Tag Archive for: Montgomery County

Montgomery, Liberty Counties Still Have Not Adopted Minimum Drainage Recommendations

After Hurricane Harvey, Harris County Engineering examined regulations throughout the region and recommended minimum drainage standards to reduce future flooding in the region’s cities and counties. Harris County even offered to pay the cost of inventorying existing standards and having an engineering firm draft recommended revisions. But almost 2000 days after Harvey, only half of the area’s cities and counties have taken action. Among those not acting: Montgomery and Liberty Counties. Here’s a breakdown of who has done what as of January 18, 2023, according to Harris County.

Already Upgraded

Twenty took Harris County up on its offer. They have already successfully updated their drainage regulations. They include:

  • Cities of
    • Baytown
    • Bellaire
    • Bunker Hill Village
    • Deer Park
    • El Lago
    • Friendswood
    • Galena Park
    • Hilshire Village
    • Houston
    • Humble
    • Jersey Village
    • Katy
    • La Porte
    • Pasadena
    • Piney Point Village
    • Seabrook
    • Southside Place
    • Taylor Lake Village
    • Tomball
  • Waller County

Considered Updates But Haven’t Acted

Twelve had requested and received an analysis, but had not yet implemented recommendations. They include:

  • Cities of:
    • Hedwig Village
    • Jacinto City
    • League City
    • Missouri City
    • Nassau Bay
    • Pearland
    • Shoreacres
    • South Houston
    • Spring Valley
    • Webster
    • West University
  • Fort Bend County

Not Acting

Eight have not updated ordinances and regulations. These include communities that did not respond to and those that refused Harris County’s offer. They include:

  • Cities:
    • Hunter’s Creek Village
    • Morgan’s Point
    • Stafford
    • Waller
  • Counties:
    • Brazoria
    • Galveston
    • Liberty
    • Montgomery

In fairness, Montgomery County did hire a firm in August 2022 to update/revise its drainage criteria manual and subdivision rules. The scope of work included examining some of the recommendations below made by Harris County. But work was expected to take at least a year.

Recommendations for Minimum Drainage Standards

The minimum drainage standards recommended by Harris County included:

  • Use Atlas 14 rainfall rates for sizing storm water conveyance and detention systems.
  • Require a minimum detention rate of 0.55 acre feet per acre for any new development on tracts one acre or larger. However, single-family residential structures and accessory buildings on existing lots would be exempt.
  • Prohibit the use of hydrographic timing as a substitute for detention on any project, unless it directly outfalls into Galveston Bay.
  • Require “no net fill” in the current mapped 500-year flood plain, except in areas identified as coastal zones only.
  • Require minimum Finished Floor Elevation (FFE) of new habitable structures be established at or waterproofed to the 500-year flood elevation as shown on the effective Flood Insurance Study.

I would add one more to the list:

  • No clearing or grading before environmental and drainage studies are completed, and during grading, measures are taken to protect neighbors from runoff.

This seems to be particularly troublesome issue for those surrounding new developments.

Self Interest

Harris County Engineering originally positioned adoption of the minimum drainage standards as a condition for receiving partnership money from the 2018 flood bond.

Clearly, not everyone sees that has a powerful incentive. Those outside Harris County likely see little benefit, especially since the Equity Prioritization Framework has delayed funding in those areas.

Perhaps Harris County should have emphasized how adoption of the minimum standards could help reduce flooding for ALL people in the region – including those within Montgomery and Liberty Counties.

During heavy rains in late January, I received dozens of reports of flooding in Montgomery and Liberty Counties. As growth in surrounding areas explodes, lax regulations are starting to inflict suffering on those area’s own citizens.

They should adopt higher standards for their own benefit, not just Harris County’s.

Photo taken January 30, 2023 along Harris/MoCo border near San Jacinto West Fork after 1.32 inches of rain.

Posted by Bob Rehak on 2/5/23

1986 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.

Royal Pines Floods Neighbor on Less Than 1″ of Rain … AGAIN

On October 28, Royal Pines flooded a neighbor on less than an inch of rain. Two months later, on December 29th, the same thing happened again. The video below provided by the homeowner shows the volume of water funneled across her property by the developer.

Video from NW corner of Royal Pines

This video and the previous one from October demonstrate the dangers of clearcutting and redirecting drainage without first constructing sufficient stormwater detention capacity.

Altering Landscape Accelerates Runoff Toward Homeowner

The homeowner who shot the video lives adjacent to the left border in the photo below. Royal Pines has apparently sloped its property toward that corner where contractors will eventually build a stormwater detention basin.

Looking N across Royal Pines. This and other photos below taken on 1/3/23.

Land now slopes toward where video was filmed at left corner. But that area used to slope in the opposite direction. See details below from the USGS NATIONAL MAP and the developer’s plans.

Green arrow on left shows location of homeowner’s property. Red X within V-shaped contour shows exact location of low point (graph on right) before clearing and grading the land.

There used to be an 8-foot drop east of the homeowner’s property. But now, instead of water flowing directly north to White Oak Creek, it flows northwest.

The general plan for Royal Pines (below) shows the same V-shape in the proposed detention basin (upper left). The line represents the edge of the floodplain and confirms that the developer A) knew about the slope and B) changed it.

Royal Pines
Royal Pines General Plan.

Silt Fence, Trench Ineffective Against That Much Water

The video above and the photos below show that silt fence makes a terrible dam against even small rains funneling toward a point from such a large area.

Exercise in futility. A series of silt fences have done little to catch and slow the water...or the silt. Note erosion deposited in woods.
Looking south. The developer apparently tried to divert runoff racing toward the homeowner with a trench. But erosion from the barren land rapidly filled it in.
Runoff also collects at the entrance to Royal Pines. Looking ENE from the entrance at the northern end of West Lake Houston Parkway.

Unfortunately, the developer plans to build homes there, not another detention basin.

0.88 Inches of Rain Fell in Two Hours

The graph below from the Harris County Flood Warning System shows that .88 inches of rain fell in the two afternoon hours before the homeowner shot the video.

Homeowner shot video after first two bars on left.

The table below shows that that much rain in two hours constitutes less than a 1-year rainfall event.

atlas 14 rainfall probabilities
Atlas 14 rainfall probabilities for this area.

That’s consistent with actual observed events and climate records. According to the National Weather Service, on average, we can expect rainfalls greater than 1 inch 14 times per year in Houston. That’s about once per month.

Woodridge Village Revisited

The Montgomery County Engineer’s Office has reportedly asked the developer’s engineering company to revise its plans. The homeowner says that according to the engineer’s office, not even a 6-7 foot tall berm around that portion of the property would be enough to stop all the water flowing in that direction.

So, what lessons can we learn from this example? As with Woodridge Village, don’t clear and grade this much land before constructing detention basins!

The first sentence of Section 11.086 of the Texas Water Code states that “No person may divert … the natural flow of surface waters in the state, or permit a diversion … to continue, in a manner that damages the property of another…”

Posted by Bob Rehak on 1/13/2023

1963 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.

November Flood-News Roundup

Below is a roundup of flood news this week – seven quick stories.

Montgomery County Buyout Deadline Fast Approaching

The deadline for the current round of buyout applications in Montgomery County is November 30, 2022.

The Montgomery County Office of Homeland Security and Emergency Management still has money left in a Community Development Block Grant for Disaster Recovery (CDBG-DR). The U.S. Department of Housing and Urban Development (HUD) and the Texas General Land Office (GLO) allocated the money to buy out homes flooded during 2016 and 2017 (Harvey).

There are strict eligibility requirements; see the applications online. However, MoCo is now taking applications from homeowners who flooded repeatedly regardless of income level. Previously, the county was giving preference to low-to-middle income (LMI) families meet HUD’s LMI quotas.

While HUD does cap maximum buyout costs, Montgomery County offers several “credits” that can help people. Those include, but are not limited to special credits for seniors and veterans, and for moving expenses.

The county is hosting a series of meetings to help residents understand their options. More details to follow in a separate post on this subject.

Tammy Gunnels home in Porter flooded 13 times in 11 years before finally getting a buyout last year through the programs mentioned above.

Regional Flood Planning Group Draft Plan

The public comment period for the San Jacinto Regional Flood Planning Group’s draft plan closed on October 29th. Here’s an overview of their recommendations. One was developing detention on and channelizing portions of Spring Creek. The Bayou Land Conservancy (BLC), one of the Houston region’s leading conservation groups, had concerns with that.

BLC submitted this letter. It details the dangers of channelization to the 14,000 acres it preserves. In particular, BLC feels the report does not adequately consider erosion that could be caused by speeding up floodwaters. They say that detention and channelization projects could destabilize the entire natural system along Spring Creek. They urge more study on sedimentation and erosion before moving forward with construction.

The next step: the Regional Flood Planning Group will consider all comments received and modify the draft plan as needed.

$750 Million HUD Grant to Harris County

After promising to submit its $750 million Method of Distribution (MOD) to the GLO by the end of September, Harris County still has not yet submitted it. GLO first said it planned to allocate the money to Harris County in May, 2021 – 17 months ago!

The MOD is a plan that shows how Harris County would allocate the money. Who gets how much for what? MOD approval is necessary to ensure the County spends the money in accordance with HUD and GLO requirements.

The money could cover all under- and unfunded projects in the 2018 Flood Bond. But in April, Harris County’s new administrator assigned the task of developing the MOD to the Community Services Department instead of the Flood Control District – even though Community Services has had four leadership changes under Lina Hidalgo.

Community Services said that it planned to deliver the MOD to GLO by the end of September and publish the draft MOD by the end of October. Neither happened. The last response from Community Services was at the start of October.

At that time, the department head said the group had determined a “process” for developing the MOD. But they had yet to define any projects. For that, they were waiting for “direction from leadership.” As a result, $750 million that could mitigate flooding in Harris County is still sitting in Washington at HUD.

Meanwhile, GLO also notified H-GAC of a $488 million dollar allocation on the same day in May, 2021. H-GAC has already developed its MOD and gotten it approved. And H-GAC sub-recipients are reportedly already taking bids on projects.

There’s a lot of flood-mitigation money waiting in the wings that could accelerate Harris County projects. The longer Community Services waits, the more it places the money in jeopardy. Fifty percent must be spent in the next three years.

“Water Has a Memory”

New York 1 published a fascinating story about an ecologist tracing New York flooding back to its roots with old maps. The title: “A map of New York City before it was a city could provide answers to today’s flooding.”

The central figure in this detective story is Eric Sanderson. He cross-references current flooding issues with a historical chart of “the city’s buried, drained, filled-in or paved-over waterways.”

In every case, he says, the problems have the same roots. 

People built lives in places that used to be underwater. And water, he says, has a memory. 

“Maybe there was a wetland there, maybe there was a stream there, maybe there was a pond there, and people have forgotten,” Sanderson said in the interview.

We see this constantly in Houston. In one extreme case, a developer cleared property, filled in wetlands and THEN conducted an environmental survey.


All but a few of the 131 mini-homes at the Preserve at Woodridge are now framed out. The closer this site gets to completion, the more I question the accuracy of the engineer’s claim of only 66% impervious cover.

The Preserve at Woodridge will feature some homes as large as 660 square feet and four feet apart. Photo October 31, 2022.
Kids will love this area for Halloween. More candy per footstep.

Flood-Insurance Flap

The Houston Chronicle recently published an editorial about new flood Insurance rates designed to stanch financial hemorrhaging in the National Flood Insurance Plan. The title: “What happened to affordable flood insurance?”

For the first time this year, FEMA is trying to put flood insurance rates on an actuarial basis. But weening people off nationally subsidized insurance is proving difficult. The article claims some people have 500% rate increases even though increases are capped at a far lower rate.

While bemoaning the unintended consequences of well-intended reforms, the editorial proposes a solution: making flood-insurance rates “income based”!

One wonders about the unintended consequences of that. Will the availability of cheap flood insurance encourage building low-income housing only in the riskiest areas?

We shouldn’t forget that it was the availability of cheap flood insurance that encouraged building in flood-prone areas to begin with.

There may be no good solutions to this problem. Many feel government should have never have gotten involved in flood insurance from the start.

One insurance agent I talked to suggested this. “Worst case: offer buyouts to people who can’t afford flood insurance with the understanding that if declined, then there will be no more assistance for financial losses due to flooding.”

I personally favor a two-tiered public/private approach similar to Medicare. Cap the federally subsidized insurance at a level that stops the hemorrhaging. Then, let private insurers fill the gaps up to the full value of expensive homes.

This debate could take years.

New Netflix Series: High Water

Sally Geis, a former Kingwood resident, wrote me about a new Netflix show called “High Water.” It’s based on true events in 1997. It describes a massive flood that took place in Wrocław, Poland. The flood caused $3.5 billion in damages and put almost half of the city underwater.

However, it could have been smaller if one of the villages had allowed the incoming flood waters to be diverted onto their fields. Their “not-in-my-backyard” refusal and the disastrous individual and community consequences are the theme of the series. Sound familiar?

The acting and production design are first-rate, according to Geis. “It’s a story about a real disaster and real problems that can happen anywhere on the globe right now,” she says.

Click here for the trailer.


Posted by Bob Rehak on 11/4/22

1893 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.

Splendora Development Exploding

Splendora is exploding with growth. On FM2090 west of U.S.59 near the Splendora High School, two new developments have already cleared 598 acres and have another 611 to go. Together, they could easily quintuple the population of a rural town that only had 1900 residents in the last census.

Development Well Underway

I first covered this story in January. The developers have made remarkable progress since then. Townsend Reserve, Ltd. and Forestar USA, have built drainage, utilities, stormwater detention basins, roads and model homes on most of the land already cleared. Now, they’re building the first homes for sale. Rural, sleepy Splendora will soon change forever.

Here’s the layout and photos of work in progress.

Splendora Developments on 2090
Green = acreage under development. Red = not yet cleared. From Montgomery County Appraisal District.

Forestar USA has named its development Presswoods. Townsend Reserve USA has simply called its Townsend Reserve.

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Looking east along FM2090 at expanse of two developments. Splendora High School on right.

Closer Look at Detention Basins

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Close up from shot above. Two detention ponds in Presswoods by Forestar USA bracket Gully Branch. Gully Branch drains into Peach Creek and eventually the East Fork of the San Jacinto.
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Another Forestar USA detention basin in the foreground. Looking West.
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Looking NE at a fourth detention basin on Townsend Reserve that parallels Gully Branch.
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Entrance to Townsend Reserve from FM2090 on right. Note yet another long detention basin that parallels the entry road on the left. Looking NW toward FM2090.
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First of the new homes going up.

Three things strike me about these photos.

  • Stormwater detention basins everywhere you look. Let’s hope the volume is sufficient. Engineers based their calculations on pre-Harvey runoff estimates. As other developers clear additional forests beyond these, drainage assumptions could change radically.
  • Huge financial risk. As interest rates continue to climb, will there be buyers for these homes?
  • Vast expanse of forests surrounding the developments. They seem endless. But not for long.

People hoping to find a quiet life in the country are gobbling up the very thing they seek.

Maybe this is inevitable. Developers tell me that smaller lot sizes and higher density don’t allow them to preserve trees anymore. Builders just plant one in the front yard when they’re done.

Population Impact

It’s not exactly clear yet how many homes the developers hope to build here. But in the last census, Splendora’s population was only 1,900 people. Even if they just built 5 homes per acre on 800 developable acres and the average household size was 3, that would mean 12,000 people could live here – more than 6X the current population.

Posted by Bob Rehak on 10/10/22

1868 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.

MoCo Updating Drainage Criteria Manual, Subdivision Rules

Montgomery County (MoCo) Commissioners voted on 8/23/22 to update the County’s Drainage Criteria Manual and its Subdivision Rules and Regulations. Precinct 2 Commissioner Charlie Riley made the motion (item 16.C on the 8/23/22 Commissioners Court agenda).

Montgomery County Commissioners Court discusses new drainage and subdivision manuals in 8/23/22 meeting.

See the discussion in the MoCo Commissioner’s Court video. Select Item 16. The discussion starts at 3:12.

The previous Drainage Criteria Manual posted on the MoCo Engineer’s site is dated 1989, but appears to have some minor updates from 2019. The Subdivision Rules and Regulations for new developments date even further back, to 1984, although they too had new amendments and addenda incorporated in July, 2021.

MoCo hired Halff Associates to do the updating. Their fee: $302,000.

Welcome News

This is welcome news for people in northern Harris County. Drainage and engineering standards in MoCo have lagged those in Harris. That has created adverse downstream impacts even though developers may technically meet MoCo requirements. But the lower standards enable them to claim “no adverse impacts” when, in fact, there may sometimes be some.

Changes Could Reduce Flooding in MoCo and Harris Counties

Since Harvey, the Harris County Engineering Department and Flood Control District have worked to get surrounding counties to adopt five minimum drainage standards. They include:

Scope of Content Updates

The Scope of Work approved by MoCo Commissions last week shows that Halff will examine most, if not all, of these issues and more. The effort will evaluate and potentially update, at a minimum:

  • Hydrologic methodology (this includes hydrographic timing but is broader)
  • Detention sizing and outfall design
  • Open channel design frequency and requirements
  • Floodplain analysis.

Process for Updates

The scope of work also defines the process that Halff will follow. It includes:

  • Coordination with County engineering staff
  • Evaluation of existing manuals
  • Identifying dated criteria/information
  • Comparisons with neighboring counties practices (see below)
  • Revisions
  • Development of the new documentation
  • Stakeholder review and reporting
  • Presentation to Commissioners Court
  • Reporting approved changes to adjacent counties.

Work should take about a year.

Comparison with Regs in Other Entities

For the drainage Criteria Manual, Halff will compare criteria from TxDOT, Harris County, HCFCD, Waller County, Fort Bend County, and Brazoria County.

Halff will compare MoCo’s Subdivision Rules and Regulations to those in Harris, Waller, Fort Bend, and Walker Counties.

This is more good news for those in northern Harris County.

About Halff Associates

A source in the engineering community characterized Halff as a good company. He said, “The Montgomery County manual is in good hands….as long as they let Halff do the right things.”

Halff will work with the MoCo Engineer Jeff Johnson on the updates.

Subdivision Rules and Regulations

Neither the Scope of Work, nor Commissioners discussed specific recommendations for updates to Subdivision Rules and Regulations. But Commissioners did request an opportunity to discuss and review updates on both manuals before they came back to Commissioners Court for final approval.

Immediate Impact

One former MoCo employee said, “There is still the hurdle of the court adopting the updated standards. Expect a rush of drainage studies to be submitted in the next year so they can be grandfathered in.”

We saw this in the City of Houston (CoH), for instance, with the Laurel Springs RV Resort. The detention pond in that development is half the size required by new standards. CoH permitted it one day before the new standards went into effect.

Related News: MoCo Floodplain Administrator Office

At about 40 seconds into the video for Items 17 and 18 on the agenda, the Commissioners approved a motion to have Precinct 2 Commissioner Charlie Riley oversee MoCo’s Office of the Floodplain Administrator. Reasons for the change were not clear. Discussion happened in Executive Session.

All we have to go by is the outcome. And the outcome shows that MoCo is bringing the Office of the Floodplain Administrator – for the whole county – under the direct, political control of one precinct commissioner. Interesting.

Posted by Bob Rehak on 8/28/2022

1825 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.

Tree Muggers for Tree Huggers: The Irony of Royal Pines

The “Tree Muggers” at the new Royal Pines subdivision in Montgomery County at the north end of West Lake Houston Parkway continue their relentless and remorseless destruction of trees. How ironic considering that the name implies the developer will market homes to Tree Huggers! Perhaps they:

  • Feel the name will blind customers to the reality.
  • Will offer to plant a ceremonial sapling at closing.

Houston Business Journal said Royal Pines will ultimately feature between 350 and 450 homes targeted at first-time home buyers.

Construction Status on 7/30/2022

Here’s what Royal Pines looked like at the end of July 2022.

Dead tree limbs stacked two stories high awaiting removal. Newly cleared area is at top of frame to the left of Country Colony in the upper right.
Higher angle shows proximity to the Triple PG sand mine in the background. White Oak Creek runs between the mine and the subdivision.
Looking NE toward Triple PG sand mine in background. The extent of clearing as of the end of July 2022.
Looking SSE across Royal Pines toward the current terminus of West Lake Houston Parkway.
Looking SW. The distant clearing is Woodridge Village where similar clearcutting contributed to the flooding of hundreds of homes in Elm Grove and North Kingwood Forest twice in 2019.
Same direction, but closer and higher. Note the contrast with previous development practices that tried to build homes among the trees.

Ever-Widening Clearing

Compare what the development looked like:

Tree Muggers’ Plans

The following links will show you the general plan and layouts for the first three sections:

Old Floodplain Maps Will Put Unsuspecting Buyers at Risk

Note the dotted lines that snake their way through the top of the development. Those represent the 100- and 500-year floodplains.

Notice how a large part of the development is in “Zone X (Shaded).” That’s the area between the limits of the base flood (100-year or 1% annual chance) and the 0.2-percent-annual-chance (or 500-year) flood. I counted more than 80 homes in that zone. I also see six already INSIDE the 100-year zone.

Keep in mind that these flood zones are based on PRE-Harvey estimates. FEMA shows that Montgomery County last mapped this area in 2014. When FEMA approves new POST-Harvey flood maps in the next few years, those zones will expand to take in more of the subdivision. 

In Harris County, MAAPnext is revising maps based on higher rainfall probability statistics and current changes in development. And a lot of development has occurred upstream of Royal Pines on White Oak Creek.

MAAPnext advises that, in general, new flood maps will show floodways expand into the 100-year flood zone and the 100-year expanding into 500-year by about 50%.

This is the same problem I talked about yesterday with the Kingland West development in Harris County at the Grand Parkway and the East Fork.

We won World War II in less time than it’s taking to release these new flood maps. Ironically, by the time they’re released, the Tree Muggers will have already invalidated the basis for the new maps. And thus, the cycle of flooding continues.

Posted by Bob Rehak on 7/30/2022

1797 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.

Montgomery County Allocated $60 Million in Harvey Mitigation Funds

The Houston-Galveston Area Council of Governments (H-GAC) has allocated $60 million to Montgomery County. The money comes out of a $488 million of Harvey flood-mitigation funds previously allocated to HGAC by the U.S. Department of Housing and Urban Development (HUD) through the Texas General Land Office (GLO). The $60 million is the single largest allocation to any governmental entity in the region out of the $488 million pot.

50% Committed to LMI Areas

At least 50% of the money must go to low-to-moderate income (LMI) areas in Montgomery County. The GLO has determined that MoCo plans meet HUD rules and conditionally approved the allocation.

However, things could still change and Montgomery County has not yet received the money.

According to H-GAC, the conditionally approved preliminary method of distribution (a plan for whom gets how much) is still pending acceptance by eligible entities and is subject to change through a published re-allocation process. A complete list of eligible activities is available in the Texas General Land Office (GLO) guidelines for the Regional Mitigation Program – Council of Governments Method of Distribution (COG MODs). Depending on changes, another 30-day public comment period may necessary, according to the GLO.

Where, How MoCo Will Spend the Money

I reached out to the Montgomery County Judge’s office to see how MoCo hopes to spend the money. Jason Millsaps replied, “Montgomery County will attempt several projects with these funds as soon as final approval has been granted.”

Millsaps continued, “In East County, we will work to de-snag, de-silt and remove vegetation that hinders flow from the Peach Creek, Caney Creek, White Oak Creek, and East Fork of the San Jacinto River. We will do the same for Lake Creek and Stewart Creek in Central/North County, with additional bank armor going in for Stewart Creek near the River Plantation Subdivision.”

Those should reduce flooding in Montgomery County. This flood map shows the areas most affected by repeat flooding in the county.

And this map shows the location of each creek and how much floodwater each conveyed during Harvey.

Peak Flows During Harvey
Peak flows in the San Jacinto Watershed during Hurricane Harvey

Posted by Bob Rehak on 7/12/22

1778 Days since Hurricane Harvey

Harris County Commissioners Reaffirm Need for Minimum Drainage Standards in Region

On Tuesday, April 5, 2022, Harris County Commissioners Court reaffirmed the need for minimum drainage standards in the region. The program called “Fix Flooding First,” was started in 2020 by the Harris County Engineering Department. It is designed to help prevent flooding, not just fix it. The idea: to bring all municipalities and other counties that drain into Harris County to adopt minimum drainage standards.

Big Box Stores in Humble opposite Deerbrook Mall along US59 during Harvey. 130,000 cubic feet per second came downstream from Montgomery County which has declined to work with Harris County in adopting minimum flood regulations.

Altogether, the West Fork and East Forks of the San Jacinto with Peach and Caney Creeks, all of which drain through rapidly developing Montgomery County sent 300,000 cubic feet per second into the Lake Houston Area during Harvey.

To see how many square miles are being drained upstream from you, consult this map. Almost half of the watersheds in Harris County originate outside the county.

watersheds in Harris and surrounding counties
Watersheds in Harris and surrounding counties.

Seeking Agreement on Five Measures

Five minimum measures, recommended by the Office of the County Engineer and Harris County Flood Control District, include:

1. Use Atlas 14 rainfall rates for sizing storm water conveyance and detention systems.
2. Require a minimum detention rate of 0.55 acre-feet per acre of detention for any new development on tracts one acre or larger. A single-family residential structure and accessory building proposed on an existing lot is exempt from providing detention.
3. Prohibit the use of hydrograph timing as a substitute for detention on any project, unless it directly outfalls into Galveston Bay.
4. Require “no net fill” in the current mapped 500-year floodplain, except in areas identified as coastal zones only.
5. Require the minimum Finished Flood Elevation of new habitable structures be established at or waterproofed to the 500-year flood elevation as shown on the effective Flood Insurance Study.

Harris County Has Little Leverage

Harris County doesn’t have much leverage in this request. It can’t force neighbors to do anything. Compliance more or less depends on good will and a recognition that flooding in Houston and Harris County can affect the whole region negatively. Working together ultimately benefits everyone.

However, Harris County does have two small carrots. The County hired a consultant to review existing flood regulations in neighboring jurisdictions and make recommendations to bring them up to minimum standards. The county also can approve (or reject) partnership projects with those neighbors.

Mixed Results; No Change Since January

As of the start of this year, the program had met with mixed success.

  • 16 municipalities (including Houston, Humble) and Waller County had successfully upgraded their regulations.
  • 14 municipalities and Fort Bend County had completed the analysis of the regulations but not fully upgraded them yet.
  • 8 (four municipalities and four counties) did not respond to the offer of the analysis, refused it, or refused to participate.

As of last Tuesday, those results had not changed since January when I last reported on this program. The same municipalities and counties were in each category. Liberty and Montgomery Counties both fall into the last category (did not respond or refused).

Compliance list from January has not changed as of April 5, 2022.

Establish Precedent for Regional Cooperation Now

Harris County can spend billions on flood mitigation, but if upstream communities keep sending more water downstream, we may never see improvement. 

Ironically, all the upstream communities will be downstream from other developing communities in the future and may be in the same position that Harris is in today. It would be good to establish precedent for regional cooperation now that they could use themselves in the future.

Studies show that for every dollar spent on flood prevention, they can save five dollars on flood mitigation. That’s money that could go into improving the quality of services and infrastructure in communities….without forcing people through the trauma of flooding!

Posted by Bob Rehak on 4/7/22

1682 Days since Hurricane Harvey

New 1700-Acre MoCo Development Claims “No Adverse Impact,” But Doesn’t Study Other Areas

A new 1700-acre development called Madera at FM1314 and SH242 claims it will have “no adverse impact” on surrounding areas. However, to determine this, the authors of the drainage impact analysis used a controversial technique permitted by Montgomery County drainage regulations. It’s called “hydrologic timing.” The technique doesn’t take into account drainage from other developments in surrounding areas. Nor did it factor in the destruction of wetlands.

Outline of Madera Development (dotted line) just north of SH242 at FM1314). For reference, Artavia (mentioned below) lies under the legend.

The Problem with Hydrologic Timing

The theory behind hydrologic timing is that if you can get your water to the river before the peak of a flood arrives, then you aren’t adding to the peak. This might have “no adverse impact” if you were the only development in a watershed. But when you’re:

…everybody is racing to get their drainage to the river faster instead of slower. That could be shifting the peak for the entire watershed. A nearby 2,200-acre development called Artavia also used hydrologic timing to prove no adverse impact.

Example: Two Adjacent Developments Pile It On

Artavia, for instance, claimed that its drainage plan would get water to the West Fork 35 hours before upstream peaks arrived. Meanwhile, Madera (literally a few hundred feet away on the other side of SH242), claims it will get its peak to Crystal Creek 28 hours before that stream’s peak arrives. Crystal Creek empties into the West Fork just upstream from Artavia’s drainage.

Natural and man-made peaks for 100-year storm on left. Engineers will get water to creek twice as fast as nature.

So you could have potentially one peak on top of another and another, etc.

Neither development accounts for peak changes induced by the other in analyses.

Now multiply that times a hundred or a thousand developments and you see the danger.

Several years ago, residents pleaded with MoCo Commissioners to outlaw such “beat the peak” analyses for this very reason. But commissioners refused.

Eliminating Nature’s Detention Ponds

The land in question is low. The US Fish & Wildlife Service shows its dotted with wetlands – nature’s detention ponds.

Even the Montgomery County Appraisal District website shows Madera covered with swamp symbols and ponds.

As far as I can see, the drainage impact analysis supplied by engineers makes no attempt to compare the amount of natural detention to man-made detention.

When Does Real Peak Happen and Why Does It Matter?

Engineers claim they aren’t adding to discharge; they’re just shifting the peak. But because of all the development in MoCo in the last 40 years, it’s not clear when that peak from outside the development will really happen.

In fairness, Madera plans do show a number of detention ponds. But even with those, Madera will still add 16,300 cubic feet per second to the West Fork in a 100-year storm. And that’s just for Phase 1 of the development! That’s why engineers say below, “will not likely have an impact on peak flows…”

From documentation supplied to MoCo engineer’s office by Torres & Associates on 2/19/21

To put that volume in perspective, during the peak of Harvey, the SJRA says the nearby West Fork carried 115,000 CFS. So Madera will contribute 14% of Harvey’s volume at that point on the West Fork. And most people consider Harvey far more than a 100-year storm.

Problem with Higher Peaks

The hydrograph below shows how the peak on Brays Bayou shifted over time with upstream development. On the West Fork, this may already be happening.

Time of accumulation in Brays Bayou was cut in half over time, leading to higher flood peaks. From HCFCD, FEMA and Tropical Storm Allison Recovery Project.

In the last 20 years, HCFCD and its partners have spent more than $700 million on flood mitigation in the Brays Bayou watershed.

The safest strategy is for new developments to “retain their rain” until the peak of a flood has passed and then release it slowly. “Retain Your Rain” is the motto of most floodplain managers. If everyone did that, there would really be “no adverse impact.”

Delaying stormwater discharges, not accelerating them, is the safest strategy.

Faster Runoff, Faster Erosion

As stormwater approaches Crystal Creek, it will encounter a steep drop that requires the use of check dams and other measures to slow water down.

Mavera runoff as it approaches Crystal Creek (left) encounters a drop that could increase erosion if not mitigated properly.

Erosion during Harvey has already cost taxpayers more than $100 million in dredging costs and that total will go higher.

Aerial Photos Showing Work to Date

Wetlands no more. Looking east from over FM1314. Area in upper left has not yet been cleared but will be.

Land Consists Primarily of Wetlands

The hundreds of pages supplied by the Montgomery County Engineer’s Office in response to a FOIA Request show that this development tract consists “…primarily of evergreen and mixed forest and woody/herbaceous wetlands.” [Empasis added.] Yet the drainage analysis never again mentions that when it claims the development will have no adverse impact.

Looking west toward FM1314, which runs through middle of frame and US242 (upper left) Note drainage and clearing activities moving west. Area in upper right will also eventually be cleared. Note West Fork San Jacinto beyond SH242.
Looking north across drainage ditch. that bisects development (see below). Many of those trees will soon be gone. The northern half of the subdivision will look like the cleared area in the foreground.
Building homes over a swamp can lead to foundation shifting and cracking.
Drainage from the eastern half of Madera will flow through the concrete box culverts under FM1314 to the western half.
Looking west. Note standing water in forest between ditch and SH242 (out of frame on left).
Western half of development is now in initial clearing phase.
Map of development showing location of drainage ditch, Crystal Creek and San Jacinto (lower left). Virtually all cleared areas to date are below the blue dotted line which represents the drainage ditch. Area below the drainage ditch appears to represent less than half of the total area.

HCFCD Position on Hydrologic Timing

Harris County Flood Control has long lobbied to eliminate hydrologic timing in drainage analyses for the reasons mentioned above. However, Montgomery County Commissioners have not acted on the proposal.

Posted by Bob Rehak on 1/23/2022

1608 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.

What Does “No Adverse Impact” Really Mean in Drainage Studies?

New developments in many jurisdictions must demonstrate “No Adverse Impact” (NAI) in drainage studies before they can get construction permits. City and county engineers want to know the development won’t harm others before they approve plans. But what does “No Adverse Impact” really mean? It depends on the jurisdiction.

Meaning Varies

Most jurisdictions require that new developments won’t add to flooding. In Montgomery County, for instance, developers do this by comparing runoff pre- and post-development. If engineers can show that post-development runoff does not exceed pre-development runoff, then they get their permit.

Such studies focus primarily on water surface elevations. But the Association of State Floodplain Managers (ASFPM) has a much broader definition.

In their book, No Adverse Impact means that actions of any community or property owner, public or private, “should not adversely impact the property and rights of others.” 

An adverse impact can be measured by an increase in flood stages, flood velocity, flows, the potential for erosion and sedimentation, degradation of water quality, or increased cost of public services. 


Definition Should Apply Beyond Floodplain

According to ASFPM, “No Adverse Impact” floodplain management extends beyond the floodplain to include managing development in the watersheds where floodwaters originate. NAI does not mean no development. It means that any adverse impact caused by a project must be mitigated, preferably as provided for in the community or watershed-based plan.

Here’s a presentation that covers NAI at a high level. Some key points include:

  • Flood losses are increasing by $6 billion annually. That’s because current policies promote intensification in high risk areas. They ignore changing conditions, undervalue natural floodplain functions, and often ignore adverse impacts.
  • Even if we perfectly implemented current standards, damage will increase.
  • Floodplains change due to filling.
  • Current regulations deal primarily with how to build in a floodplain vs. how to minimize future damages.
  • NAI actually broadens property rights by protecting those adversely impacted by others.
  • Trends in case law show that Act of God defenses have been greatly reduced due to ability to predict hazards events.
  • Hydraulic models facilitate proof of causation.
  • Use of sovereign immunity has been greatly reduced in lawsuits.
  • Communities are most likely to be held liable not when they deny a permit, but when they permit a development that causes damage to others.

Where to Find More Information About NAI

ASFPM has extensive information on the guidelines for “no adverse impact.”  They include NAI How-to Guides For…

This 108-page PDF from ASFPM sums it all up in one easy-to-download file.

Recent Case Study of Adverse Impact

Earlier this week, I toured Plum Grove to survey flood damage from the January 8/9 rains.

Between Saturday afternoon on 1/8 and Sunday morning on 1/9, Plum Grove received about 6.9 inches of rain.

NOAA’s Atlas-14 rainfall probabilities for this area show that’s about a 5-year rain.

atlas 14 rainfall probabilities
NOAA’s Atlas-14 Rainfall Probability standards for the Lake Houston Area.

But rising floodwaters cut off large parts of Plum Grove – including escape routes. The new elevated City Hall nearly flooded again even though it’s far above the 100-year floodplain.

Local residents and city officials attribute their flooding woes to largely unmitigated development in nearby Colony Ridge. The City is currently suing the developer.

Flooding two weeks ago was so bad that the Plum Grove Volunteer Fire Department sealed off roads and warned people to stay out. Currents were reportedly moving fast enough to sweep cars off roads.

Photo from evening of 1/8/2022 courtesy of Plum Grove VFD after about six inches of rain.

As far as I can tell, 2004 Liberty County Subdivision Rules do not require “no adverse impact” for new developments. However, they do stipulate that “All roads and streets shall be designed to convey a 10-year storm event and not more than 6″ of water over the road in a 100-year storm event.”

Looks like the engineers missed all of those targets! This is a good example of why all jurisdictions should specify No Adverse Impact in their drainage regulations.

Posted by Bob Rehak on 1/20/22

1605 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.