floodplain maps Archives - Reduce Flooding

New Floodplain Maps Remain Secret For Now – At Least in Harris County

11/14/25 – Both Harris County Commissioners Court and the San Jacinto Regional Flood Planning Group agreed yesterday to keep new, updated Harris County floodplain maps secret from the public. They accepted Harris County Flood Control District’s (HCFCD) explanation that they couldn’t release the maps until FEMA finished vetting them…a process that has gone years longer than scheduled and could drag on for years more. Neither group:

Asked for an explanation of what was taking FEMA so long
Asked how withholding the maps could negatively impact Harris County residents
Pointed to any FEMA regulations requiring that FEMA must release information first
Agreed to pressure FEMA to speed up the vetting process
Addressed why local authorities elsewhere are releasing updated maps before FEMA.

However, a spokesperson for HCFCD insisted after the meetings that HCFCD had a contract with FEMA that prohibited HCFCD from releasing maps paid for with taxpayer money. However, she could not immediately produce the contract for this post.

Other Areas in Texas Released Updated Maps Ahead of FEMA

Other authorities elsewhere seem to have no trouble releasing their updated maps based on Atlas 14. Take the San Antonio River Authority (SARA), for instance. They have posted a DRAFT floodplain viewer since 2022 with disclaimers, even though FEMA has not yet released its versions of the maps.

*Screen capture on 11/14/25*. *Site also contains disclaimer.*

The SARA maps even show the 30-year chance-of-flooding to help mortgage applicants understand their flood risk.

*San Antonio River Authority Draft Floodplain Viewer showing 30-year flood risk.*

Williamson County (Georgetown/Round Rock) also has released its Atlas-14-based floodplain maps ahead of FEMA. The maps feature a slider that lets you compare the extent of old and new floodplains.

*11/14/25 Screen capture of old/new floodplain comparison in Williamson County’s draft viewer.*

So, it is possible to release new maps ahead of FEMA. No regulations that I can find prohibit it. If Harris County’s contract prohibits it, I will do a followup post when HCFCD produces the contract.

San Jacinto River Flood Planning Group Decides Not to Press Map Update Issue

The San Jacinto River Flood Planning Group (RFPG) met yesterday. Among other things, they voted on a progress report for the Texas Water Development Board that showed their work to date on the next iteration of the state flood plan.

Their interim report identified floodplain expansion everywhere in the river basin except Harris County.

That’s because maps for Harris County were redacted at the request of HCFCD. And that generated a lot of discussion.

One member of the committee said, “We have omitted mapping within Harris County as part of this tech memo deliverable, since that’s posted to the public.” [Emphasis added.] That same member later added, “Not incorporating that maybe oversimplifies or otherwise misleads the general audience.” That member proposed updating the maps before submitting the report to TWDB.

However, instead, the committee decided to simply edit text to remove FEMA’s delivery date for the new maps which HCFCD claims FEMA has repeatedly missed.

“It’s not a change to technical content or substantive content, it’s just going to be how it narrates,” another member said.

The committee also discussed applying political pressure on FEMA to release the maps, but decided not to.

Harris County Commissioners Court Takes No Action on Map Updates

Harris County Commissioners Court on 11/13/25 also included a discussion of the status of flood map updates. (See Item 325 on the agenda.)

Commissioner Tom Ramsey kicked off the discussion by saying, “We have known that FEMA is going to, at some point, issue new floodplain maps for Harris County. And we sit here waiting for FEMA to release these.” Later, he said there would be a significant difference in the extent of floodplains. “The existing 500-year floodplain is now going to be the 100.”

Commissioner Adrian Garcia then said, “This is not my first rodeo related to maps.” He continued. “It’s going to be tough enough when FEMA releases the maps on us, because…

“We’re going to find … developers holding properties that now are going to potentially be un-developable.”
Precinct 2 Commissioner Adrian Garcia

Garcia suggested that perhaps the National Association of Counties (NACo) “move this item along because it is in limbo.” Then he added, “The federal government needs to own this. They need to do their part. And then we can work it at the local level.”

Tina Petersen, executive director of HCFCD claimed, “The responsibilities of FEMA have always been clear. They are responsible for releasing the flood insurance rate maps.” While that’s a true statement, FEMA is moving away from basing NFIP insurance rates strictly on flood zones. However, the maps will remain critical for mandatory flood-insurance purchase requirements for federally backed mortgages.

Commissioner Rodney Ellis tried to pin Petersen down by asking if other places were releasing updated flood maps and adding disclaimers like “draft” or “preliminary.”

Petersen dodged the question. Her 55-second response boiled down to, “We believe we are close. We believe it is prudent to wait.”

Petersen also dodged Ellis questions relating to FOIA requests and how much the new maps cost the county.

Commissioner Leslie Briones asked for an update on what FEMA has accomplished in the second half of the year. Petersen replied, “Really, where FEMA is at now is all of the data that has been submitted from the flood control district has been reviewed, and they are currently working to develop the draft flood insurance rate maps.”

Briones concluded the discussion. “We are all in and making sure we’re supporting you so that we can get the information out and work in support as strongly as possible,” she said.

That concluded the discussion. Commissioners took no action. They just moved to the next agenda item.

No Good Answers

In the end, the recognition of higher flood risk could increase flood insurance premiums and make floodplain properties more difficult to develop.

Kicking the can down the road and pointing fingers at FEMA, an agency undergoing radical change, avoids difficult conversations now. But it also exposes Harris County residents to higher flood risk.

See the Harris County Commissioners Court discussion of flood maps at 3:13:36 of this video. The San Jacinto River Flood Planning Group does not publish video of its meetings.

FEMA’s Region 6 Map Division would not confirm when they will release new flood maps for Harris County. They referred me back to HCFCD.

HCFCD has refused to share flood risk information with the County’s own Community Flood Resilience Task Force despite repeated requests since 2021.

And partially as a result, people are building and buying tens of thousands of homes in Harris County floodplains that could flood in the next big storm.

Posted by Bob Rehak on 11/14/25

2999 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.

Floodplain Maps for 5,316 Acres West of Kingwood Contradict Developer’s Claim

11/4/2025 – FEMA floodplain maps contradict a claim made by Scarborough Development/San Jacinto Preserve in a presentation made to the City of Houston and Harris County officials on 10/29/25.

The developer recently bought 5,316 acres, mostly in the floodplains and floodways of Spring and Cypress Creeks, and the San Jacinto West Fork. The land lies in both Montgomery County and the City of Houston’s extra territorial jurisdiction. The developer also wants to build a bridge into Harris County.

In documents obtained from the City of Houston, the developer claimed it would only be “developing land at or above the Atlas 14 100-year floodplain.” See copy in red box below.

*Presented by developer to City of Houston and Harris County on 10/29/25*.

However, superimposing their development plan on FEMA’s current floodplain maps developed before Atlas 14 contradicts that claim. Why?

The extent of proposed development matches the limits of pre-, not post-, Atlas 14 100-year floodplains.

Net: developing in this area is more dangerous than it may look. 500-year floodplains could soon become 100-year floodplains.

For more detail, see the discussion of Atlas-14’s history and the sequence of maps below.

A Brief History of Atlas 14

FEMA’s current floodplain maps for this area date to 2014, four years BEFORE the start of Atlas 14 in Texas. And to my knowledge, FEMA has not yet released new flood maps based on Atlas 14 for this region.

*From FEMA floodplain map of Scarborough/SJP property*. *Effective date: 8/18/2014.* *Screen captured today.*

NOAA began updating rainfall precipitation frequency estimates in 2004; they called the effort “Atlas 14.” But NOAA didn’t update Texas statistics until 2018. Such rainfall estimates form the basis for flood maps.

In Montgomery County (MoCo), pre/post estimates for the standard 100-year/24-hour rainfall varied by more than a third. MoCo adopted Atlas 14 values of ~16.1 inches for the 24-hr, 1% storm (at Conroe), up from the previous standard of ~12 inches. That’s an increase of 4.1 inches or 34%.

Just as important, until earlier this year, MoCo drainage regulations often let developers avoid building stormwater detention basins that would offset that additional rainfall.

Also consider that Montgomery County has been one of the fastest growing counties in the region and in America. Its population has grown by almost a third (31%) since 2018. That population growth comes with a growth of impervious cover (roofs, driveways, streets, parking lots, etc.) that doesn’t soak up rainfall.

I’m not aware of any recent studies that show the cumulative impact of additional rainfall and impervious cover together with a deficit of detention.

Given those issues, common sense says flood elevations would increase. And in fact, preliminary guidance from Harris County indicates that floodplains will expand by 50% to 100% when FEMA releases updated flood maps based on Atlas 14.

New Plans Show Development Extending to Old 100-Year Floodplain

When I first saw the developer’s new plans, the plans didn’t seem to match the claim that they would only develop land “at or above the Atlas 14 100-year floodplain.” That made me suspicious. So, I performed an experiment.

I superimposed the developer’s plans over FEMA’s current (pre-Atlas 14) map dated 2014. I then varied the opacity of the layers in Adobe Photoshop so I could see how the two matched up. Long story short, they matched perfectly. See the sequence of images below.

*Layer 1: From FEMA’s Flood Hazard Layer Viewer. Scarborough property is in center between Spring Creek (diagonal) and West Fork (right).* *Brown areas = 500-year floodplain. Aqua = 100-year. Striped = floodway.*

Next, I superimposed the development plan that Scarborough presented to City of Houston and Harris County.

*Layer 2: Gray areas with waffle pattern represent claimed “net developable area.”* *Red = property boundary.*

Then, I varied the opacity of the development plan until you could see the floodplains behind it.

*Composite with partial transparency of overlay*

Enlargement clearly shows that development stops at the old, pre-Atlas-14, 100-year floodplain.

*White lines from 2014 FEMA map form boundary between 100- and 500-year floodplains. And waffle patterns from developer’s plans stop at white lines.*

New maps reflecting higher rainfall rates and more impervious cover will likely show those white lines cutting well into the brown so-called developable areas, if not eliminating some altogether.

Where Did Developer’s Claim Come From?

So, where did the developer’s Atlas 14 claim come from? I have talked to three people who were in the meeting. Not one could tell me with certainty. They all expressed reservations and doubts about it.

I have also reached out to Scarborough several times to understand their position, but they have yet to return phone calls or emails.

So, I’m going to remain skeptical until I see proof of their claim and FEMA’s new Atlas 14 maps. FEMA may release them in 2026. But the proposed maps will then go through public comment and revision cycles. That could mean they won’t become official for at least another three years.

Make This An Election Issue

In my opinion, the best use for this property would be to turn it into a state park. That would help protect areas both up and downstream. With an election coming up next year, our representatives will have their ears to the ground. The time to start a letter-writing campaign is now. Contact all candidates.

Turn this into an election issue.

Make sure we elect someone who is more interested in protecting public safety than private profits.

Posted by Bob Rehak on 11/4/25

2989 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.

Three Ways to Find Out If You Are In a Floodplain

Here are three quick and easy ways to find out if you are in a mapped floodplain of any kind.

FEMA – National Scope

The first site is FEMA’s National Flood Hazard Layer Viewer. Using this site, you can check any piece of property in the country…including Pike’s Peak or Walden Pond…just in case you want to do a Thoreau.

Another benefit of the FEMA site is that it spans county boundaries, i.e., if you live on the Harris/Montgomery County Line.

FEMA’s National Flood Hazard Layer Viewer can track creeks, etc. across county lines. Please note the big green space in the center of the frame. This is the new Perry Homes development, Woodridge Forest. Neither the FEMA map, nor the MoCo map below contain flood zone information for this area although much of it was wetlands before Perry clear cut it.

Harris County

Harris County operates a site called “Flood Education Mapping Tool.” The Harris County site superimposes drainage ditches, streams, creeks, bayous and rivers and even gives you their names and numbers. Very helpful if you want to report a problem some day, or track up or downstream to see where drainage issues may be originating.

Montgomery County

Montgomery County operates a site called “Am I in a Floodplain?” It includes some very helpful interactive tools, topographic maps and more.

*People on Killerbee Lane will be pleased to know that they are not in any mapped floodplain.*

Benefits of County Sites

According to Diane Cooper, a hydrologist with more than 20 years of experience in forecasting floods, both of the County sites have better imagery and more layers than the FEMA site.

Layers comprise one of the key features of both county sites. Experiment with them. I’m especially fond of the background layers.

They let you see the flood zones superimposed over simple maps, satellite images, historical satellite images, and more. The Montgomery County site even lets you click on streets and information about them pops up. I learned, for instance, that one subdivision in MoCo has a street named Paper Wasp Lane. You really don’t want to mess with the people on that street! It’s not far from Killerbee Lane. Let’s get up a football game between those two streets! I’d pay to see that.

Posted by Bob Rehak on October 10, 2019, with help from Diane Cooper

771 Days since Hurricane Harvey and 20 since Imelda

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