Tag Archive for: Lake Conroe

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.

Limitations of Multiple Small Detention Basins at Watershed Scale

4/5/26 – Today’s “lesson learned” from almost nine years of research into flooding is about the counterintuitive “Limitations of Multiple Small Detention Basins at Watershed Scale.”

Research shows that hundreds of small ponds built during subdivision construction do little to reduce flooding at the watershed scale and may increase it in places. A 2009 National Academies study found (Page 422) that “In many cases the site-by-site approach has exacerbated downstream flooding and channel erosion problems as a watershed is gradually built out.”

Regional stormwater detention basins are superior to multiple small, on-site basins because they offer better flood control, higher water-quality treatment, and increased cost efficiency.

Regional basins effectively manage large-scale runoff from multiple developments by providing comprehensive peak flow reduction. Simultaneously, they reduce the maintenance burdens and land-use inefficiencies of scattered, small, and often poorly maintained small ponds.

With the exception of Lake Conroe, the 2,500 square miles upstream from the Lake Houston Area in the upper San Jacinto River Basin has no other regional detention basins/reservoirs as of this writing. And Lake Conroe controls only 13% of the watershed flowing into Lake Houston.

How Detention Basins Work

The goal of detention basins in general is to ensure post-development runoff is less than or equal to pre-development rates. That’s important because increases in impervious cover during development increase the speed of runoff. So floods peak faster and higher.

Detention basins do nothing to reduce the total amount of runoff. They just spread it out over a longer time. And that spread increases the probability that peak flow from one tributary will stack on top of another peak somewhere downstream in the river systems branching structure.

Peak Stacking

While detention basins effectively reduce peak flows at individual sites, they don’t necessarily reduce peak flows everywhere because of this stacking effect.

A flood-frequency analysis of large European river basins found that “If a flood peak in the main river is superimposed by a simultaneous peak from a tributary, the magnitude of the flood peak may be increased significantly downstream.”

This graph illustrates the concept.

What happens downstream when peaks from different tributaries arrive simultaneously instead of separately.

The simultaneous arrival of peak flows from different tributaries can increase the height of a flood even if total volume remains unchanged.

Factors that Contribute to Peak Stacking in Lake Houston Area

Several factors present in the Lake Houston Area increase the probability of this “peak stacking.” They include:

  • Convergence of many major tributaries and sub-tributaries
  • Low gradients, flat terrain
  • Rapid upstream growth
  • Largely uncontrolled sedimentation reducing conveyance and creating backwater

Detention basins usually have no way to delay or accelerate the timing of releases. Stream levels control timing; when they get low enough, water can start trickling out of the basin. But that’s precisely what maintains peaks longer. And that longer peak increases the probability of peaks merging at confluences instead of arriving at different times.

Regional Detention Prospects Look Bleak for Lake Houston Area

While regional detention may be preferable and more effective than hundreds or even thousands of small detention basins, it is difficult to find space for regional basins – at least with a Benefit Cost Ratio (BCR) that justifies the project.

A recent feasibility study on regional detention upstream on Spring Creek offered little hope after developers snapped up the land before the study was completed. The federal government also excluded social benefits from BCR calculations during the study.

The same land could have been purchased decades ago for a fraction of the cost when it was good for nothing but timber. But the BCR would have been even lower because few people lived in the “benefit” area at that time. Damage to structures would have been minimal.

The San Jacinto River Authority Master River Basin Plan recommended ten similar detention projects in 2020. But six years later, not one is funded.

Ten of 16 projects recommended by SJRA’s Master River Basin Drainage Plan involved regional detention basins.

Similarly, HCFCD’s promising Little Cypress Creek Frontier Program, which would have created regional detention, has been cancelled. Harris County Commissioners reportedly felt reluctant to spend money where few people lived.

These examples highlight a systemic problem: Most effective regional detention basin projects with available land are far upstream in their respective watersheds where few people live. That means the people who benefit from them may live across jurisdictional boundaries, such as city or county lines.

For instance, the Spring Creek detention basins were in Waller County. But most of those who benefited from them lived in Montgomery County. That makes financing and managing them more difficult.

Conclusion

Regional detention basins are more efficient and effective than small local detention basins. But until people of the river basin recognize the benefits of working together on flood mitigation, we must live with distributed detention and suffer the consequences.

Posted by Bob Rehak on 4/5/2026

3141 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.

Reminder: SJRA Joint-Reservoir-Operations Meeting in Humble

3/4/26 – The San Jacinto River Authority (SJRA) will hold a meeting at the Humble Civic Center to solicit public input on its Joint-Reservoir-Operations Study. Please come:

  • March 5 @ 6:00 pm – 8:00 pm
  • 8233 Will Clayton Pkwy, Humble, TX 77338

Representatives from the SJRA, Coastal Water Authority, City of Houston, Humble, and the study consultant, Black & Veatch Engineering, will explain the study and field your questions. The meeting will feature informational tables where residents can talk with engineers one on one, plus a presentation.

According to Matt Barrett, PE, SJRA’s Water Resources and Flood Management Division Manager, “one of the main objectives of the study is to determine if there are any benefits to pre-releases from Lake Conroe and Lake Houston.”

Not an Easy Question

While that may seem obvious to flood victims, the question can get complicated. In involves an almost infinite number of weather scenarios, engineering variables and water-supply considerations. For instance:

  • How much rain will fall and how fast? Which direction will the storm come from? Where will the most rain fall in the river basin?
  • How many gates can the budget support? Will they be able to keep up with Lake Conroe’s discharges?
  • What happens if a storm veers away at the last minute? How can we make sure pre-releases don’t waste water or flood downstream neighbors?

In my mind, the question is not “if” pre-releases have a benefit, but “when.”

And that relates to a second objective of the study: to develop a flow forecasting tool for the entire river basin.

Accordingly, said Barrett, “The study will also consider the travel time of water between Lake Conroe and Lake Houston, a factor that’s crucial in evaluation of pre-releases.”

Experience of Other River Basins

Coordinating pre-releases from multiple dams is not an unusual problem. Most rivers have more than one. For instance, multiple dams on the lower Colorado River help keep Austin from flooding.

There’s a well-established body of work showing that coordinating operations across multiple reservoirs can produce measurable flood-mitigation benefits. However, hydrology, travel times, and downstream constraints must align. 

The big win is usually shaving peak flows. Engineers in other watersheds have seen flood-mitigation benefits when their studies identified operating rules that:

  • Prevented “release stacking” – We must avoid upstream releases arriving at the same time as peak local inflows from other uncontrolled tributaries, such as the East Fork or Spring and Cypress Creeks
  • Used forecasts intelligently – Pre-release only works when forecast confidence and downstream capacity justify it
  • Respected downstream constraints – Don’t exceed channel limits. 

Make-or-break technical questions for the San Jacinto Watershed will likely include:

  • Travel time for water between Lake Conroe and Lake Houston and how that changes with different base flows.
  • Downstream constraints such as local rainfall in the Lake Houston watershed
  • Forecast confidence and decision triggers – When will forecasts be reliable enough to justify pre-release without wasting water supply or making flooding worse.
  • What will the study optimize for? Peak flood stage at specific gages? Total damages? Avoiding emergency spillway use? Protecting evacuation routes? Something else?

Bring your questions to the Civic Center.

Why is This Study Taking So Long?

The project was delayed by a change in plans in adding gates to the Lake Houston Dam. SJRA first applied for a grant to study synchronizing releases from the two dams back in 2020. However, after crest gates to the spillway portion of the dam proved infeasible, the City of Houston decided to study adding tainter gates to the earthen eastern portion of the dam.

site of proposed gates for Lake Houston on east side of dam
Tainter gates like Lake Conroe’s will now go in the earthen portion of the dam above, not the concrete spillway in distance.

That new study is now 30% complete. That’s far enough along to start making engineering decisions. But to complicate things even further, costs have escalated because of inflation. That raises some additional questions…and scenarios. How many gates can the City afford? Will they be able to keep up with releases from Lake Conroe? And will Black & Veatch even examine scenarios involving additional gates?

If history is any indication, you can bet that members from the Lake Conroe Association will be there to talk against pre-release. If you want your interests represented in this study, make sure you come tomorrow night. And make sure they include the scenarios in their study that represent your biggest concerns.

Posted by Bob Rehak on 3/4/26

3109 Days since Hurricane Harvey

How SJRA Set Lake Conroe Release Rates During May Storm

5/24/24 – The SJRA board reviewed a presentation yesterday about Lake Conroe release rates during the early May storm this year. Sadly, while some people flooded, far fewer flooded than in Harvey, despite the fact that the peak inflow to Lake Conroe was higher during this storm than it was in Harvey.

Better management of the temporary floodwater storage space between Lake Conroe’s normal lake level and flowage easement may have made the difference. But there may be opportunities to make an even bigger difference.

Dissecting a Disaster

In early May this year, the headwaters of Lake Conroe received half a year’s rainfall in a few days. It was extreme to say the least. At the peak of the inflow, dam operators were releasing almost 72,000 cubic feet per second, yet the lake level still rose.

That was the second highest release rate in the history of the San Jacinto River Authority (SJRA). Only during Hurricane Harvey did the SJRA release more – 79,000 CFS at the peak.

The peak inflow was greater during this event than during Hurricane Harvey, according to Bret Raley, the San Jacinto River Authority’s Lake Conroe Division Manager.

This time, hundreds of homes flooded downstream. Thousands more were threatened. But it wasn’t nearly the disaster that Harvey was.

Regardless people who flooded or nearly flooded want to know why the release rate was so high and whether it could have been lower. Raley’s after-action report to the SJRA board meeting yesterday provides some answers.

Presentation to SJRA Board on May 23, 2024

Here’s a link to Raley’s entire presentation to the SJRA Board.

You can watch it starting at 37 minutes and 40 seconds into this video. It lasts 15 minutes.

Or you can review the slides below and my summary.

Note: some slides in this presentation use slightly different time periods.

Temporary Storage Provides Partial Buffer Against Flooding

Raley began with a recitation of SJRA’s top priorities re: operation of the Lake Conroe Dam.

He stated that “Our number one priority is … to preserve and protect the structural integrity of the dam. If we did not, the ramifications would be unimaginable.”

“I contend we are protecting public safety. How? Through a vigorous inspection and maintenance program; post-event assessments; and safe spillway operations.”

The dam, he says, provides a buffer against the full brunt of floodwaters. You’ll see later in the presentation, that at times, the inflow exceeded the outflow. Even though the Lake Conroe dam wasn’t designed for flood control, it still provides a modest buffer of temporary storage that helped reduce downstream impacts.

Only 15% of Upper Basin Protected by Dam

The Lake Conroe dam controls only about 15% of the square mileage in the upper San Jacinto River Basin.

The upper San Jacinto River basin includes nine different watersheds that all drain to Lake Houston. Said Raley, “Ours is at the very, very top of what I sometimes refer to as a funnel. Tthe bottom of the funnel is Lake Houston, the Lake Conroe watershed is at the top.”

Raley continued, “The Lake Conroe watershed is only 450 square miles. But it’s also the only watershed in the entire 3000 square miles controlled by a gated structure. The other nine watersheds flow through seven different counties.”

When rain makes its way to Lake Houston depends on when and where the rain fell. In this event, the heaviest rain fell in the West Fork (Lake Conroe) and East Fork watersheds. It could have been much worse if heavy rains had also fallen in Lake, Spring, and Cypress Creek watersheds.

Permit Limits Storage Higher Than 201 Feet Above Sea Level

The Lake Conroe Dam’s operating permit imposes several limitations that operators must contend with.

Said Raley. “The dam was constructed pursuant to a permit from the State of Texas. It authorizes us to store up to an elevation of 201 feet above mean sea level permanently. We also have the authorization to store above 201 temporarily during storm flows.”

“The permit also requires us to pass the inflows once the lake level gets above 201. But any water released below 201 must be used against permitted water rights. So there must be a permittee with available water, and then that permittee can ask to use the water.”

“The City of Houston may have, from time to time, water that’s available, and if so, they can call on it.”

Storage, Mitigation and Pre-Release

Raley then discussed the three main things he wanted people to remember from his presentation. He summarizes them in this slide.

Raley says that water which rises above 201 feet above mean sea level (MSL) cannot be held back; the lake’s operation procedures mitigate peak downstream flows; and that if the City of Houston wants to lower Lake Conroe, the City must ask for the water out of the two thirds of the lake that it owns.

Raley never addressed why the SJRA discontinued its seasonal lowering program that was in effect for several years after Harvey. The existence of that program contradicted some of the points he made in his presentation. That leads one to wonder how firm the rules he describes really are in emergencies.

Water Must Be Released as it Starts to Rise

After introducing his key points, Raley goes into more detail on each.

Raley discussed the differences between water-supply and flood-control reservoirs. “Lake Conroe is a water supply reservoir,” he said. “The intent is to keep the reservoir as full as possible to maintain your supply. In a flood control reservoir, you want to maintain capacity. You want to maintain space that can accept inflows so that you can absorb that water before having to pass it.”

Normally, Only 18″ Between Top of Water and Top of Gates

The design of the tainter gaits on Lake Conroe is another constraint. They do not allow much room for water to rise.

The photo on the left shows a gate in the normal resting position with the lake at the normal level. Water can rise only 18 inches before overtopping the gate.

If that happens, operators lose control. So, as the water rises, they must elevate the gate to stay ahead of rising levels. Remember, storms often pack high winds that create waves. Water can be choppy, not placid as shown here.

“Our gates are not designed to be overtopped” said Raley. “So, we must raise them incrementally to maintain safe freeboard.” Freeboard is an engineering term that, in this context, means “safety margin.”

The second photo shows the downstream side of a gate. Sheet flow coming over the top could destroy this support structure says Raley. “They’re just not designed to withstand that kind of force.”

Six Feet of Buffer Space

A flowage easement lets the SJRA flood properties surrounding Lake Conroe during extreme events. “We’ve got six feet of buffer that we can use,” said Raley. “Our operating protocol helps balance lake-level rise upstream and outflows downstream.”

As the water in the lake rises, SJRA must raise the gates. Still, rising water indicates that more water is coming in than going out…at least temporarily.

In extreme events, SJRA could certainly use even more stormwater storage. (But that would require pre-releasing water. Raley describes the constraints on pre-release several slides further down.)

Areas north and east of Lake Conroe received about half a year’s rain in a few days, testing the limits of the system that Raley described. It wasn’t just the amount of rain. It was also the intensity.

The basin wide average for May 2nd, for instance, approached 7 inches.

The lake at at FM1375 received more than an inch (or close to) it in several 15-minute periods. At that same location, they also received three inches in one hour.

It’s also important to realize that SJRA came into this event coming off another heavy rain. Note how the solid black line below (at the left) was just starting to return to normal when it suddenly peaked.

Note also the steepness of the rise when the black line turns up. “In a ten hour period, we went from 8,000 to 72,000 cfs,” said Raley. “That is fast. Very fast.”

The backline represents the inflow and the blue line represents the outflow. The rapid rise caused operators to open the gates wide at first. However, they also reduced the outflow when the inflow dropped. The two curves follow each other.

Inflow Higher than Harvey

The peak inflow during that rapid rise exceeded the peak inflow rate during Harvey.

The map and tables on the right indicate the peak flows coming from each tributary into Lake Houston.

Note how peak inflows from Lake, Spring and Cypress Creeks on the west were fractions of the volume coming from Lake Conroe.

Pre-Release Capabilities Constrained

Raley finished his presentation with a discussion of pre-release as a possible mitigation measure. The headline below says it all. Gone are the days of seasonal lowering.

At 700 cfs, the permit limit, Raley says it would take weeks to lower the lake. But weather predictions are not accurate that far in advance.

And if the storm misses Lake Conroe, a big release from the lake could make flooding in Lake Houston worse – especially if the storm misses Lake Conroe to the south.

So the SJRA tosses the responsibility back to the City of Houston, They make the City call for the water (out of its share of the lake) if the City wants Conroe lowered

Conclusion and Insight

Raley’s presentation won’t make flood victims feel better. But it may help them understand how difficult managing floods can be.

The important thing to take away from this is that there’s room in Lake Conroe for temporary storage of stormwater. And releasing that water so that it reaches populated areas downstream before or after the peaks coming from other tributaries will be the key to minimizing flood damage.

For instance, releasing a smaller amount after a larger peak has already passed won’t flood any more homes.

Remember, flood peaks are not necessarily additive. You can’t automatically assume that all peaks will hit at the same time and pile on top of each other.

I’m sure more knowledge can be acquired from close examination of this event. For instance, one of the big differences between this storm and Harvey was the downstream representation on the SJRA board by Mark Micheletti.

But Micheletti is the only downstream representative on a seven-person board. lf that continues, you can bet no substantial changes will be made in the long-term operation and policies of Lake Conroe.

Another thing to look at is whether keeping Lake Conroe at slightly lower levels during wet seasons would give dam operators more temporary storage, and thus protect more homes and businesses both upstream and down.

Posted by Bob Rehak on 5/24/24

2460 Days since Hurricane Harvey

All River Levels Falling, Flood Danger Over, But…

May 21, 2024 – After a second round of May floods (and the third this year), all river levels are falling today. The East Fork, West Fork and main stem of the San Jacinto River are finally falling this morning. So are the water levels in Lake Conroe and Lake Houston.

But sedimentation will likely be a problem when floodwaters totally recede.

Gage Readings For Lake Conroe

The gates at Lake Conroe are still open, but only releasing 1,599 Cubic Feet per Second (CFS). That’s about a twelfth of what the San Jacinto River Authority released at the peak of this second wave of May floods.

The graph below shows that the lake level is slowly approaching its normal conservation pool of 201 feet.

Note distances to flowage easement and top of dam. Homes around lake should be built above flowage easement.

All Gage Readings on West Fork Falling

In response, the West Fork at US59 fell below flood stage yesterday evening and continues to fall.

River Grove Park is draining, but the soccer fields are not yet playable.

River Grove Park draining on 5/20/24 at 5PM after flood peak passed

At West Lake Houston Parkway, the West Fork is well within its banks and falling.

Readings on East Fork

Upstream on the East Fork at SH105, the East Fork crest has passed and the river continues to fall.

At FM2090, the East Fork is 4 feet below flood stage and falling.

The East Fork fell below flood stage yesterday afternoon at FM1485 and continues to fall.

Lake Houston and Below

At the FM1960 bridge over Lake Houston, the level continues to fall well below flood stage, but is still about a foot above normal.

At the Lake Houston dam, water levels are also falling, but the lake is also about a foot above the spillway.

Floodwaters are still being released from the lake via both the gates and spillway.

The gates can release 10,000 CFS. That means about another 7,500 CFS are going over the spillway.

Downstream, on the main stem of the San Jacinto at Highway 90, the river is well below flood stage and continuing to fall.

West Fork Still Flowing Through Abandoned Sand Pit

That’s all great news. But the West Fork is still flowing through an abandoned sand pit near the Hallett Mine. You can see the impact at the confluence of the West Fork and Spring Creek.

Confluence of Spring Creek (left) and West Fork San Jacinto (Right) on 5/20/24 at 5 PM.

Can Water Moving at 5 MPH Transport Sand?

I measured debris coming out of the pit. It was moving at approximately 5 miles per hour (MPH).

Despite what some miners claim, 5 MPH should be more than enough to carry sand downriver.

Below is an industry-standard graph that shows the speed necessary to erode, transport and deposit sand/sediment of different particle sizes. Hydrologists and geologists call it a Hjulström curve, named after Filip Hjulström (1902–1982), the man who developed it.

After converting centimeters per second to miles per hour, I superimposed the speed of the river as a blue line over the graph.

The scientific Unified Soil Classification System defines sand as particles with a diameter of 0.074 to 4.75 millimeters. I rendered that range in red at the bottom of the chart.

Blue indicates speed of water. Red indicates range of sand sizes.

Floodwater moving at 5 MPH can transport the entire range of sand sizes according to the Hjulström curve. You can see it in the photo above.

The abandoned pit captured by the river is about a mile long and a half-mile wide.

The river will need to recede before we can see exactly how much moved down to the West Fork between Humble and Kingwood, or settled at the mouth of the river near Lake Houston.

In fairness, some of the sediment deposited downstream came from natural erosion from riverbanks. But there was also unnatural erosion from development and (I have heard) other mines. It is impossible to apportion responsibility precisely.

What we can safely say is that sand mining practices have increased sedimentation downstream and few people seem eager to fight the industry … even as we get ready to launch another round of dredging that will cost taxpayers $34 million.

Posted by Bob Rehak on 5/21/24

2457 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.

West and East Forks of San Jacinto Flooding Again

May 19, 2024 – For the second time this month, the West and East Forks of the San Jacinto River are flooding. The East Fork crested last night about 1.5 feet below the prediction. However, the West Fork is still rising at US59. Parts of River Grove Park and the turnaround under US59 are already flooded. And the National Weather Service predicts floodwaters will go even higher.

Meanwhile, the West Fork continues to run through an old Hallett sand pit that was sold in January.

Here’s what you can expect if you live near the rivers.

East Fork Crest Moving Toward Lake Houston

Low-lying areas along the East Fork began flooding yesterday at FM1485. Earlier, the East Fork flooded near Cleveland and Plum Grove. As the crest moves downriver, it is affecting communities differently. Exactly how depends on many factors, such as the conveyance of the river at different points, sediment accumulations, proximity of homes to the river and more.

Yesterday, water was coming across part of FM1485 where it crosses the East Fork and parallels SH99. Today, the entire east bound section of FM1485 was blocked by floodwaters.

East Fork San Jacinto at approximately 4:30 PM on 5.16.24
East Fork San Jacinto at approximately 4:30 PM on 5.16.24

As of 6 PM, May 19, floodwaters are declining in this reach of the river. The crest has moved downstream toward Lake Houston.

Harris County’s Flood Warning System shows the river crested last night but was still well above flood stage as of noon today.

Farther upstream, at FM2090, the river has already returned to its banks.

All this is the result of another 3-5″ of rain falling earlier in the week upstream in the watershed on grounds that were already saturated from torrential rains and flooding earlier this month.

NWS Issues Flood Warning for West Fork until Tuesday Morning

While the East Fork is falling at this hour, the West Fork is still rising. At 1:34 PM Sunday, the National Weather Service issued a flood warning for the West Fork near Humble affecting Harris and Montgomery Counties.

Communities affected include: Porter, Sendera Ranch Road, Conroe, Kingwood, Humble, Sheldon.

Only minor flooding is forecast.

National Weather Service Flood Warning

NWS will issue its next statement Monday morning at 7:45 AM CDT.

The FLOOD WARNING WILL REMAIN IN EFFECT UNTIL LATE TUESDAY MORNING.

IMPACTS: At 49.3 feet, minor lowland flooding begins in the vicinity of the gauge at US59. The north side turnaround at US 59 begins to flood. Low points in surrounding areas also begin to flood.

At 12:45 PM CDT Sunday, the river had risen to 49.2 feet.

 Bankfull stage is 45.3 feet.

The river will crest at 49.7 feet just after midnight tonight. It will then fall below flood stage late tomorrow evening.

Flood stage is 49.3 feet.

This afternoon, the turnaround under US59 was just beginning to flood. The parking lots and part of the roadway were already underwater.

Far side of sandbar in middle is normally the river bank.

At 5 PM, the soccer fields, picnic area and boat launch at River Grove Park were also partially underwater. And water was rising quickly.

Picnic area and boat docks at River Grove underwater and going deeper tonight.
Soccer fields, also at around 5PM
River still rising. Minor flooding expected through Tuesday.
Sand Mine Area Upstream

Farther upstream, the West Fork was still ripping a hole through an abandoned Hallett sand pit that the company sold to a real estate developer in January.

River is now flowing through the abandoned pit (right) instead of following the normal arc of the river (left) around the pit. Note trail of foam. It moved at around 5 mph.

This breach appears to have widened significantly in recent days. If it remains open and this pit becomes the new course of the river, it’s possible that the entire pit could become public property, just like the river is now.

On the other side of the river, Hallett filled in the trench that was releasing sludge from its settling pond last Friday afternoon.

Trench on perimeter of Hallett Mine that was releasing sludge into river on Friday afternoon has been filled in.

Lake Report

As of 7 PM, the SJRA is releasing 5,325 Cubic Feet per Second (CFS) from Lake Conroe. The lake is almost back to its normal level – within .67 feet of 201. And no rain is in sight. That’s good news. Releases should continue to go down.

Screen capture from SJRA website at 7:15PM.

Throughout this event, SJRA has balanced inflows and outflows to the degree that it can. The rate they show above is about half of what they released earlier in the weekend.

Lake Houston, however, is getting more, not less water. It is still about two feet above normal and discharging water via its gates and spillway. Total discharge is 34,015 CFS. Of that, the gates can release only 10,000 CFS. The other 24,000 CFS goes over the spillway.

Screen capture from Coastal Water Authority as of 7:15 PM.

Comparing the two numbers on the right, shows us that the flood risk is shifting to the Lake Houston Area now.

Of the 11 watersheds that send water into Lake Houston, SJRA controls only Lake Conroe. The East Fork has no flood control. But that’s a story for another time.

Posted by Bob Rehak on 5/19/24 at 8PM

2455 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.

SJRA Reducing Lake Conroe Release Rate

May 3, 2024 – As of 10 PM last night, the level of Lake Conroe had declined slightly for several hours. That indicates inflows are now less than outflows. Accordingly, San Jacinto River Authority Board Member Mark Micheletti worked out an agreement with the SJRA General Manager to start reducing the lake’s release rate.

By midnight the release rate was down from 69,585 cubic feet per second (CFS) to 64,797. And the lake level was down from 205.13 to 204.79.

This post contains information about the new release strategy, updated river and weather forecasts, plus a list of stunning rainfall totals from yesterday.

New Lake Conroe Release Strategy

During Harvey, many downstream residents felt the SJRA released too much for too long to return the lake to normal as quickly as possible.

The new agreement reached late tonight will have dam operators lowering the release rate in 2500 CFS increments. They will then wait two hours to see if the water level is increasing or decreasing, and adjust the next increment accordingly.

This strategy lets them delay additional decreases if necessary. For instance, if new heavy rainfalls increase inflows.

Dam operators still have the flexibility to release more if necessary. But it avoids leaving the release rate too high for too long when unnecessary.

All things considered, this strategy should protect downstream residents as much as possible. It also gives Lake Conroe operators a safety margin.

No Significant Changes to Flood Forecasts Since This Afternoon

As of 9:31 PM, Harris County Meteorologist Jeff Lindner had no changes to ongoing river forecasts. He emphasized that significant flood waves will continue moving down the East and West Forks of the San Jacinto into the weekend.

New Weather Forecast Reduces Rainfall Risk

Compared to yesterday’s weather forecast, however, Lindner also revised the expected overnight rainfall downward.

“Expect a mostly calm night with a low-end chance of a few showers toward morning. With heating on Friday and the approach of another thunderstorm complex from North Texas, there will be an increasing chance of rainfall during the day,” he said. “At this time. this complex of storms looks fairly progressive during the afternoon hours, but there is some uncertainty on how the storms evolve and how fast they cross the area.”

He says that additional rainfall amounts of 1-2 inches with slightly higher isolated totals can be expected on Friday. This additional rainfall is included in the river forecast models and should not greatly alter the current river forecast.

See river forecast summaries below.

East Fork San Jacinto River at New Caney (FM 1485)

Mandatory evacuation is still in effect for the eastern side of the river from FM 1485 to Lake Houston.

“Forecasted water levels will rise 7 feet higher than earlier this week. Structures on the ground will be flooded to rooftops levels,” says Lindner. “Elevated structures will be flooded. For reference, the forecasted water level is 4 ft below Harvey.” Similar to earlier this week, the rapid rise of several feet is expected late Friday into Saturday.

Impacted subdivisions: 
  • Idle Wilde
  • Idle Glen
  • Cypress Point
  • River Terrace
  • Magnolia Point
  • Northwood Country Ests
  • Low-lying eastern portions of Kingwood, such as:
    • Riverchase
    • Woodstream
    • Woodspring Forest
As of Thursday at 9 PM

West Fork San Jacinto River at Humble (US 59)

The river will rapidly rise from upstream inflows. It will reach major flood levels and peak near 62 ft on Saturday. Widespread low-land flooding will occur. It will likely impact lower areas in West Fork subdivisions such as:

  • Belleau Woods
  • Rivercrest
  • Northshore
  • Forest Cove 
  • Kings River Estates
  • Atascocita Shores
  • Kings Point
  • Kings Harbor
  • Kings River
  • Kingwood Greens
  • Fosters Mill
  • Kingwood Lakes
  • Barrington
  • Trailwood
  • Deer Ridge Estates

Kingwood residents should expect flooding of streets and structures near the East Fork, West Fork, and their tributaries.

Harris County is revising a potential inundation map that circulated Thursday on Facebook. Lindner says to expect the type of flooding we saw during the Memorial Days storm in 2016.

The following areas will be completely flooded with several feet of water: Deerwood Country Club, Deer Ridge Park, River Grove Park, Kingwood Country Club.

Elevated residents near the river should be prepared to be cut-off through the weekend if they don’t evacuate.

As of Thursday at 9 PM

West Fork of the San Jacinto River at I-45 

Major flooding is imminent upstream and downstream of I-45 including large portions of River Plantation and portions of Woodloch downstream to SH 242 and SH 99. Flows may approach the I-45 bridge deck. The current forecast is about 1 ft below Harvey recorded levels.

As of Thursday at 9 PM

San Jacinto River Below Lake Houston 

Major flooding is expected at all locations along the lower portions of the river.

Rio Villa will be completely inundated and cut-off and well as low lying in the river bottom around Highlands and HWY 90.

High velocity flows may damage vessels and barges near I-10 and result in loss of mooring.  

Flow may approach the I-10 river bridge west of the river crossing. Additionally, high flows will result in the suspension of Ferry service.

As of Thursday at 9 PM

Spring Creek

According to Lindner, the creek is rising on the upper end due to flows from Waller and Montgomery Counties. Minor flooding is in progress along the upper portions of Spring Creek at Hegar Rd. Water levels along the creek are high, but any flooding is minor and to rural areas near the creek. 

Willow Creek 

Willow Creek has crested and is slowly falling.

Yesterday’s Storm: Gage Readings

The storm that swept through southern Montgomery and northern Harris Counties yesterday dropped impressive amounts of rainfall.

Harris County Flood Control District released the following totals at 7 PM Thursday.

  • 8.24 in. – 1050 Spring Creek @ I-45
  • 8.2 in. – 1320 Willow Creek @ Kuykendahl Road
  • 7.76 in. – 755 San Jacinto River @ Lake Houston Pkwy
  • 7.2 in. – 785 Peach Creek @ FM 2090
  • 7.12 in. – 790 East Fork San Jacinto @ FM 1485
  • 6.92 in. – 795 East Fork San Jacinto @ FM 2090
  • 6.8 in. – 765 San Jacinto River @ SH 99
  • 6.64 in. – 1745 Cedar Bayou @ FM 1960
  • 6.6 in. – 1960 Luce Bayou @ SH 321
  • 6.12 in. – 770 San Jacinto River @ SH 242
  • 5.88 in. – 780 Caney Creek @ FM 2090
  • 5.76 in. – 1040 Spring Creek @ FM 2978
  • 5.64 in. – 1940 Luce Bayou @ FM 2100
  • 5.48 in. – 1340 Willow Creek @ SH 249
  • 5.12 in. – 1056 Mill Creek @ FM 1774
  • 5.04 in. – 1950 Luce Bayou @ SH 99
  • 5.0 in. – 1080 Spring Creek @ Decker Prairie-Rosehill Road
  • 4.96 in. – 760 San Jacinto River @ US 59

Locations Out of Banks, Flooding Likely

    HCFCD also reported that the following streams/channels were out of their banks and flooding was likely.

    • 710    San Jacinto River @ Rio Villa
    • 720    San Jacinto River @ US 90
    • 740    Lake Houston @ FM 1960
    • 760    San Jacinto River @ US 59
    • 780    Caney Creek @ FM 2090
    • 785    Peach Creek @ FM 2090
    • 790    East Fork San Jacinto @ FM 1485
    • 795    East Fork San Jacinto @ FM 2090
    • 1054    Mill Creek @ FM 1486
    • 1074    Walnut Creek @ Joseph Road
    • 1084    Threemile Creek @ Joseph Road
    • 1090    Spring Creek @ Hegar Road
    • 1195    Mound Creek @ FM 362
    • 1950    Luce Bayou @ SH 99

    Flooding Possible

    The following streams were still in banks, but flooding was possible.

    • 755    San Jacinto River @ Lake Houston Pkwy
    • 765    San Jacinto River @ SH 99
    • 770    San Jacinto River @ SH 242
    • 796    East Fork San Jacinto @ SH 105
    • 1050    Spring Creek @ I-45
    • 1055    Bear Branch @ Kuykendahl
    • 1076    Birch Creek @ Riley Road
    • 1086    Threemile Creek @ FM 362
    • 1110    Cypress Creek @ Cypresswood Drive
    • 1186    Live Oak Creek @ Penick Road
    • 1190    Little Mound Creek @ Mathis Road
    • 1320    Willow Creek @ Kuykendahl Road
    • 1340    Willow Creek @ SH 249
    • 1740    Cedar Bayou @ US 90
    • 1745    Cedar Bayou @ FM 1960
    • 1960    Luce Bayou @ SH 321
    • 2200    Houston Ship Channel @ Juan Seguin Park

    Resources for More Information

    To see:

    If in doubt about whether you will flood, remember. Better safe than sorry. If you evacuate needlessly, the most you lose is a day or two. But if you don’t and you flood, you could lose everything.

    Posted by Bob Rehak on 5/3/24

    2439 Days since Hurricane Harvey

    Lake Conroe Release Rate at 90% of Harvey

    5/2/24 at 4:30 PM – The San Jacinto River Authority (SJRA) is releasing water at the rate of 69,545 cubic feet per second (CFS from Lake Conroe. That’s down a couple thousand from the 71,835 they released earlier this afternoon, the second highest release rate ever – 90% of the all-time record of 79,000 CFS during Hurricane Harvey.

    At that rate, NOAA predicted the San Jacinto West Fork at US59 would peak at 62.4 feet. Since then, they’ve reduced that back a bit to 62.2.

    However, the level of Lake Conroe is still rising slightly. It stands at 205.13 MSL (mean feet above sea level) as of 4:30 PM.

    And local leaders including Houston Mayor John Whitmire, State Rep. Charles Cunningham and City Council Member Fred Flickinger met in Kingwood to plan emergency response with first-responders.

    More Rain on Way

    The level of Lake Conroe is up significantly since this morning. And another rain storm is headed our way tonight. The National Weather Service predicts a 40% chance of more thunderstorms tonight. Anything that falls will be on top of almost 7 inches of rain received in the Kingwood area earlier today.

    Flood watches and warnings remain in effect at the present time. Any new rain will fall onto already saturated soils, resulting in rapid runoff.

    SJRA Pushing Up Against Limit

    But the SJRA is running out of room. At 207, they flood Lake Conroe homes and endanger the dam, according to Mark Micheletti, an SJRA board member who lives in Kingwood.

    Micheletti has demanded that SJRA operators throttle back releases as soon as they stabilize the Lake Conroe’s level. The SJRA hopes to keep a safety margin by not letting the lake level get above 206, but nature, not engineers will make that call.

    Meanwhile, the uncertainty has many Kingwood people in panic mode wondering whether they should evacuate. I’ve been deluged (pardon the pun) with requests for information.

    Whitmire Visits Kingwood to Plan Flood Response

    Houston Mayor John Whitmire came to Kingwood this afternoon to meet with first responders and area leaders. He wanted to personally see the situation and assess what the area needs. He met with Fire Chief Samuel Peña, first responders, State Representative Charles Cunningham and City Council Member Fred Flickinger at Fire Station 102 on West Lake Houston Parkway.

    CM Fred Flickinger (center) met with Mayor Whitmire (right), Chief Samuel Peña (left) and other first responders at Fire Station 102 this afternoon on West Lake Houston Parkway.

    Peña emphasized the need for vehicles to stay out of high water. The fire department had already made numerous high water rescues today.

    State Representative Charles Cunningham (left) also helped plan the emergency response.

    At the meeting, Whitmire also said that he had discussed evacuation orders for certain subdivisions with Harris County Judge Lina Hidalgo. After Harvey, “communication with residents” and “warning time” were identified as two of the primary things officials needed to improve.

    Current East Fork Predictions and Evacuation Orders

    According to Harris County Meteorologist Jeff Lindner, the County has issued evacuation orders for the east side of the East Fork San Jacinto from FM1485 to Lake Houston. (Lake Houston Park is on the west side.) Forecasted water levels will rise 7-8 feet higher than earlier this week. Structures on the ground will be flooded to rooftop levels. Elevated structures will be flooded.

    For reference, the forecasted East Fork water level is 3 ft below Harvey.

    Impacted subdivisions: 
    • Idle Wilde
    • Idle Glen
    • Cypress Point
    • River Terrace
    • Magnolia Point
    • Northwood Country Estates

    Current West Fork San Jacinto Predictions and Warnings

    The West Fork is rapidly rising from upstream inflows. It will reach major flood levels and will rise to near 62 ft on Saturday. Widespread low-land flooding will occur impacting the following subdivisions:

    • Belleau Woods
    • Rivercrest
    • Northshore
    • Forest Cove
    • Kings Point
    • Atasocita Shores

    In Kingwood, Lindner expects flooding of streets and the lowest structures nearest the river. He also predicts backwater impacts along the tributaries. That means high river levels could force water in channels and tributaries to back up.

    The following areas will be completely flooded with several feet of water: Deerwood Country Club, Deer Ridge Park, and Kingwood Country Club.

    Elevated residents near the river should be prepared to be cut-off through the weekend.

    I have queried HCFCD about the list of subdivisions above. It seems incomplete. But I have not yet heard back.

    San Jacinto River Below Lake Houston

    Major flooding is expected at all locations along the lower portions of the river.

    Rio Villa will be completely inundated and cut-off. 

    High velocity flows may damage vessels and barges near I-10.

    Flow may approach and potentially reach I-10 on the west side of the river.

    Real Time Inundation Monitoring

    To monitor what’s going on around you, Harris County Meteorologist Jeff Lindner suggests using the Real-Time Inundation Mapping Tool found in the Harris County Flood Warning System. From the home page, just click “Inundation Map” in the upper left tool bar, then zoom into the area of interest.

    As of 4:22 PM on 5/2/24. Note large areas already inundated.

    Easy Way to Find the Elevation of Your Home

    Don’t know the elevation of your home? Consult this post about how to find it in the USGS National Map.

    More updates later. SJRA may issue another statement at 8PM.

    Posted by Bob Rehak at 4:30 PM, Thursday, May 2, 2024

    2438 Days since Hurricane Harvey

    Lake Conroe Increasing Release Rate After Torrential Rain

    5/2/24 Noon Update: Since publishing this, Lake Conroe has continued to rise and the SJRA has increased the release rate to 66,100 CFS. – Heavy storms dumped 10-12 inches of rain in isolated areas north of Lake Conroe last night. Most areas experienced 5-7 inches. As a result, Lake Conroe has increased its release rate to 60,455 cubic feet per second and it could go higher.

    The area north of Lake Conroe has received more than 17 inches in the last week.

    Engineers are currently modeling several different scenarios. The current inflow is more than two times greater than the outflow. The current release rate is already the second highest in the history of Lake Conroe.

    Source: SJRA as of 10:00 AM 5.2.24.

    Current Situation

    According to Jeff Lindner, Harris County meteorologist, significant flash flooding is ongoing from north of HWY 105 to southern Montgomery County and the northern portions of Harris County.

    At 8:27 am, radar showed the storm had moved into northern Harris, and northern Liberty Counties.

    RadarScope Pro Screen Capture at 8:23 AM, 5.2.24, Orange indicates 5″.

    It dumped 6 inches of rain in my gauge in two hours. And the total is still climbing.

    Such high hourly rainfall rates result in street flooding. Lindner warned people not to travel unless absolutely necessary.

    According to Lindner, “There may be a break in the activity in the afternoon hours before another complex of storms arrives overnight into Friday morning with additional heavy rainfall. But confidence in the forecast is not high.”

    Impact of Rains

    “Significant rainfall has also occurred over the headwaters of the East Fork of the San Jacinto River. New flood waves will certainly be generated on both the East and West Forks of the San Jacinto River,” Lindner added. The same holds true for Lake Livingston and the Trinity River.

    The heavy runoff over already saturated grounds will migrate downstream Friday into the weekend. 

    The SJRA does not have a dam on the East Fork and can’t control it. Dam releases on the West Fork do not impact the East Fork, but do impact Lake Houston.

    Lake Conroe Release Rate Increasing, Max Uncertain

    Lake Conroe virtually quadrupled its release rate from 17,000 cubic feet per second (CFS) at 7 AM to 60,455 CFS at 9:45 AM.

    The lake level at 10:48 AM had reached 204.4 – 3.4 feet above normal.

    Mark Micheletti, San Jacinto River Authority (SJRA) board member, said that SJRA engineers are modeling several release scenarios. So the ultimate release rate is uncertain as of this writing.

    The flowage easement at Lake Conroe is 207. That’s the elevation at which homes start to flood.

    Some people will criticize the SJRA for not releasing more water sooner. However, it was not an easy call.

    Lake Houston was already flooding from the East Fork. And a massive release coming down the West Fork could have flooded homes.

    Micheletti added, “Hydrographs are useless in a situation like this because you don’t yet know what the release will be,” he added.

    During Harvey, the SJRA released 79,000 CFS. So, they are already at 75 percent of the devastating Harvey release rate.

    But even with that, the current release rate is only about one third of the estimated water coming into the lake. “So that’s our challenge,” said Micheletti. The release rate will almost certainly go higher.”

    The Harris County Flood Warning system showed that the San Jacinto West Fork is still within banks, but that likely won’t last long.

    Before the heavy rains moved south this morning, river gages on the East and West Forks were dropping slowly as floodwaters receded from earlier in the week. But we’re about to experience a second wave there.

    If you’re in a place that has flooded before, the safest course of action is to start developing an action plan now.

    River Predictions

    At 10 AM, Lindner released new hydrographs for the West Fork, East Fork, and the area below Lake Houston.

    West Fork

    As of 10 AM, 5.2.24

    A rise to flood stage will occur today with a rise above major flood levels on Friday. Widespread low land flooding near the river is expected. The forecast may need to be increased more because of the uncertainty over Lake Conroe releases.

    While there will be widespread low land flooding, the lowest structures in Kingwood are not impacted until over 60-62ft. Expect this level of water in the river to create backwater in tributaries that could lead to additional flooding.

    A reader sent in this photo of the new Northpark South development between the West Fork and Sorters-McClellan Road.

    NorthPark South already underwater from rains. 5.2.24 at 11 AM. Photo by Jody Binnion.

    East Fork

    A significant rise on the East Fork is expected as the upstream flood wave moves downstream. Forecasted water levels will reach 6-8 ft higher than earlier this week. This expected flood level will be higher than TS Imelda and will be similar to October 1994. Even elevated structures may be flooded, according to Lindner.

    Below Lake Houston

    Other Flooding

    As I write this, I have received word that Taylor Gully is flooding and parts of nearby streets are closed.

    White Oak Creek is also flooding. Royal Pines, the new development on White Oak at the northern end of West Lake Houston Parkway, has also flooded neighbors’ yards and a garage.

    Flash flooding is ongoing along Willow and Spring Creeks, which are rising rapidly. Flooding along these creeks is becoming likely. Widespread street flooding and some structure flooding is possible.

    A training band of thunderstorms will produce another 2-4 inches of rainfall on top of the already 4-6 inches that has fallen in these watersheds.

    Pardon the pun, but the situation is very fluid. Sometimes new information comes in faster than I can update it.

    I will post updates including photos when the rain lets up.

    Posted by Bob Rehak at 10:00 AM on 5/2/24

    2438 Days since Hurricane Harvey

    Phase 1 of Northeast Water Purification Plant Expansion Nears Completion

    According to a December 15 press release by the Texas Water Development Board, Phase 1 of Houston’s new Northeast Water Purification Plant expansion is nearing completion. Phase 1 will supply 80 million gallons per day of treated surface water to the residents of Harris County, Fort Bend County and City of Houston.

    Two more phases remain. Phase 2A will deliver another 80 million gallons per day to the same areas. Phase 2B will deliver 160. So the entire complex, when complete, will deliver another 320 million gallons a day. That’s in addition to the 80 million gallons per day the original plant delivered before expansion.

    Goals of Plant

    The Texas Water Development Board provided $1.9 billion for the Northeast Water Purification Plant expansion project, making it one of the largest in the country.

    The plant has two goals:

    • Provide water for a population that increases by almost a million people per decade.
    • Reduce groundwater usage and subsidence.

    Completion Estimated in 2025

    The TWDB did not provide a date for expected completion of the next two phases, but at a May 2023 community meeting, project managers estimated a completion date in 2025.

    Artist’s rendering of completed project, looking NNW. Expansion area outlined in orange.

    Satellite photo from May with substantially complete phase outlined in red.
    Phase 1 in center of plant now substantially completed. Original plant is on far right. Photographed in August 2023.
    Phases 2A and 2B still under construction. Photographed in August 2023. Looking south.
    Entire plant. Looking east across older area toward new construction. Lake Houston at top of frame.
    Plant’s new Intake Facility. Those twin pipelines are big enough to drive pickup trucks through.

    The Luce Interbasin Transfer Project is associated with the expansion of the treatment plant. The channel from the Trinity River will ensure a steady supply of water in Lake Houston as Montgomery County’s growth demands more water from Lake Conroe.

    Reducing subsidence is paramount for the region. Subsidence has been linked to flooding. In fact, a whole subdivision on Galveston Bay in Baytown became uninhabitable before the State created the Harris Galveston Subsidence District.

    Here’s its story.

    Posted By Bob Rehak on 12/18/23

    2302 Days since Hurricane Harvey