Subsidence, Flooding and the Lone Star Ground Water Conservation District Election
Note: If you are from Harris County, you cannot vote in this election, but it still affects you. Please forward this link to friends in Montgomery County. This is an update of a previous post and recommends some candidates at the end.
Next Tuesday, Montgomery County voters will elect board members to the Lone Star Groundwater Conservation District (LSGCD) for the first time ever. Some candidates advocate using more groundwater, a move that could give residents cheaper water in the short run, but which could also cause subsidence and contribute to flooding in the long run. It could even create shortages, raise water costs and limit growth. Here’s how.
How Subsidence Can Increase Flood Risk
When ground subsides, it sinks. In this region, the primary cause is groundwater removal.
“Using surface water instead of groundwater reduces subsidence. Where groundwater use has been reduced, subsidence has generally ceased,” said Michael Turco, General Manager of the Harris-Galveston Subsidence District. 
Southern Montgomery County, and northern and northwestern Harris County have some of the highest subsidence rates in the region today.
Yet some Montgomery County voters advocate removing more ground water because, at this moment, it’s cheaper than surface water. They are betting their future and their neighbors’ futures on it.
One part of Baytown, the Brownwood subdivision, is a classic, visually striking, and cautionary example of subsidence. Brownwood subsided so much that it became uninhabitable. Excessive groundwater pumping by industry around Galveston Bay caused the area to sink ten feet.
In 1944, the area that would become Brownwood in Baytown was starting to show signs of development.
By 1978, Brownwood was well developed…and sinking fast. Then, in 1983, a 12-foot storm surge from Alicia destroyed the entire community.
Today, Brownwood floods so much that all homes are gone. Baytown converted what was left into a park.
Coastal vs. Differential Subsidence
Inland areas also face flood threats from subsidence, but not the kind associated with storm surge. In Montgomery County and surrounding areas, the flood threat comes from sinking at different rates in different places.
Example: subsidence around Jersey Village created a “bowl” within the landscape that has been linked to increased flooding there. See the contour map below.
Other examples: The Woodlands and Kingwood sank two feet in the last century. Most of Buffalo Bayou sank eight.
Red contours show subsidence in last century. Blue contours show subsidence in first 16 years of this century. Note how the small red circle near Jersey Village (A) quickly expanded to the large blue circle around it. Also note (B) the widening gap between red and blue at the top of the frame. This shows that areas that depend on groundwater, i.e., Montgomery County, are subsiding faster than those on surface water, i.e., most of Harris County. Source: Harris-Galveston Subsidence District.
Three Ways Unequal Subsidence Increases Flood Risk
Unequal sinking contributes to flooding by changing the slope of rivers and streams.
- If the slope increases, water flows faster and contributes to flooding downstream.
- If slope decreases, water moves more slowly or even pools, contributing to flooding upstream.
- Sinking between two drainage basins can even divert floodwater from one basin to another.
The “Pump-Now, Let-Somebody-Else-Pay-Later” Mentality
Subsidence happens so slowly that some people claim it’s not a problem – especially those on higher ground. They want to continue pumping water from wells because they perceive it to be cheaper than surface water.
It can be – at least in the short run– until wells run low or dry. Then pumping costs increase – often along with salinity – and the people who depend on the well are out of water and out of luck.
Much of the groundwater in Montgomery County used for human consumption is pumped from the Jasper aquifer which also affects Harris and Galveston Counties. Source Harris-Galveston Subsidence District.
And that high ground they enjoyed? If it subsides faster than surrounding areas, they can alter the slope of rivers and creeks, increasing their own flood risk, like Jersey Village. This is currently happening in southern Montgomery County and northern Harris County.
Depleting at More Than 500X the Recharge Rate
Still, some people say, “I’ll worry about that when it becomes a problem.”
Problem is:
- We’re depleting aquifers much faster than they’re recharging.
- At the current rate of pumping and population growth, modeling shows that the Jasper aquifer will drop 224 feet by 2070.
- USGS estimates that the Jasper recharges, on average, at only one-tenth of an inch per year.
- That means it could take 26,880 years (10 x 12 x 224) to replace the Jasper groundwater that residents will use in just 50 years.
The rate of depletion will exceed the rate of recharge by more than 500X – an environmental catastrophe.
More Expensive in Long Run
Now consider this. Experience and science show that pressure in an aquifer will decrease when pumping exceeds the recharge rate. And as pressure in an aquifer decreases, the cost of bringing water to the surface increases dramatically. Then recovery is no longer economical, i.e., competitive with surface water. It’s like the oil industry. As a rule of thumb, half the oil in reservoirs is left underground. It’s simply too expensive to recover because of low pressure.
For all these reasons, most counties in the region are trying to switch people to surface water. Groundwater withdrawals in Waller, Liberty, Grimes, Walker and San Jacinto Counties have either declined or stayed the same since 2000.
Counties surrounding Montgomery have either decreased groundwater pumping or kept it steady.
Meanwhile, Montgomery County’s groundwater withdrawals have soared. A report by LBG Guyton Associates to the Lone Star Groundwater Conservation District showed that the largest pumping increase since 2000 occurred in Montgomery County.
Montgomery County groundwater pumping virtually tripled in the last three decades.
Montgomery County Growth
The surge in Montgomery County groundwater usage is largely because of growth. On a percentage basis, Montgomery County is growing faster than any county in the region except Fort Bend.
Montgomery County growth trails only Fort Bend.
So Why Worry NOW?
Water resources take so long to develop that they need to be planned 50 years ahead. If Montgomery County hopes to keep growing rapidly, where will water come from to support that growth? Especially if voters undermine financial viability of the half-billion-dollar, surface-water treatment plant – that they just built – by shifting back to groundwater!
The San Jacinto River Authority (SJRA) finished the plant in 2015 to comply with the LSGCD requirement to reduce groundwater use. Many people don’t realize that the SJRA pumps groundwater from 38 wells to supply The Woodlands. The SJRA must comply with LSGCD regulations like everyone else.
To comply, the SJRA and 90 other water utilities who partnered with them, drew up plans for a surface water treatment plant and signed contracts to purchase water from it. The SJRA then borrowed money from the State and built the plant. Inevitably, the cost of water increased to cover construction.
After it was built, several providers changed their minds and began pushing the LSGCD board to produce more groundwater to take costs back down. When the board refused, the breakaway faction succeeded in getting a measure on November’s ballot to elect an LSGCD board more favorable to groundwater pumping.
Since 2001, the LSGCD has had a nine-member board appointed by a combination of local entities. They include Montgomery County, cities, and MUDs. The SJRA even has one seat. The appointees are experts who fully understand the future consequences of subsidence and unlimited groundwater pumping; an elected board may not.
If an elected board ignores the science and allows unlimited groundwater pumping, it would affect the financial projections on which the surface water plant was built.
Betting the Future
If people vote for candidates who advocate using “cheaper” groundwater in the short term, they will also be voting for subsidence and policies that limit long-term growth. Without question, they will be betting their future, their children’s futures and their neighbors’ futures on a rapidly depleting water source.
If that’s the will of the people, so be it. I just hope they don’t set a precedent that residents in neighboring counties follow. If so, we could all be sunk.
Candidates Who Believe in Science-Based, Groundwater Management
Fortunately, there are people running for LSGWCD board positions who believe in science-based, groundwater management. Knowledgeable acquaintances in Montgomery County recommend the following candidates who, they say, have professional experience related to water management and/or water supply, and would work to preserve Montgomery County’s future, reduce subsidence and prevent flooding:
- Place 1, County Precinct 1 – Stuart Taylor
- Place 2, County Precinct 2 – Garry Oakley
- Place 3, County Precinct 3 – Rick Moffatt
- Place 4, County Precinct 4 – Gail Carney
- Place 5, County At Large – Gregg Hope
- Place 6, Conroe – Jackie Chance, Sr.
- Place 7, The Woodlands – Kent Maggert
Please spread the word to every voter you know in Montgomery County.
Posted by Bob Rehak, November 3, 2018
431 Days since Hurricane Harvey
