Harris and surrounding counties are slowly sinking because of subsidence. Subsidence is the motion of the earth's surface as it shifts downward, or sinks, relative to the sea level. This is happening here because we are using too much underground water from our sponge-like ground.

Subsidence along with other factors makes Houston and the surrounding area extra susceptible to flooding. That is why the House Committee on County Affairs, which I chair, is looking into this issue during this interim. At our last hearing in Austin on May 10th, the Committee heard from Michael J. Turco, the General Manager of the Harris-Galveston Subsidence District (HGSD). You can view his presentation by clicking here, and you can watch his testimony starting at the 3:53 mark by clicking here.

According to the Harris-Galveston Subsidence District, some parts of Harris County have sunk 10 feet since 1906. The problem is also happening rapidly now in some areas such as in the Greater Greenspoint area, which has sunk about 2 feet in the last decade alone, according to United States Geological Survey (USGS) data. Mark Kasmarek, a hydrogeologist for more than 30 years with the USGS says, “When you lose that much, it makes an area prone to floods when they weren't historically.”

The Harris-Galveston Subsidence District, created in 1975, has been effective at slowing the subsidence rates in the areas it regulates. Instead of losing a foot every 10 years, many areas saw that rate cut by a little more than two-thirds. However, more needs to be done to fix the problem because once an area sinks it is very hard to build it back up and the occurrence of flooding increases. That is why the Committee and I will look into both statewide and local solutions to better educate the public, increase groundwater conservation, converge to alternative sources of water, and build additional reservoirs.

I will continue to keep you updated on this important issue as the County Affairs Committee studies it during the interim. The Committee’s next hearing will be in Corpus Christi on Tuesday, June 6th. The Committee will once again discuss Hurricane Harvey and the damage it caused particularly by wind damage to the coastal bend region.

According to the HGSD, from 1978 to 2000, as much as 5 feet of subsidence has been measured in northwest Harris County. This is demonstrated in the map above.