Developing a Groundwater Regulatory Plan to Address Land Subsidence along the Texas Gulf Coast – The Harris-Galveston Subsidence District’s Approach to Mitigating the Problem

Bill Thaman, Freese and Nichols, Inc.10431 Morado Circle, Bldg 5, Ste 300, Austin, Texas 78759; and Michael Turco, General Manager, Harris-Galveston Subsidence District, 1660 West Bay Area Boulevard, Friendswood, Texas 77546,

Significant historical land subsidence, 6-10 feet in some areas, and about 13 feet in the Houston Ship Channel, have been measured in the Houston Area. Prior to World War II, groundwater use due to industrial and petrochemical development in the coastal cities of Baytown and Texas City were the primary contributors to subsidence. After World War II, as groundwater use dramatically increased to support rapid industrial and municipal growth in the Houston Area, subsidence became a regional issue. By the mid-nineteen-seventies, subsidence threatened residential subdivisions with total destruction from tidal flooding, and increased the flood risk for major elements of Houston’s economy including the Port of Houston, Ship Channel industries, industries in Baytown and Texas City, the Port of Galveston, NASA’s Johnson Space Center, the Texas Medical Center, and downtown Houston businesses.

The Texas Legislature created the Harris-Galveston Subsidence District in 1975 to stop subsidence in the Houston Area. The District first focused on the coastal areas since their lower elevations put them most at risk. The District’s 1976 Regulatory Plan established an Area of Concentrated Emphasis (ACE) which was based on elevations subject to hurricane tidal surges of 30 feet. Groundwater permittees in the ACE were required to review all options for reducing groundwater withdrawal. Cities and industries were largely cooperative and groundwater withdrawals were significantly reduced.

By 1992 the District had succeeded in stabilizing subsidence in most of the coastal areas, but subsidence rates were increasing in north and west Harris County. The 1992 Regulatory Plan expanded the area required to reduce groundwater usage to include all of Harris County while providing specific groundwater reduction targets. Starting with the 1999 Regulatory Plan, the District developed innovative regulations that allowed entities in Area 3 (north and west Harris County) to join into groups to collectively submit Groundwater Reduction Plans (GRPs) which would meet the District’s groundwater use goals with efficient, effective, and timely plans while also instituting a Disincentive Fee that would incentivize compliance with the District’s Regulations. Future district regulations will continue to help ensure the economic vitality of the greater Houston area well into the future, while protecting the region from the dangers of subsidence.

Key words: groundwater, regulations, subsidence, flooding

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