Is The Ground Falling? Should We Care? Part 3 of 4: SJRA General Manager Jace Houston explains subsidence science, history

Is The Ground Falling? Should We Care? Part 3 of 4: SJRA General Manager Jace Houston explains subsidence science, history

Image: This patriotic chicken has nothing whatsoever to do with this article, except that several readers of The Golden Hammer have commented that they’ve enjoyed the chickens shown during this four-part series on subsidence. Part 1 of the series did, however, begin with references to the story of “Chicken Little,” “Kylling Kluck,” or “Henny Penny,” all of which likely derive from an oral tradition, which Just Mathias Thiele first put in print in a collection of Scandinavian tales in 1823.

“In the water business, we have to look 50 to 100 years in the future.” – – Jace Houston, General Manager, San Jacinto River Authority

Conroe and all of Montgomery County, July 5 – Subsidence is real in Montgomery County and the pumping of groundwater is a major cause, according to Jace Houston, General Manager of the San Jacinto River Authority (SJRA).

Houston and Heather Ramsey Cook, SJRA’s Director of Communications and Public Affairs, presented the science and history of subsidence to this newspaper during a lengthy interview on June 25, 2019. Both Houston and Cook were extremely generous with their time and information and seemed eager to provide the data and analysis. Despite this newspaper’s criticism of SJRA and of Houston, Houston has always maintained a cordial relationship with The Golden Hammer and the newspaper’s staff.

In addition to answering questions during the interview, Houston and Cook provided over 400 pages of material and data to this newspaper for this article, so, obviously, this article merely summarizes the wealth of information SJRA made available.

The San Jacinto River Authority has the duty and authority in the watershed of the San Jacinto River north of the Harris County line to provide flood control, control soil erosion, and to impound water for to municipalities, industries, and agriculture, among other duties. The Texas Legislature created the state agency in 1937. The watershed of the San Jacinto River includes, among other areas, all of Montgomery County.

San Jacinto River Authority General Manager Jace Houston.

Whether one agrees with some of his opinions or not, there is no denying that Jace Houston is a remarkable individual with a remarkable background. He’s articulate and very intelligent. He is an attorney with his Juris Doctor and Bachelor of Science in Civil Engineering degrees from the University of Texas at Austin. He served as general counsel for the Harris-Galveston Subsidence District, staff attorney for the Texas Natural Resource Conservation Commission, and general counsel for State Representative Robert Saunders in the Texas House of Representatives. He joined SJRA in 2007 and became its General Manager in 2012.

It’s important to have a general understanding of the stratigraphy of the Gulf Coast area. Here it is.

Gulf Coast stratigraphy and aquifers. Source: United States Geological Survey.

The surface formation in Montgomery County is the Chicot Formation, a Pleistocene sandstone formation. As the stratigraphic section suggests, most of the groundwater production in Montgomery County comes from the Chicot, Evangeline, and Jasper aquifers.

“A substantial groundwater level decline and subsidence has been happening in the Greater Houston region since the early 1900s,” Houston explained. “As more people and industries pump more groundwater, we began to see subsidence.”

Houston said that observations of significant subsidence began in the 1940s and 1950s. “Subsidence follows population and high groundwater demand areas, such as along the Ship Channel where we’ve seen a lot of it,” he explained. “In the 1975 time frame in the Greater Houston Area, we saw really serious subsidence amounts and saw a lot of lowering of elevation.”

This map consists of an accumulation of data from 1906 to 2016 showing the extent of subsidence in feet throughout the Greater Houston area. Source: Houston-Galveston Subsidence District.

The map, which the Harris-Galveston Subsidence District prepared (immediately above), is significant. It shows between two and three feet of subsidence in the southern parts of Montgomery County from east to west. As one moves south, the extend of subsidence over the past century has increased up to ten feet just north of the Pasadena area. The central part of Houston has subsided six feet since 1906.

If you question the source of the above map, a much clearer depiction of subsidence comes from a United States Geological Survey (USGS) study, which the Lone Star Groundwater Conservation District (LSGCD) has made available on its website, which also shows substantial subsidence, one to two feet, in Montgomery County and the Greater Houston area since 1915. That map follows.

Source: United States Geological Survey (available through Lone Star Groundwater Conservation District website.)

The USGS results are similar to those depicted in the map above from the Harris-Galveston Subsidence District. The two maps arise from slightly different methodologies.

Houston explained, “The groundwater level decline and pattern of groundwater pumping led to the formation of the Harris-Galveston Subsidence District, which is a groundwater conservation district similar to our own [Montgomery County’s] Lone Star Groundwater Conservation District. They began managing how much groundwater users could pump in order to prevent subsidence, because, in the Houston area, pump age has been high everywhere where there has been relatively high population density.”

The Texas Legislature created the Harris-Galveston Subsidence District (HGSD) in 1975 at the request of Houston area business and political leaders. HGSD describes its own history as follows:

“In the 1950’s and 1960’s, community leaders finally began to link the increased frequency and severity of flooding to subsidence. In the sub-tropical, low-lying areas of Houston/Galveston — where tropical storms and hurricanes were a probability, not just a possibility– flooding was real and could be severe. In 1961, when Hurricane Carla hit, our worst fears about the impact of subsidence were confirmed. The storm had been horrific and some water damage was not surprising, but the flooding that occurred was beyond what was, in the past, expected from a hurricane of this size. As a result, local area governments began to analyze the serious and very real impact subsidence could have on the area’s potential economic growth and quality of life, and, just as important, began to determine what exactly could be done about it.

“With a number of studies linking groundwater withdrawal to subsidence — and ongoing measurements confirming those findings — groups of citizens began to work for a reduction in groundwater use in the late 1960’s. By 1973, the City of Galveston had begun converting to surface water supplied from Lake Houston, and in May of 1975, the Texas Legislature created the Harris-Galveston Subsidence District (HGSD), the first of its kind in the United States. Authorized as a regulatory agency created to “end subsidence” and armed with the power to restrict groundwater withdrawals, the Subsidence District immediately went to work on a plan to positively impact the critical situation in the coastal areas.

“By 1976, the District had begun the process of compiling hydrologic information on the characteristics of the Chicot and Evangeline aquifers, engineering planning information on water usage and water supply in Harris and Galveston counties, and implementing regulatory procedures associated with their first groundwater regulatory plan. By converting industries on the Houston Ship Channel to surface water supplied from the recently completed Lake Livingston reservoir, subsidence in the Baytown-Pasadena area was dramatically improved, and has since been largely halted.

“But as subsidence was stabilizing in the coastal areas, groundwater levels in inland areas north and west of Houston were rapidly declining. In the Evangeline aquifer, measurements recorded a decline of more than 100 feet between 1977 and 1997.

“As a result of the increasing threat subsidence posed to these areas, the HGSD adopted a series of regulatory plans to reduce groundwater pumpage, and ultimately mandated, in their 1999 plan, a reduction to only 20% reliance on groundwater by 2030. With the help of the North Harris County Regional Water Authority (NHCRWA) and the West Harris County Regional Water Authority (WHCRWA), both created by the Texas Legislature to transition the areas to surface water in the allotted timeframe, a fair and equitable contract with the City of Houston to supply surface water from Lake Houston was successfully negotiated and construction is already underway in both Authority areas. It is our goal that the same dramatic improvements will occur in these areas as were experienced south and east of Houston years ago.”

Houston and Cook explained that the Texas Legislature created a Fort Bend Subsidence District in 1989 to address many of the same regional problems.

Clearly, Jace Houston is not a lone wolf in the chicken coop in his conviction that groundwater withdrawals link to subsidence in the Greater Houston region.

At the Lone Star Groundwater Conservation District (LSGCD) Town Hall meeting on April 22, 2019, at the Woodlands Community Center, numerous allies of SJRA and the Woodlands Joint Power Agency (WJPA) attended and argued that subsidence is very real and that groundwater withdrawals are the cause. In fact, much of the discussion among surface water proponents, who urge more restrictive regulation of groundwater production, has focused on south Montgomery County, both in the southeast and south-central areas.

Houston, however, noted that data reveals that subsidence has occurred in many parts of Montgomery County other than merely the south.

Subsidence measurements at Texas Department of Transportation site near Montgomery County Airport north of Loop 336 in Conroe. Source: Texas Department of Transportation.

“There has been more than 6 inches of subsidence at the Montgomery County Airport area just in the last fourteen (14) years,” Houston said. “The borehole extensometer [a device which allows for measurements of precise longitudinal displacements in rock or soil masses] measurements of the geologic structures in the Conroe area are able to distinguish which portions of the aquifer have changed their positions.”

Houston explains, “The compaction occurs at depth.” Nevertheless, there clearly are signs of substantial subsurface movement which erupt at the surface.

One of the most dramatic examples of that subsurface movement is the Panther Branch Fault, which is visible in the parking lot of The Woodlands High School. In the parking lot, according to Houston (and as this newspaper confirmed on Tuesday, July 2), the fault “seems to curve and end, but actually extends north of Research Forest Drive.” Houston believes that much of the growth faulting which has occurred in The Woodlands emanates from subsidence.

A famous example of growth faulting, subsidence, and the relationship to groundwater production is the home of Woodlands Township Chairman Gordy Bunch in Carlton Woods, a beautiful gated neighborhood in The Woodlands. Bunch, who besides being the “People’s Chairman” as Township Board Chairman is also a gifted and highly successful businessman, said on social media three days ago, “It’s real and has been a major issue in Houston for decades. Becoming an issue in our area as well. My house sits on an active ground fault which moves or subsides more with groundwater or water table reductions. It will subside regardless but it is at a faster pace when water tables lower.”

SJRA’s Houston commented that the rate of subsidence and growth faulting, in particular, in The Woodlands seems to have declined during the past five years, because, he believes, groundwater production regulation has reduced the stress on the Chicot, Evangeline, and Jasper aquifers.

Houston has expressed surprise at those who have questioned whether subsidence is occurring, especially among individuals politically involved with LSGCD and its Board. “The whole debate that subsidence is not real issue is particularly surprising to me. The data is maintained by them,” Houston said, referring to LSGCD.

“The real question they ought to be asking is how severe the problem is. I’ve been arguing we have a groundwater production problem. It’s a water supply problem from my perspective. We lose well performance every time we have to lower pumps. The more we have to lift water out of groundwater wells is the more expensive that water production becomes,” Houston explained.

“Subsidence is clearly more of a problem than just the southeast tip of Montgomery County. We’re seeing impacts during hurricane storm surges. Uneven lowering of the ground surface changes flow patterns and potentially exacerbates flooding. I believe these issues warrant an investment in research and in infrastructure,” Houston said.

The SJRA General Manager noted that the Harris-Galveston Subsidence District is going to perform a “watershed study” up Spring Creek in south Montgomery County.

SJRA’s Cook said, “We need to plan for the future.”

“Reasonable minds could differ on whether subsidence has caused increased flooding in Montgomery County,” concluded Houston. “Clearly we have a water supply problem. In the water business, we have to look 50 to 100 years in the future.”

The following are some summary slides courtesy of Houston, Cook, and SJRA, on the subsidence and groundwater issues.

Source: SJRA.
Source: SJRA (with attributed data sources from Texas Water Development Board and Lone Star Groundwater Conservation District.)
Source: SJRA.
Source: SJRA (with attribution to USGS.)
Source: SJRA (with attribution to USGS.)
Source: SJRA (with attribution to USGS.)







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