Clifton S. Middleton

Since the early 1900s, groundwater has been the primary source of municipal, industrial, and agricultural water supplies for the Houston-Galveston region, Texas. The region’s combination of hydrogeology and nearly century-long use of groundwater has resulted in one of the largest areas of subsidence in the United States; by 1979, as much as 3 meters (m) of subsidence had occurred, and approximately 8,300 square kilometers of land had subsided more than 0.3 m...

Hydrogeology and Simulation of Ground-Water Flow and Land-Surface Subsidence in the Northern Part of the Gulf Coast Aquifer System, Texas

Scientific Investigations Report 2004-5102

By By Mark C. Kasmarek and James L. Robinson

As a part of the Texas Water Development Board Ground-Water Availability Modeling program, the U.S. Geological Survey developed and tested a numerical finite-difference (MODFLOW) model to simulate ground-water flow and land-surface subsidence in the northern part of the Gulf Coast aquifer system...

Principal Faults in the Houston, Texas, Metropolitan Area

Scientific Investigations Map 2874

By Sachin D. Shah and Jennifer Lanning-Rush

This report, prepared by the U.S. Geological Survey in cooperation with the Harris-Galveston Coastal Subsidence District, documents and refines the locations of principal faults mapped in the Houston, Texas, metropolitan area in previous studies. Numerous subsurface faults have been documented beneath the Houston metropolitan area at depths of 3,200 to 13,000 feet...

Evaluation of Ground-Water Flow and Land-Surface Subsidence Caused by Hypothetical Withdrawals in the Northern Part of the Gulf Coast Aquifer System, Texas

Scientific Investigations Report 2005-5024

By Mark C. Kasmarek, Brian D. Reece, and Natalie A. Houston

During 2003-04 the U.S. Geological Survey, in cooperation with the Texas Water Development Board (TWDB) and the Harris-Galveston Coastal Subsidence District (HGCSD), used the previously developed Northern Gulf Coast Ground-Water Availability Modeling (NGC GAM) model to evaluate the effects of hypothetical projected withdrawals on ground-water flow in the northern part of the Gulf Coast aquifer...

Land Subsidence in the United States

Circular 1182

By Devin Galloway, David R. Jones, and S.E. Ingebritsen

Land subsidence is a gradual settling or sudden sinking of the Earth's surface owing to subsurface movement of earth materials. Subsidence is a global problem and, in the United States, more than 17,000 square miles in 45 States, an area roughly the size of New Hampshire and Vermont combined, have...

Ground-Water Withdrawals and Land-Surface Subsidence in the Houston-Galveston Region, Texas, 1906-80

Open-File Report 82-871

By R.K. Gabrysch

The withdrawal of large amounts of ground water in the Houston-Galveston region, Texas, has resulted in water-level declines of as much as 250 feet (76 meters) in wells completed in the Chicot aquifer and as much as 300 feet (91 meters) in wells completed in the Evangeline aquifer during 1943-77...

Approximate Water-Level Changes in Wells in the Chicot and Evangeline Aquifers, 1977-81 and 1980-81, and Measured Compaction, 1973-81, in the Houston-Galveston Region, Texas

Open-File Report 81-341

By R.K. Gabrysch and C.E. Ranzau, Jr.

Illustrations of water-level changes in wells.

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