Northpark Update: Ponds Get Deeper, Bridge Abutment Higher, Ditch Wider

4/15/2026 – In the quest the build the first all-weather evacuation route from Kingwood, there’s still much work to do. But contractors have made significant progress on Northpark in the last few weeks.

The two ponds that bracket Northpark Drive at the US59 entrance are getting deeper. Meanwhile, the bridge abutment east of the railroad tracks is getting higher. And Ditch One behind the businesses on the north side of Northpark is getting wider.

Also of note: concrete for the surface lanes that will flank the bridge is creeping ever closer to the UnionPacific Railroad tracks.

See details and photos below.

Entry Ponds Deepen

Contractors are deepening the two entry ponds at US59. Last week, it appeared that they had reached the designed depth in the north pond. Then came the rains. As you can see in the photo below, it had some significant erosion. And in this photo taken this morning, it appears contractors have returned to remove more silt.

North pond at Northpark and 59 on 4/15/26
Work on the south pond had paused this morning, while the focus returned to the north pond.

It appears that contractors made significant progress on the south pond. But you can clearly see the effects of erosion from the heavy rains.

To prevent similar erosion in the future, the ponds will be lined with concrete. That work should be completed by the end of next month.

Abutment Getting Higher

An abutment is a structure at the end of a bridge that absorbs lateral forces and moves traffic from ground level onto the clear-span portion of the bridge. Contractors are building the first of two abutments east of the railroad tracks in front of Public Storage and Dunkin’ Donuts. See below.

They started erecting walls last month. And now, they’re filling the area between them with layer after layer of stabilized sand and dirt.

Eastern abutment as of 4/15/26. Looking east.
Reverse angle shows how dirt between the walls is being layered in and compacted.
Side shot shows the work is already much taller than vehicles.

Drainage Ditch Widened

A drainage ditch (Ditch One) will take excess stormwater from Northpark and route it through a drainage ditch behind the businesses that line the north side of Northpark.

Ditch One has been widened and deepened back to its original dimensions. It had not been cleaned out for approximately 18 years!
Ditch One from ground level. Hydromulching will begin soon to protect the banks from erosion.

UPRR Crossing

Two surface turn lanes will flank each side of the bridge over the railroad tracks and Loop 494. Below, you can see the status of their completion.

Looking slightly E over the UPRR tracks.

On the north (l), pavement is complete up to the last two or three feet on each side of the tracks. On the south (r) pavement also stops short, but more work still needs to be done on the surface lanes themselves.

Keep in mind that after contractors complete paving, UPRR needs to install gates. And after that, a signal crew must make the temporary signals operational before the crossings become operational.

Loop 494

Loop 494 is virtually complete, but the Northpark intersection is not. This will be the focus of work in the near future.

Wider shot looking N along 494.
From opposite direction, you can see how wide Loop 494 will be where it approaches Northpark.

Other News

In coming days, crews will also:

  • Complete patches of sidewalks skipped due to utility conflicts on the project
  • Backfilling medians in preparation for final sod and seed
  • Install permanent traffic signals at Russell-Palmer Road and Northpark (expected completion by mid-April)

Please pack your patience, especially at the Russell-Palmer Intersection. Kings Mill residents use the intersection to make a U-turn.  The new traffic signals require significant underground work, a new traffic-signal control box, new signal poles, new conduit, new wiring and new programming. 

Caution

Please note: Work will continue in the center median of Northpark in preparation to put traffic in its final configuration. There are and will be many obstructions and potential hazards in this area, including construction workers and vehicles.

DO NOT cross into the work zone. Make turns only from delineated cross over areas. 

For More Information

Consult the Lake Houston Redevelopment Authority website Northpark Overpass Project page. This includes a 3-week look-ahead schedule, plans, simulated videos of the completed project, and more.

Posted by Bob Rehak on 4/15/26

3151 Days since Hurricane Harvey

San Jacinto Received Only 1% of HCFCD Spending in 2026 Q1

4/14/26 – The San Jacinto Watershed received only 1% of all HCFCD spending in Q1, despite being the county’s largest watershed and having the worst flooding.

Harris County Flood Control District (HCFCD) has published updated spending figures for 2018 Flood Bond Projects through the end of the first quarter of 2026. Analysis also revealed:

  • No Kingwood or Huffman Area projects have reached the construction stage yet
  • Spending on Lake Houston Area projects continues to lag other watersheds throughout the county.
  • HCFCD’s years-long spending slowdown may be stabilizing

Separately, Dr. Tina Petersen, PhD, HCFCD’s executive director, recently announced several positive developments for projects on Cypress Creek, the East Fork and Lake Houston Dam.

Let’s look at the funding analysis first. The screen captures below come from the HCFCD Activity Page and speak for themselves.

Overall Spending Slowdown Stabilizing

The chart below shows incremental spending for ALL watersheds since the start of the flood bond in 2018. But the far right shows only one quarter for this year so far. If the first quarter were annualized, it would approximately equal 2025 year-end spending.

Incremental spending after 2026 Q1 for all watersheds.

However, all phases of activity have declined dramatically since the management change at HCFCD in 2021.

Where the Money Went in Q1

The chart below shows the San Jacinto Watershed ranked 14th versus others. Of the $52 million total dollars spent, more than half of the watersheds received less than $1 million each. Only five watersheds received more than $2 million. The Cypress Creek Watershed received $22 million (36% of the total). That $22 million was three times more than the next largest watershed – White Oak at $6.76 million.

Q1 2026 spending for all watersheds totaled only $52 million.

Petersen attributes construction delays to “getting the funding in place.”

San Jacinto Spending Slowed, Too

Looking closer at the San Jacinto watershed, we can see it dropped sharply. But part of the apparent drop has to do with the fact that you are only looking at one quarter so far for the first quarter of 2026.

Incremental spending for the San Jacinto watershed since 2018

In Q1, HCFCD spent only $524,000 in the entire San Jacinto Watershed. Of that, $491,000 came from partners. Only $33,000 came from HCFCD’s bond or budget.

Breakdown of 2026 Q1 spending in San Jacinto Watershed. Dark blue represents partner spending.

But the most significant takeaway should be the volume of spending in the watershed compared to the total for all watersheds during the quarter…

$.052 million is exactly one one-hundredth of $52 million.

Q1 San Jacinto spending vs. total for all watersheds

And that’s for the county’s largest watershed – where the worst flooding occurred during Harvey. See below.

worst first
Chart showing feet above flood stage of 33 gages of misc. bayous in Harris County during Harvey.

Total and Construction Spending

Overall, HCFCD and its partners have spent almost $2.2 billion to date.

Total spending by watershed associated with the 2018 flood bond

But most of that has been on upfront studies, engineering and right-of-way acquisitions. Of the total $2.2 billion spent so far, only $1 billion has been on construction – 36%.

Construction spending through 2026 Q1 from 2018 flood bond.

Among watersheds, the San Jacinto ranks 13th on construction spending (not including County-Wide Spending) since 2018. White Oak ranks #1 with $148 million. To date, the San Jacinto watershed has received $21.5 million – one seventh of the construction dollars received by White Oak.

Status of Kingwood/Huffman Projects

Only three projects are active in the Lake Houston Area.

The Kingwood Diversion Ditch is still in engineering. It is fully funded and includes:

  • Additional channel capacity
  • A new diversion structure at the confluence with Bens Branch
  • Four bridge replacements
  • A new outfall to the San Jacinto West Fork south of Deer Ridge Park.

Petersen says construction could start as early as 2027.

She expects the Taylor Gully and the Woodridge Stormwater Detention Basin Project to start construction in May 2026. It is also fully funded and includes:

  • New stormwater detention basin
  • Bridge replacement at Rustling Elms
  • Channel widening and deepening

The Luce Bayou Watershed will receive a new detention basin near FM2100 and the Huffman-Cleveland Road to support regional drainage improvements. Construction plans for the fully funded project are nearing completion, according to Petersen.

Status of Lake Houston Gates and East Fork Detention

Farther upstream on Cypress Creek, Petersen said she expects to finally start construction on the TC Jester East Basin soon. HCFCD also claims to have finished construction on the Mercer Basin on Cypress Creek near the Hardy Tollroad.

When I met with Petersen and State Representative Charles Cunningham last week, she also addressed:

  • A $20 million Inter-Local Agreement with the City of Houston for new Lake Houston Gates. It is on the 4/16/26 Commissioners Court Agenda. See Item 126.
  • San Jacinto East Fork stormwater detention basins. It’s unlikely any will be built. But “we’ve identified several locations along the East Fork, where if someone wants to sell their property, we will buy it … and we will get FEMA funding to do that.”.

Posted by Bob Rehak on 4/14/26

3150 Days since Hurricane Harvey

How “Stacking Effect” Erodes Margins of Safety

4/13/26 – Since Hurricane Harvey in 2017, I’ve documented how numerous factors contribute to flooding. Individually, none is unique. You see them in operation everywhere around the world. But collectively, their impacts can “stack” in a way that degrades margins of safety and resilience – in some areas more than others.

San Jacinto West Fork at 59 during Harvey.
US59 Bridge over San Jacinto West Fork during Hurricane Harvey, where numerous flood factors converged.

Progressively Eroding Margins of Safety

Driving a vehicle makes a good analogy. A lonely highway. Rain-slick pavement. The dead of night. Bald tires. Too much speed. A tight curve. And a tired driver loses control.

In respect to flooding, the Lake Houston Area has:

  • Rapid upstream urbanization
  • Extensive floodplain development
  • Industrial-scale sand mining accelerating sedimentation
  • Low-gradient hydraulics
  • Constrained reservoir outflow
  • Fragmented governance

Now, Add 30-40% More Rain than Expected

A killer hurricane. Stalls over the Houston Area. The highest rainfall totals in the history of North America. Drainage channels clogged with sediment. A dam that can’t let water out fast enough. Homes built too close to water. Power gone. Communication out. Evacuation routes under water. And millions of people trying to flee. Simultaneously.

It’s not Hollywood; it’s Harvey.

Safety … Within Reason

We like to think of OUR safety as an “absolute.” Government and science will protect us, right? Wrong!

How much risk are we willing to live with? Said another way, “How much can we afford?” Engineers could design drainage systems that protect us from 100,000-year storms. But could we afford them? Probably not.

So, we look at probabilities and we compromise. We design systems to handle more than we expect. And they work great. Until the unexpected happens. Then we pray that everything doesn’t go wrong all at once. That our backup systems work.

And when they don’t, we’re left with that stale bag of potato chips in the back of the cupboard, rotting wallboard, and the kindness of strangers.

Systems Optimized for Competing Interests

We optimize communities to serve many different interests. Not just ours. And not just flood resilience. For instance, homes must be affordable, not just flood-safe. So, builders lobby for regulations that reduce their costs. And that may mean putting homes on smaller lots closer together, which…

  • Increases the percentage of impervious cover in a development
  • Speeds up runoff
  • Creates faster, higher flood peaks

And of course, to make new streets, you need sand for the concrete. So, fast-growing areas set up systems that let miners extract sand from floodways where it’s plentiful and pure.

But of course, that’s only a problem for people who live downstream. Until someone else does the same thing farther upstream.

Results: A Balancing Act

Here in the Lake Houston Area, we have a system where runoff is increasing, conveyance is decreasing, and control is fragmented—all at the same time. This combination is rare and particularly unstable.

But of course, it’s not all bad. Good people fight every day to keep you safe.

We have:

  • Harris County Flood Control District, widening and maintaining ditches, building stormwater detention basins, and maintaining thousands of miles of channels
  • Houston Mayor John Whitmire, Council Member Fred Flickinger, Houston Public Works Department and Coastal Water Authority, working to add more gates to the Lake Houston Dam
  • State Rep/ Charles Cunningham, who started a Lake Houston Area Dredging and Maintenance District to constantly remove accumulated sediment
  • State Rep. Dennis Paul, working to create a river-basin-wide flood control district
  • Thousands of first responders, honing rescue skills for the day they hope will never come
  • Armies of engineers, working to design drainage systems to keep you safe
  • Public servants like Harris County’s meteorologist Jeff Lindner, monitoring weather and maintaining flood warning systems 24/7/365 to warn you of severe weather
  • The Texas Water Development Board and its regional flood-planning groups
  • Representatives like Dan Crenshaw, who brought home hundreds of millions of dollars from Washington for flood-mitigation projects
  • Groups, like the Bayou Land Conservancy, Nature Conservancy and Coastal Prairie Conservancy working to preserve nature in ways that buffer us from flooding
  • Great people at FEMA, HUD, the GLO, and Texas Department of Emergency Management, ready to help when disaster strikes and all else fails.

It’s all a balancing act.

To prepare for the next flood, we must learn from the last – and act as if our lives depended on it.

Bob Rehak

For More Information

To learn more about how we can protect margins of safety, see the Lessons Page of this website.

Posted by Bob Rehak on 4/13/2026

3149 Days since Hurricane Harvey

Extreme Growth in Flatland With Constrained Drainage

4/12/26 – Numerous human and geologic factors drive flood risk. Where they exist in combination, flood risk degrades the most.

One of the most important “lessons learned” since Hurricane Harvey has been how A) extreme population growth in B) a flat river basin with C) a constrained outlet … combine to increase flood risk.

Extreme Population Growth in Region

Worldwide, urbanization and impervious cover (concrete, rooftops) represent the single most consistent, anthropogenic (man-made) driver of flooding worldwide. And…

Extreme population growth in the Houston region has fueled the growth of impervious cover.

According to U.S. Census Bureau figures released in January 2026, Texas ranked as the fastest growing state in the U.S. last year. And within Texas, Harris County grew more than any other county, adding an estimated 48,695 people – a 1% gain. Harris County’s population now tops 5 million people.

But the areas around Harris County are all growing rapidly, too – at least in percentage terms. Upstream from the Lake Houston Area:

  • Waller County grew by 5.7%
  • Liberty County grew by 4.4%
  • Montgomery County grew by 4%.

The U.S. grew only about 0.5% overall from 2024–2025. So these counties are outliers as is Texas itself. Since 2020, Texas has added more residents than any other state, with approximately 2.6 million new residents.

When you look closely at the numbers, there’s a clear bifurcation. Giant metro areas, such as Houston, lead in absolute population growth. But small, fast-developing fringe counties lead in percentage growth.

Why This Matters: Impervious cover

Waller, Liberty and Montgomery Counties lie right upstream from Harris County within the upstream San Jacinto River Basin. They rank among the fastest growing counties in the fastest growing state. That confirms rapid upstream urbanization in the watershed, which puts continued pressure on the San Jacinto West and East Forks.

Meanwhile, Harris County leads the nation in absolute growth. That means:

Just as concerning, to accommodate this growing population, we see floodplain encroachment throughout the watershed. For instance, right now, Scarborough and the Texas General Land Office are trying to develop more than 5,000 of the most flood-prone acres in southeast Texas near the confluence of Spring Creek and the San Jacinto West Fork.

Scarborough Area in center from FEMA’s Flood Hazard Layer Viewer based on pre-Atlas 14 data.

Land that once might have been dedicated to parks for flood control has become too valuable for that. Land owners want to catch the development gravy train.

Crossing at the Commons of Lake Houston Floodplains and General Plan
Proposed Signorelli Development “Crossing at the Commons of Lake Houston.” Dotted lines represent floodplains and floodway. Original residents were promised this would be land for recreation. Signorelli fought the City of Houston all the way to the Supreme Court of Texas for ten years for the right to build on this land.

Fragmented Governance Complicates Growth Factor

Fragmented governance also complicates the issue. Take, for instance, the Scarborough land that borders Harris County. If the land gets developed, Harris County would face increased flood risk while Montgomery County would reap benefits from expanding its tax base. So, the two counties have opposing interests.

Another example: Montgomery County gives tax breaks to sand mines along the San Jacinto that help fuel all this upstream growth. But sediment from those same mines washes downriver and gets deposited in the headwaters of Lake Houston. That sediment reduces conveyance and increases flood risk for the people in Harris County.

Infrastructure Bottlenecks and Peak Stacking

Drainage from all this extreme upstream growth feeds into a bottleneck with a constrained outlet – Lake Houston.

Drainage from the 2,500 square mile upper San Jacinto River Basin all flows through Lake Houston.

And extremely low gradients throughout this funnel means water moves slower and lingers longer. That increases the chances of peaks from different tributaries stacking on top of each other.

And finally, other bottlenecks exist, too. Like the FM 1960 Causeway and the Lake Houston Dam with its four small gates. They have a combined release capacity of just 10,000 cubic feet per second – one fifteenth the release capacity of Lake Conroe’s gates.

For More Information

See the Lessons Page of this web site. It condenses the major lessons learned from researching more than 3,000 posts since Harvey into a sort of quick guide.

Posted by Bob Rehak on 4/12/2026

3148 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

How A Terminal Reservoir with Limited Gate Capacity Increases Flood Risk

6/11/26 – Those seeking to understand flooding in the Lake Houston Area need to understand the placement and construction of the dam within the larger San Jacinto River Basin. Lake Houston is what hydrologists call a “terminal reservoir.”

Flood risk in the Lake Houston area is governed less by any single upstream factor and more by how all upstream factors converge at one critical place. And that critical place (the Lake Houston Dam) has extremely limited flood-gate capacity to lower the lake in advance of approaching storms.

gates for Lake Houston and Conroe
Lake Houston gates (l) can release 10,000 cubic feet per second (CFS). Lake Conroe gates (r) can release 150,000 CFS.

How All Risk Factors Converge in Terminal Reservoirs

As a terminal reservoir, Lake Houston backstops everything that happens anywhere upstream. A terminal reservoir is a reservoir located at (or very near) the downstream end of a watershed, such as the San Jacinto River Basin. It receives the cumulative inflows from all upstream tributaries before water exits to a larger receiving body, like a bay or Gulf of Mexico.

Lake Houston is the tip of a funnel draining more than 2,500 square miles from seven counties. That’s an area 50% larger than all of Harris County itself. See below.

Upstream watershed percent of Lake Houston Area
Percentages represent sub-watershed’s portion of acreage within Lake Houston’s drainage area which includes parts of seven counties. Lake Conroe controls only 13% of the drainage area.

Because of Lake Houston’s location, peak flows from multiple tributaries (East Fork, West Fork, Caney Creek, Peach Creek, Luce Bayou, Spring Creek, Cypress Creek, Lake Creek, etc.) can stack on top of each other.

During a storm, if peak flows from those tributaries arrive at different times, they may be manageable.

But if peaks arrive simultaneously, as they likely would in a large storm like Harvey, they create an exponential spike in water levels. And that can create catastrophic flooding in a terminal reservoir with limited gate capacity.

Six years ago, the SJRA’s River Basin Master Drainage Plan recommended 10 areas for additional upstream regional detention. But not one has even been bid.

Sediment Trap for the River Basin

Terminal reservoirs catch more than water. They also trap sediment from all uncontrolled upstream tributaries. Those include the mining corridors along the West Fork, East Fork and Caney Creek.

This leads to the progressive loss of storage volume behind the Lake Houston dam. That reduces flood-buffering capacity over time. It also increases reliance on dredging.

This is a much bigger issue in the Lake Houston Area than in Lake Conroe. Lake Houston traps sediment from an area seven times larger than Lake Conroe does.

Sediment from 87% of the river basin ultimately ends up in Lake Houston.

Computed from acreage figures supplied by San Jacinto River Authority

Plus, the largest sources of sediment are between the two lakes. Virtually all sand mines in the river basin are downstream from Lake Conroe and upstream from Lake Houston.

Low Gradient and Urbanization Increase Flood Risk

The low gradient in our flat coastal plain, also means that this terminal reservoir can back water up into tributaries, such as Bens Branch, where 12 people died at an assisted living facility for seniors during Harvey.

Urbanization compounds all these risks. Incremental upstream development in Montgomery, Waller and Liberty counties creates a cumulative increase in runoff volume and speed which amplifies peaks at the terminal location.

In other posts, I showed how even if each upstream development project meets the “no-net-runoff-increase” mandate locally, a system-level effect still concentrates peak flows at the terminal reservoir.

Peak flows in Lake Houston watershed during Hurricane Harvey. 400,000 CFS went over Lake Houston Dam.

The 400,000 CFS going over the Lake Houston Dam during Harvey created a wall of water 11 feet high. The volume was five times more than the volume of water going over Niagra Falls on an average day.

Implications

In summary, Lake Houston is the control point for a 2,500 square mile watershed. Lake Conroe controls only 13% of upstream drainage. Lake Houston controls 100%. The entire drainage area flows through this one control point with little help.

This heightens sensitivity to timing (when flood peaks arrive) and coordination (with Lake Conroe). Other than Lake Conroe, there is NO redundancy built into the system.

Sediment accumulation is not only inevitable, it is accelerated – by sand mining and rapid upstream development. This limits the buffering capacity of the lake for flood-control purposes. Sediment management is not optional. Safety requires it. Luckily, State Representative Charles Cunningham was able to start a Lake Houston Area Dredging and Maintenance District in the 2025 legislature.

The design of the Lake Houston dam also limits flexibility for flood management. Lake Houston has a 3,100-foot wide spillway but extremely limited gate capacity – 1/15th the capacity of Lake Conroe’s gates.

That limits pre-release capacity. It takes days in advance of a storm to lower Lake Houston enough to absorb anticipated incoming stormwater. But storms can veer away during that time. Yet millions of people depend on water from Lake Houston.

So dam managers must be extremely cautious about pre-releasing water. Before they open the gates, they must be sure the storm will replenish any water discharged.

Conclusion

Thus, gate capacity has outsized importance for flood safety. That’s why Houston Public Works and the Coastal Water Authority have studied the best way to add more gates to the dam ever since Harvey. But they haven’t yet finalized a design.

Meanwhile, people live with the flood risk of a terminal reservoir with limited gate capacity and little upstream help from other reservoirs.

For information about other factors that create flood risk, see the Lessons Page of this website.

Posted by Bob Rehak on 4/11/26

3147 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

How Sediment-Induced Loss of River Conveyance Increases Flood Risk

4/10/26 – Sediment buildups reduce river conveyance everywhere. But sedimentation is especially threatening in the Lake Houston Area because:

  • It creates hydraulic chokepoints that increase flood risk next to major commercial and population centers
  • Industrial-scale sand mining upstream accelerates erosion
  • The design of the Lake Houston Spillway doesn’t facilitate sediment discharge.
  • Lake Houston provides water for millions of people and loss of storage capacity is critical

Consequences of Sedimentation

This combination of factors is not unique, but it is unusual in its magnitude and consequences. Here’s why.

Lake Houston has a 3,160 foot long fixed height spillway for its primary discharge feature. While common in older water supply reservoirs, it provides few flood-control benefits. Studies to add tainter gates are not yet complete.

There is no way to remove sediment from Lake Houston except by dredging. Texas Water Development Board studies show that the lake has lost about 20% of its original storage capacity.

But the total storage loss is not the only issue; also consider where the loss is. Most sediment concentrates in the headwaters of the lake upstream from the FM1960 causeway where the river slows down as it meets a standing body of water.

Deceleration causes sediment to drop out of suspension. A delta has formed at this location, creating a hydraulic chokepoint that backs water up.

The Army Corps dredged approximately 2.1 million cubic yards from the area above FM1960.

Mouth bar was dredged and is now gone.
Looking S over West Fork mouth bar after Harvey and before dredging.

Subsequently, the City of Houston commissioned Callan Marine for a separate dredging effort to address additional buildups in Lake Houston’s headwaters.

East Fork Mouth Bar cost $18 million to dredge.
East Fork Mouth Bar after Imelda, but before dredging

We have seen what happens when we ignore sediment buildups. Thousands of people can lose homes and businesses in a major flood.

Need for Ongoing Sediment Removal and Preservation

The SJRA has studied sedimentation and sand traps for years to help control such buildups. But they have yet to implement any solutions.

Thankfully, a bill by State Representative Charles Cunningham created a Lake Houston Dredging and Maintenance District during the 2025 legislature. That should help manage sediment buildups in the future before they become critical.

But it’s no excuse to ignore things that contribute to excessive sedimentation. Those include failure to observe best management practices in mining and construction. They also include loss of riparian buffers and forests.

Confluence of Spring Creek and West Fork San Jacinto
5,300 flood-prone acres between the confluence of Spring Creek (l) and the San Jacinto West Fork (r) are slated for development by Scarborough, a Dallas-based developer and the Texas General Land Office. Note first of many upstream sand mines in upper right.

The area above borders 20-square miles of West Fork sand mines.

The loss of forests due to mining exposes more sediment to erosion during floods.

The loss of forests and riparian buffers leads to a triple whammy in terms of sedimentation. It increases the natural rate of erosion. It costs taxpayers hundreds of millions of dollars to remove it. And until they do, it increases flood risk.

As sand production on the West Fork winds down, now is the perfect time to discuss creating a Montgomery County Lake District or a new state park in this area. It could turn into a win/win for upstream and downstream interests.

For More Information

For more about the causes of flooding and how they can compound each other in the Lake Houston Area, see the Lessons Page.

Posted by Bob Rehak on 4/10/26

3146 Days since Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Role of Industrial-Scale Sand Mining in Lake Houston Area Flooding

4/9/2026 – Another “lesson learned” about flooding since Hurricane Harvey has been role of sedimentation from industrial-scale sand mining upstream from Lake Houston. It can only be appreciated from the air.

May 2024 flood at Hallett Mine on West Fork
May 2024 flood at Hallett Mine on San Jacinto West Fork near Northpark Drive in Kingwood. Note the difference in water quality in the ditch.

Few, if any, urban watersheds have such dense clusters of sand mines directly upstream from their water reservoirs in major river channels. This is one of the most distinctive features of flooding in the San Jacinto Watershed.

The mines not only contribute to flooding in an outsized way, they impair water quality, damage the environment and harm wildlife.

Chronic Sediment Mobilization During Floods

Most erosion happens during floods. And most sediment moves during floods.

More than 20 square miles of sand mines in the floodway and floodplains of the San Jacinto immediately upstream from Lake Houston provide a ready source of exposed sediment, ripe for mobilization.

I have photographed:

  • Sand mines pumping sediment over and through dikes
  • Dike failures.
  • Rivers capturing sand pits during floods
  • Mines dumping sediment directly into rivers

See a small sampling of photos below.

one of the prettiest places in texas
LMI sand mine on West Fork
breach out of sand pit
Breach of sand-mine dike into San Jacinto West Fork
Breach of Triple PG mine dike into Caney Creek in East Fork Watershed.
Hallett spill
Mine dumping sediment in West Fork
Hallett Mine
Same mine overflowing onto neighboring properties and then West Fork
New Sand Mining BMPs needed to control sediment pollution.
Pit capture at Hallett Mine. River now flows through mine instead of around it.
FM2090 is now threatened by the East Fork which has rerouted itself through an abandoned sand mine.
Pipelines carrying highly volatile liquids undercut by erosion from sand mine on West Fork.
East Fork Sand Mine undercutting more pipelines and leaking into Caney Creek
Abandoned sand mine equipment leaking oil into West Fork
abandoned dredge
Rusting dredge in abandoned sand mine in Humble on North Houston Avenue
white water caused by flaunting regulations
Confluence of Spring Creek and West Fork in August 2019. TCEQ cited Liberty Mines for discharging 56 million gallons of white sludge into the West Fork.
Sand freshly deposited during Harvey blocked West Fork 90%, according to Army Corps.
west fork mouth bar before dredging
Farther downriver, a mouth bar blocked the West Fork backing water up into thousands of homes and businesses. Army Corps has since dredged this.

The Houston area certainly isn’t the only place in the U.S. with alluvial floodplain mining. But rarely, if ever, do such practices take place with such impunity so close to the water supply for two million people.

For More Information

See the sand-mining page of this website for Best Practices in the U.S. and abroad; academic studies on sand mining; Texas sand mining laws/regulations; observations; and tax appraisal practices. An investigation found that virtually all of the sand mines shown above are in Montgomery County which taxed them as ag- and timberland rather than depleting assets.

Also search on the tag “sand mining” to find more than 300 posts containing thousands of pictures of mining practices in the San Jacinto River Basin.

Posted by Bob Rehak on 4/9/26

3145 Days since Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

How Subsidence Amplifies Flood Risk in Lake Houston Area

4/8/26 – Water extraction from aquifers, driven by population growth, causes subsidence. It is a well-recognized phenomenon across the U.S. and in southeast Texas. Here in the Lake Houston Area, differential subsidence is creating a bowl in the landscape that amplifies flood risk for people in southern Montgomery and northern Harris Counties.

Let’s look first at how, why and where subsidence happens. That understanding will help explain how it amplifies flood risk in the Lake Houston Area.

How Subsidence Happens

Extraction of groundwater – faster than nature recharges it – can cause silt and clay layers underground to compact. That compaction is permanent. Think of smashing a brownie; it will never regain its original shape. Innumerable tiny voids in the soil (or brownie) disappear, causing the surface above to sink.

For a more scientific explanation see the Harris Galveston Subsidence District FAQ on “What is Subsidence?”

Why Subsidence Happens

Population growth creates demand for the water in those aquifers, often at the fringes of major metropolitan areas. Developers build new subdivisions faster than water authorities can build pipelines to them from local surface water supplies, such as lakes.

Drilling wells is a much faster, more cost-effective solution at that stage of development – for both the water authorities and developers.

Plus, it’s not just the cost of the pipeline. You need to consider the cost of the water treatment plant. Both together can cost billions of dollars – far more than even a large subdivision could support.

Northeast Water Treatment Plant
Houston’s new Northeast Water Treatment Plant under construction in 2020. Projected cost was $1.7 billion.

Where Subsidence Happens

As a result, subsidence afflicts fast-growing regions across the U.S. Several examples include:

  • Atlantic Coast
    • NASA reports that that more than half of infrastructure in major cities such as New York, Baltimore, and Norfolk is built on land that sank, or subsided, by 1 to 2 millimeters per year between 2007 and 2020. Land in several counties in Delaware, Maryland, South Carolina, and Georgia sank at double or triple that rate. 
  • Chicago
    • 98% of the city reportedly sinks at 2 to 3 millimeters per year.
  • San Joaquin Valley
    • To feed the hungry growing population of the U.S., agricultural interests in the California’s San Joaquin Valley began over-pumping groundwater in the 1920s. According to the U.S. Geological Survey, the land surface there had subsided 30 feet by 1980.
  • Las Vegas
    • The city subsided 5 feet by 1980. But fast-growing Las Vegas extracts three times more groundwater than the natural recharge rate to this day. Subsidence in northern parts of the city forced residents to relocate.
  • Houston
    • During the last 100 years, Houston has consistently ranked among the fastest-growing major U.S. cities according the Census Bureau, frequently placing in the top five and even top two. Its subsidence problems are legendary. Parts of Baytown subsided more than 10 feet before the formation of the Harris-Galveston Subsidence District, causing the Brownwood subdivision to sink beneath Galveston Bay.

Differential Subsidence in the Lake Houston Area

But subsidence is not just a coastal issue. It also can threaten areas far inland. According to Mike Turco, general manager of the Harris-Galveston Subsidence District, areas in Spring has subsided by almost 4 feet and the area around spring has subsided by about 4 feet. Recent subsidence rates in Spring have generally been between 0.5 and 1.0 foot per decade. That’s much faster than at the Lake Houston Dam. So, in effect, we’re creating a bowl in the landscape.

And that bowl amplifies flood risk.

Even though homes may be 75-100 feet above sea level, they may only be one foot above the floodplain.

As water, from say Spring Creek or the San Jacinto West Fork, goes into that bowl, it increases erosion on the upstream side and deposition on the downstream side. That deposition contributes to pooling within the bowl. A double whammy.

So, when a major storm comes along homes may have had their “freeboard factor” wiped out. In engineering and insurance, “freeboard” means your “safety margin above the floodplain.” Live in a place long enough and you may find water creeping closer and closer to your home in successive storms.

Of course, subsidence is only one of many factors that could cause that. But it amplifies those other factors and increases your flood risk.

Past catching up with Montgomery County
Woodloch Subdivision damage near San Jacinto West Fork in Southern Montgomery County from May 2024 flood.

To complicate matters for the poor homeowners shown in the picture above, Dallas-based Scarborough recently purchased 5,300 acres nearby between Spring Creek and the West Fork. Any new subdivisions built on that property would use well-water and further contribute to subsidence.

For More Information

Your safety ultimately depends on maintaining a healthy safety margin – much like the distance between you and the car in front of you on the freeway. We’ve all seen what can happen without enough distance.

For a discussion of other factors that contribute to flood risk, see the Lessons page of this website.

For more on subsidence and flooding, see:

Posted by Bob Rehak on 4/8/26

3144 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

How Flat Terrain In Southeast Texas Increases Flood Risk

Flat terrain is one of the most under-appreciated aspects of flood risk. It complicates virtually every aspect of flood control.

Flat terrain increases flood risk primarily by reducing the speed of runoff. It causes water to pool rather than drain away. Also, lack of gradient lets floodwaters spread wider, increases sedimentation, backs water up into storm sewers, and creates unpredictable backwater effects.

Spreading Wider

In steep, mountainous areas, a one-foot rise in a river can be relatively contained; it won’t spread out much. But in flat areas, water spreads out easily. Even a slight rise in water level can submerge numerous properties. And that water may not drain away quickly. As water fills channels, it backs up water into storm sewers and may cause street flooding.

Increases in rainfall can also shift floodplain boundaries significantly, as we saw recently with the introduction of new draft flood maps based on Atlas 14. Homes once considered outside of floodplains are now within them.

Increasing Sedimentation

Flat terrain also makes rivers move slowly. This enables suspended sediment to settle and reduces a river’s capacity to convey stormwater, leading to more frequent flooding.

It can also lead to the creation of sand bars, especially where rivers meet standing bodies of water, such as Lake Houston. During Harvey, we saw “mouth bars” grow thousands of feet on the East and West Forks above Lake Houston.

west fork mouth bar
San Jacinto West Fork Mouth Bar after Hurricane Harvey

Mouth bars are sand bars found at the mouths of rivers. Such blockages create partial sediment dams that back water up and promote even more deposition upstream. For instance, see below.

Farther upstream from the West Fork mouth bar, additional freshly deposited sand during Harvey reduced West Fork conveyance by 90% at this location, according to the Army Corps.

The Army Corps has since dredged the West Fork. However, while dredging can temporarily deepen a channel, it does nothing to increase the slope (gradient). Without a steeper slope, the river remains slow, and new sediment quickly refills the dredged areas.

That is why the Army Corps recommended a maintenance dredging program and why State Rep. Charles Cunningham’s Lake Houston Dredging District is so important.

Unpredictable “Stacking” Effects

In steep river systems, flood waves pass quickly. But in Southeast Texas, flood waves move slowly down rivers. Peaks linger and lengthen. This increases the probability that the peaks will synchronize, i.e., stack on top of each other.

That’s especially true in large storms, such as hurricanes, that may stall over an area for days and dump rain uniformly across the region. Stormwater peaks from different tributaries then stack on top of each other as they moves downstream.

New Sand Mining BMPs needed to offset sediment pollution.
The highest flooding in Harris County during Harvey occurred at the confluence of Spring Creek (L) and West Fork (R). Looking NW from over I-69 Bridge.

Other Backwater Effects

The low gradient of streams in southeast Texas makes them extremely sensitive to a variety of backwater effects.

In flat river basins like the San Jacinto, Trinity and Brazos, mild slopes amplify “backwater effects.” Examples include

  • Tributary confluences:
  • Reservoir backwater:
    • Lake Houston backs up the lower San Jacinto West and East Forks plus a number of creeks and bayous for miles upstream.
    • As peaks arriving from different streams arrive, they stack on top of each other.
    • During floods, even modest lake-level rises can push water far upstream into Montgomery County
  • Tidal influence:
    • Near-coast systems can experience tidal backwater
    • Storm surge from the Gulf can reach miles inland, blocking inland rainfall from draining to the Gulf.
  • Infrastructure bottlenecks:
    • Bridges, culverts, sand bars, levees, dikes, and new developments
    • Can constrict conveyance and back water up
Illegal fill
Same confluence as shown above but from a different angle shows how floodplain fill is constricting floodplain storage and the floodway near a critical choke point, the I-69 Bridge

Implications for Policy Making

In low gradient systems, many streams become hydraulically coupled during floods. So, basin-wide coordination is essential.

That’s why the SJRA’s Joint Reservoir Operations Study is so crucial and why fragmented governance increases flood risk. We need river-basin-wide flood control.

We must also be more sensitive to:

west fork sand mine
West Fork sand mine frequently inundated by floods illustrates need for vegetative controls to reduce erosion.

Summary

To summarize, in flat coastal plains with low-gradients:

  • Low slope = low velocity = poor drainage
  • Water spreads laterally instead of moving quickly downstream, flooding many structures
  • Stormwater from different tributaries has a higher chance of stacking up
  • Sediment accumulates faster
  • Infrastructure bottlenecks can have large spatial impacts.

Posted by Bob Rehak on 4/7/26

3143 Days since Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

Reservoir Coordination Still Elusive After 53 Years

4/6/26 – One of the biggest “lessons learned” from Harvey is that coordinated Joint Reservoir Operations are crucial. The San Jacinto River Basin has two reservoirs controlled by dams. But coordinating their operation to reduce flooding remains elusive after 53 years.

The San Jacinto River Authority (SJRA) finished the Lake Conroe dam in 1973, but is still seeking public input on its Joint Reservoir Operations Study. They hope to have a first draft of the study by the end of 2026.

Benefits of Reservoir Coordination

Other authorities around the world have long recognized the benefits of coordinating the operations of multiple dams on their rivers. Benefits include:

  • Enhanced flood control and mitigation – By acting in tandem, dams can reduce flood peaks more efficiently than isolated dams.
  • Improved water security and drought resilience – Coordinated dam systems can manage water storage across a basin to alleviate water stress during dry seasons.
  • Reduced sediment transport –  Tandem operation can reduce peak flows that cause heavy erosion, clogging rivers and downstream lakes.
  • Increased hydropower generation – Although not a factor in the San Jacinto Basin, coordinated operations allow water to be used multiple times as it passes through a series of dams, exponentially increasing total energy output from the same water resource.
  • Environmental sustainability – Strategic releases of water can sustain downstream ecosystems, habitats, and species, as seen in the U.S. Sustainable Rivers Program.
  • Improved navigation and trade – A system of coordinated locks and dams can regulate river flow consistently, facilitating the transport of goods via barges and promoting regional economic development.
  • Water security – Upstream dams can supplement the water supply in downstream dams that may support major metropolitan areas. Lake Conroe, for instance, provides backup to the smaller Lake Houston, which is the primary water supply for more than 2 million people.

River Authorities that Manage Multiple Dams for Flood Control

Examples of coordinated management abound. Take for instance:

  • In Texas, the Lower Colorado River Authority (LCRA) provides a textbook example of coordinated dam management for flood control through the Highland Lakes system. The LCRA manages a “staircase” of six dams northwest of Austin. All six assist with flood mitigation. They operate as an integrated unit to protect downstream communities.
  • Tennessee Valley Authority manages a network of 9 main-river dams and 22 tributary dams. The system is designed to catch heavy runoff in tributary reservoirs before it reaches the main river, significantly reducing flood risks for downstream cities like Chattanooga. The TVA operates these dams as a single unit. That way, they also ensure a consistent water depth of at least 11 feet along the entire 652-mile main channel. That lets 28,000 barges transport goods annually.
  • The Columbia River System (CRS) consists of 14 federal dam projects managed as a coordinated system for power, flood control, and fish protection.
  • California Department of Water Resources found that “weather-informed reservoir operations” at Lake Oroville and New Bullards Bar Reservoir can further reduce flood risk for communities along the Yuba and Feather rivers during extreme atmospheric river storm events and potentially benefit water supply during drier periods.
  • In the Delaware River Basin, a “flexible flow management program” mitigates flooding impacts immediately downstream of reservoirs.

Two Key Houston-Area Reservoirs Have Different Missions, Management

So, why can’t the SJRA manage two dams?

For one thing, SJRA only controls Lake Conroe. The Coastal Water Authority controls Lake Houston.

For another, the two dams have slightly different goals and radically different construction.

  • Lake Conroe was conceived as a water supply and flood control reservoir (even though SJRA now claims Lake Conroe is strictly for water supply). Lake Conroe’s tainter gates can release 150,000 CFS.
  • Lake Houston, on the other hand, is primarily for water supply. It has limited flood control capability because of its fixed height spillway. Lake Houston has only four small gates with a combined release capacity of 10,000 cubic feet per second (CFS).

Engineers are currently studying ways to add more and bigger tainter gates to Lake Houston. The current plan under study would boost the release rate to 78,000 CFS, thus matching the highest release rate ever from Lake Conroe (during Harvey). That would enable better coordination between the dams.

Why It Matters

Timing of releases can materially affect downstream flooding in a densely developed floodplain. During Harvey, a wall of water 11 feet high was going over the Lake Houston spillway. 16,000 homes and 3300 businesses behind the dam flooded. It backed water up for miles. Lake Houston’s Dam had 5X more water going over it than Niagra Falls usually does – enough to fill NRG Stadium in 3.5 minutes – 425,000 CFS.

Lake Houston Dam During Harvey. Can you even see the gates at the right end of the spillway?

Twenty percent of all homes and forty percent of all businesses in the area were affected.

Lake Houston Area Flood Task Force

Getting the water out faster is crucial. But it must be done safely. In a way that doesn’t hurt downstream interests.

While Coastal Water Authority figures out how to add more gates, SJRA is building a forecasting tool for the entire watershed that has the potential to:

  • Improve coordination between the dams
  • Inform decisions about pre-releases and gate operations
  • Enhance emergency management

For More Information

See SJRA’s presentation at the Humble Civic Center on 3/5/26 for more on Joint Reservoir Operations.

See ReduceFlooding’s new Lessons page for more “lessons learned” about flooding. It’s my attempt to distill my most important findings from more than 3000 posts since Harvey.

Posted by Bob Rehak on 4/6/26

3142 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.