Stormwater Tunnel on Buffalo Bayou Will Not Prevent Flooding
Plans Still Evolving
Comments and Questions
Please note that the Houston Chronicle has published a highly useful explanation of the coastal protection plan for Galveston Bay known as the Ike Dike. Unfortunately the paper has not figured out how to market to nonsubscribers.
Oct. 2, 2022
Large stormwater tunnels will likely not prevent flooding on Buffalo Bayou, according to the recent report from the Harris County Flood Control District.
Tunnels draining the federal flood control dams on upper Buffalo Bayou would not even be adequate to prevent a catastrophic overtopping of the dams or flooding of properties behind the reservoirs if a Harvey-like storm parked on top of the reservoirs, according to an engineering analysis prepared for Houston Stronger, a west Houston-based group formed in the wake of Harvey in 2017.
The Harris County Flood Control District is considering a $30 billion, 133-mile system of eight large-diameter stormwater tunnels to manage flood risk in the county. The district issued its Phase 2 feasibility report at the end of March and updated it in September. The district has been holding public meetings and taking public comments in preparation for the next phase of analysis to begin in the spring.
Limited Capacity
The probability that the proposed Buffalo Bayou tunnel would not prevent flooding downstream on the bayou is based on its limited capacity. The main tunnel would connect to two short 40-foot diameter tunnels, less than two miles long, draining Addicks and Barker dams far upstream. They would have a combined capacity of 11,600 cubic feet per second (cfs). This would drain into the much longer 40-foot diameter bayou tunnel which would have a capacity of only 12,240 cubic feet per second. Inlets or intakes draining the entire bayou downstream would have to be closed to accommodate stormwater flowing into the main tunnel from the two dams. The main tunnel would traverse the city deep underground for some 22 miles all the way to the ship channel east of downtown. (p. 127) (See also p. 1130)
That means that Buffalo Bayou would still flood because the bayou floods from urban rain runoff below the dams even when the dam floodgates are closed and no stormwater is draining out of the reservoirs. (See also here.)
Improving Flood Risk Knowledge. Proposing Solutions
A Draft Flood Plan for the Region
Key Finding: Lack of Information
Emphasis on Preparedness
How to Manage Development
Public Meeting in-person, Sept. 27, 5:30-7:30 pm. White Oak Conference Center, 7603 Antoine
Public Meeting virtual online, Sept. 29, 5:30-7:30 pm
Public Comment through Oct. 27
Public Comment through Sept. 30 on the Harris County Flood Control District’s proposal for county-wide stormwater tunnels
Sept. 26, 2022
Harris County does not have adequate information about where and how the county floods.
In fact, the entire watershed draining into the San Jacinto River does not have adequate information about flooding. This watershed includes Harris and parts or all of ten other counties from Galveston in the south to Huntsville in the north.
But the Harris County Flood Control District is working on it. (Back in 2017 the Army Corps of Engineers was going to work on it too and that work would have been done by now. But that project was changed.)
The lack of information is just one of the findings (p. 30) of a state-sponsored flood planning group which has been meeting and gathering information for nearly two years. The group of mostly citizen volunteers represent a variety of interests, including small business, agriculture, the environment, municipalities, water and electric utilities, the public, and more. Aided by public officials and the engineering firm Freese and Nichols, the group, known as the San Jacinto Regional Flood Planning Group or Region 6, recently released a massive draft report, which will be evaluated by the Texas Water Development Board, incorporated into a state flood plan, and sent to the state legislature in 2024 for possible funding. The state flood plan is to be updated every five years.
Managing Development. Being Prepared
The population of the San Jacinto region is expected to grow by one-third by 2050, and “one of the largest challenges” associated with this population increase, according to the report, is “determining how to manage development responsibly and continue to preserve the region’s natural resources.” (p. 24)
Increasing flood preparedness and improving flood management regulations and ordinances are also among the top priorities detailed in the report. (pp. 154 and 172)
The public can comment until Oct. 27 on the draft report, which is 302-pages long plus thousands of pages of appendices and maps and stuff. There are also two public meetings about the plan this week, one in-person Tuesday, Sept. 27, and the second virtual on Thursday, Sept. 29.
Big Bottom-Up Flood Planning Effort
The regional group is one of fifteen established by the state legislature in 2019. Based on the watersheds of the major rivers draining the state, the groups operate under the technical guidance of the Texas Water Development Board.
The purpose of the entire project is to “improve flood risk knowledge and propose solutions,” according to James Bronikowski, manager of regional flood planning for the state board. The ongoing effort is “intended to be a transparent process which relies on public input,” though based on the number of website responses and attendance at public meetings, public input appears to have been modest so far. (p. 295)
A Variety of Potential Flood Risk Reduction Actions, Nature-Based, Expanded Benefit
Of the fifteen watershed planning regions, San Jacinto is the second smallest region but the most densely populated, with twice the population density of any other region. Harris County has the most people at risk of major flooding. (p. 82) The 5,089-square mile region also includes some 3,173 square miles of farming, forestry, and ranch land, mostly forestry and ranching. (p. 56)
The draft report identifies 650 potential actions that could help reduce flood risk in the region. These are divided into three groups: 1. evaluations or studies, 2. strategies or plans, and 3. actual projects, both structural and non-structural, though sometimes the difference between strategies and projects is unclear. These “actions” are largely if not entirely existing projects planned by local municipalities, counties, or districts. The basis for assessing these actions included high need and existing risk to critical facilities, no adverse impact, quantifiable flood risk reduction, and regional benefit. (p. 32)
Incorporating nature-based practices in at least 90 percent of strategies and projects is a long-term (30-year) goal. (p. 30)
The report also expanded the traditional but controversial benefit-cost ratio, which tended to favor expensive properties. (p. 160) Projects and strategies can or should have other benefits like “public uplift, public education, low impact development features, and environmental benefits.” (p. 163)
Summer on the Bend
On Buffalo Bayou in Memorial Park
Plus Land Bridges For Publicity, Not Necessary For Wildlife
July 10, 2022
There was an occasional surprise smell of mushrooms on the dirt path through the tangled woods on this early morning. Crows laughed and gossiped in the treetops. Cardinals and wrens flirted back and forth high in the blue sky. Down low there was an annoyed hissing and rapid rustling and hustling away in the crispy fallen leaves.
It was summer and time for our seasonal photograph of the Bend in the River in Houston’s great Memorial Park. But Big Jim, our devoted photographer, naturalist, and conservationist, was not in town, so it fell to the assistant to take the shot. We’ve been documenting the same bend in Buffalo Bayou throughout the seasons for the past eight years.
The Memorial Park Conservancy, preoccupied with bulldozing trees, pouring concrete, and hanging name plates, does its best to block access to this wild and peaceful southeastern section of our beloved people’s Memorial Park, throwing up wire fencing, tree limbs, and warning signs. But the simple, narrow paths are well-trodden and maintained by anonymous volunteers. Someone has restored the wood handle on the rope swing used by the adventurous to fly across the lovely, shaded creek that drains the center of the park. Further downstream someone else has hung a small rubber swing on the bayou bank.
There is a long Houston tradition of swings over the bayou, of course, thanks to the strong, gracious trees that grow near the sloping banks. Historically this was a thrill mainly available to those privileged to grow up in upscale neighborhoods on one of the only local bayous that hadn’t been stripped of its trees and straightened in misguided and counterproductive flood control projects. But Memorial Park belongs to everyone, and for many years there was a knotted rope swing hanging from the great arm of the ancient Southern Magnolia that still stands on the bank even further downstream. The rope disappeared years ago, and the massive tree is looking somewhat haggard. One of the world’s oldest plants, there are few magnolias left in the wild. This Magnolia grandiflora could be 200 years old. Could have been there when the great landscape architect Frederick Law Olmsted passed through, noting the beauty and perfume of the magnolias on Buffalo Bayou. (p. 29)
Here’s a short video of the woods and the bayou taken from the bank, along with a glimpse of the sandy creek flowing nearby.
Deep Diving Into Flooding
Flood Control Looking at Countywide System of Flood Tunnels
System Could Be One of Largest in the World
- Tunnel Drains Would Take 10 Acres of Memorial Park, 14 in T. Hershey Park
- Buffalo Bayou Tunnel Longest, Most Expensive, Longest Time to Build
- Public Comment Encouraged Through Sept. 30
July 5, 2022
Updated July 6 with question about total acreage required for the tunnels.
It’s difficult to think about flooding during record heat and drought, when it’s too hot to go outside, the roads are melting and water lines are bursting. And when you do go outside your cell phone shuts down and burns up in your hand and the utility poles stink of toxic creosote and the shadeless, empty concrete parking lot radiates like a stovetop and scorches your face. And it’s not even the hottest time of the year yet.
But maybe there’s a way to think about all that and flooding at the same time.
The Harris County Flood Control District is thinking big. They are looking at digging a $30 billion, 133-mile system of 8 large underground tunnels to drain stormwater out of our bayous and streams anytime it rains enough to, say, push water levels over the ordinary high flow. The tunnels would also have the potential to collect rain runoff from neighborhoods and streets.
The scope of the project, the result of Phase 2 of the tunnel study, was announced during a public meeting in June. The details are contained in a $2.5 million report conducted for Flood Control by the global engineering firm Black and Veatch. It’s 1,860 pages, which is why it’s taken us so long to explain it. Sorry.
If built, the ambitious project might just be the largest stormwater tunnel system in the country, if not the world.
However, one can’t help but wonder about the environmental impact and unintended consequences of regularly siphoning flow from our streams, particularly in Buffalo Bayou. There are sediment (pp. 1836-1848), maintenance and water quality issues to explore. Mosquitoes. Muck. Ground faults, leaking oil tanks, wells, pipelines, bridge and building support structures underground, the impact and operation of the outfalls. (p. 191) Drought and shrinking, buckling soils. (p. 12) And what if a heating climate changes rainfall patterns?
The Houston Climate Impact Assessment predicts a hotter Houston climate (p. 48), longer and hotter summers (pp. 31-32) with little change in annual rainfall. (p. 37) However, extreme precipitation events are expected to increase (p. 42) as is the risk of drought. (p. 43) More rainfall all at once and less rainfall for longer periods. But where in the Houston region this extreme rain will fall is difficult to predict. (p. 47)
The Tunnel System
The benefits of a stormwater tunnel system, according to Flood Control, include using less total land compared to the district’s usual methods, presumably for achieving the same level of reduced flood risk. Total land use for the proposed tunnels is 34 acres, compared to 377 acres for “channel improvements,” 12,882 acres for stormwater detention basins, and 3,145 acres for buying out homes and properties in flood-prone areas, according to a presentation by Scott Elmer, assistant director of operations for Flood Control, during the public meeting last month.
Update: It’s unclear how Flood Control calculates the land use for the tunnels since the 10 shafts along the route of the Buffalo Bayou tunnel alone require over 76 acres of mostly wooded land, including wetlands. (p. 960)
Flood tunnels also would be faster to construct “than multiple traditional projects of equivalent combined benefit,” said Elmer.
Note that the land use comparison doesn’t include prairies, wetlands, forested parks or undeveloped greenspace, street trees, conversion of parking lots, rooftops, and lawns or other “sponge city” approaches with multiple co-benefits, in addition to reducing flooding, like reducing urban heating (which also attracts storms) and global warming, increasing healthiness, economic activity, and the attractiveness of our urban environment. Could be a worthwhile alternative investigation.
The 8 concrete tunnels would be 30-40 feet wide, some 80 to 180 feet underground (p. 1104) with 39-140 feet of earth covering the top of the tunnel. (p. 19) Between 8.2 and 24.5 miles long, they would be constructed starting shallow and getting deeper as they approach the point where they would discharge the stormwater. Most would discharge into (p. 70) Buffalo Bayou east of downtown, into the Houston ship channel below the turning basin, or, in the case of the Cypress Creek tunnel, into Spring Creek (p. 92). The Sims Bayou tunnel would empty into Sims Bayou near Milby Park. (p. 94)
Most would operate by gravity, though pumps would be required to pump out water between storms and prevent accumulation of sediment. (p. 69) Even though Houston is famously flat (excluding its many sloping ravines, gullies, and creeks), there is a 240-foot drop in elevation from the highest point (Hockley Mound in northwest Harris County) to Galveston Bay. (p. 37) Which is why our rivers and streams drain that way.
Though the Phase 2 report frequently refers to 4 tunnels selected for further study, Flood Control’s Elmer confirmed in an email that all 8 tunnel concepts, potentially benefiting 11 of the 23 watersheds in Harris County, are being investigated in the next phase of the process.
Tunnels could be located in these watersheds: Brays, Buffalo (including Addicks and Barker), Clear Creek, Berry and Vince; Greens, Halls and Hunting; Halls and Hunting; Little Cypress Creek-Cypress Creek, Sims, and White Oak. (p. 17) However, further study will be conducted during Phase 3, which is to start in Spring 2023. The Phase 3 study will be funded with $20 million from the 2018 Harris County flood bond program and is expected to take three years.
Bayou City Sitrep: What’s Been Happening
It’s All About Flooding
Open House public meetings, May 24, 26, and 31. Tell your flood stories to the San Jacinto Regional Flood Planning Group
List of committees, groups, studies, projects, etc., focused on regional flooding
May 10, 2022
Well, a lot has been happening in the past few months. And we’re talking about here in Houston. Though we haven’t been posting much, we have been attending numerous meetings, following developments, taking notes, and making comments.
The big topic is flooding, of course, and what to do about it. From the federal government on down through the state, region, county, and city, as well as local community and business groups, at every level there are projects, task forces, committees, and meetings about flooding in the Houston region.
The main issues are figuring out where flooding occurs (so far little focus on why), what to do about it, and how to spend public money to protect people (or structures?) in a fair and equitable way. Who needs flood protection the most? How to protect the most people? And what about critical structures like hospitals, fire stations or even grocery stores?
In the past the benefit/cost calculation for projects has been based on dollar values. In recent years there has been a general recognition that that’s not fair. A home is a home, no matter the appraised value.
So far the focus remains vaguely centered on “projects,” which would imply “engineering.” However, state (pp. 87-88) and county guidelines mandate the use of non-structural (including buyouts) and nature-based solutions. A recent federal flood assessment of the region also urged a greater reliance on green, nature-based, and small-scale solutions.
Nature-based methods are prioritized not only because they are the most beneficial and cost-effective. But also because nature moves. Storms change. Hard structures don’t. So spending billions on building and maintaining massive engineering projects like flood tunnels, ripping out trees and widening, deepening streams and bayous may not be the best investment. In fact, recent studies have shown that green infrastructure, which includes trees, parks, and green space, wetlands and prairies, adds value to property. (See here and here.)
Dams and Flood Tunnels
Some two years ago the Galveston District of the US Army Corps of Engineers released its Interim Buffalo Bayou and Tributaries Resiliency Study. This was in response to the massive flooding that occurred during Harvey in 2017 upstream and downstream of the federal dams on Buffalo Bayou in west Houston.
Almost a year later the Corps released its draft study of the entire regional watershed. Known as the Metropolitan Houston Regional Watershed Assessment, its main finding was that the metropolitan region needs a coordinating body “across all levels of government,” including highway, railroad, and utility agencies, to “set priorities” and plan for flood protection. (pp. 75-76)
It was not the first call for an overall coordinating body. And with the plethora of active committees and studies, it’s perhaps too soon to tell how much duplication of effort might be going on, what sort of coordination might occur, or how effective their plans might be.
Here is a list, current as of May 2022, of committees, groups, studies, projects, etc., focused on regional flooding and what to do about it. (See also our page of Rainfall, River Flow Gauges, Flood Maps, Tree Benefits, and Other Useful Links.)
Shocked Into Action
The initial Buffalo Bayou draft report shocked community groups into action. That first study rejected as too costly a massive flood tunnel to carry stormwater from the (normally dry) federal flood control reservoirs in the upper Buffalo Bayou watershed out towards the bay. The study also rejected, among other things, nature-based approaches to slowing and absorbing stormwater runoff before it enters our pipes and streams, as other cities are doing.
Interestingly, the Corps’ subsequent regional watershed assessment recommended holding rain where it falls, which is modern stormwater management. (See here, here, and here pp. 32-33 and here. And also here.) It also recommended a greater reliance on green and nature-based features, including pervious surfaces, and small-scale individual and neighborhood efforts to “reduce risk to downstream communities and broaden awareness of shared responsibility.” (p. 77)
So far we have seen little focus on these enlightened, cost-effective, and generally beneficial approaches during the many meetings we continue to attend and monitor. We’ve not yet even seen much focus on why different areas flood or whether current methods are working, though there are numerous ongoing attempts to figure out where flooding occurs, including efforts to reach out to the public.
Changing Course
Spring on the Bayou
April 7, 2022
Yes, it has happened. Spring has sprung. It seemed to take longer this year.
We were also late getting our spring shot of that bend in the bayou, the same high bank in the tangled woods of Houston’s Memorial Park we’ve been documenting throughout the seasons for the last eight years.
Our devoted photographer, Jim Olive, has high-tailed it to the California desert with his beloved in order to escape the unhealthy air here. Never mind that it is often too dangerously hot there even to walk outside.
So the assistant had to take over, enlisting an assistant-assistant. We braved the clouds of yellow tree pollen (“extremely heavy”) and only slightly impaired, fought our way into the woods through the wire and branch obstacles erected by the Memorial Park Conservancy.
Fortunately we made it down the well-traveled dusty path and out again before the start of the red flag warning of fire hazard and high winds. The sun was barely up over the trees.
It was a lovely day. We stood on the high bank, watching the muddy stream, listening to the birds singing to each other, wrens and cardinals. (Actual on-site recording) The flow was fairly high, over 1800 cubic feet per second (cfs), apparently mostly releasing from Addicks Reservoir in far west Houston. The gates on Barker were closed. (Here’s our page of links to rainfall and river flow gauges, flood maps, and other useful stuff.) Note that both federal reservoirs are public parks, used only for flood control, normally dry, their floodgates usually open.
The Trees Are Alright
Some of us have been concerned by the number of trees that seem to be slow to wake up. The world is confusing enough without having to go through super cold weather one day and sweltering temperatures the next. What to think?
Texas A&M urban forester Mickey Merritt is not concerned. He says that maybe we’ve just gotten used to trees leafing out earlier than they normally do. “The last couple of years have been pretty warm in February and trees leafed out early.” But we’ve had freezing weather more recently, and it’s been colder a little bit longer, he adds. Drought could play some role, but that will “really show up later when things get hotter.”
Oaks, he thinks, are ”right on time, live oaks especially.” Pecans “are always last – end of April, mid-May.” He’s not worried about sycamores either.
And it’s not unusual for a couple of the same species, red maples, for instance, in the same neighborhood, to leaf out one ahead of the other.
No studies have been done, but his observation, “just driving around,” is that he’s not seen “anything to make me concerned.”
SC
Just a Big Ole Alligator Gar
Seen in the Hogg Bird Sanctuary
Showing Off Buff Physique
Feb. 1, 2022
Bayou lover Katy E. was enjoying the sights and sounds in the woods of the Hogg Bird Sanctuary in Houston when she happened to look down at the remains of the tributary creek that once cut across what is now Westcott.
“At first I saw him head on and I thought it was an alligator,” she wrote in an email.
“This was what I first saw and I think you can see why I thought it might be an actual alligator,” she wrote of the above photo she bravely took.
“This guy was just drifting around,” she wrote. “He was pretty big.”
But it turned out to be an alligator gar, another of the ancient creatures, including alligators, alligator snapping turtles, and beavers, that inhabit our living bayou. The ancestors of the alligator gar in Texas date back over 200 million years. They can grow more than eight feet long and live over 60 years.
A Problem Nobody Wants to Fix
While Costly Fixes Wash Away
Update on Bayou Park Repairs and Damaging Stormwater Outfalls
Feb. 1, 2022
Recently we told you about the many drainage pipes jutting out from the banks of Buffalo Bayou and other streams that block the flow during storms. These pipes, or outfalls, violate city, county, and federal regulations by pointing directly across the channel. They act like dams, cause stormwater to back up, flood, erode, and take out banks and expensive sidewalks, leading to costly and continuous repairs.
The City of Houston is in charge of the pipes that collect this stormwater that rains down on the city. The Harris County Flood Control District is in charge of the channels and streams, both natural and artificial, that receive this runoff and send it out to the San Jacinto River and Galveston Bay.
But there were still questions hanging when we published the “illegal” outfalls report a couple of weeks ago. In 2020 the flood control district spent nearly $10 million in federal funds scraping, bulldozing and “repairing” the healthy green banks in Houston’s popular Buffalo Bayou Park between Shepherd and Sabine. The project was meant to repair damage caused by Harvey in 2017, three years earlier. Of course, by the time the bulldozers were revved up and deployed to the banks for the “repairs,” the bayou had naturally repaired and replanted its banks with deep-rooted, stabilizing native plants. Destroying these plants removed the natural network protecting the bank, causing at least one big tree to fall (as others have following Flood Control’s previous “natural stable channel design” work in the park).
One of the hanging questions from our previous report: why didn’t Flood Control fix the many stormwater pipes in the park blasting away like cannons pointed at the opposite bank?
Same Answer: Not Our Pipes
So Many Illegal Dams on Buffalo Bayou
How Big Pipes Block the Flow in Our Streams During Storms
Jan. 17, 2022
In a city full of engineers, surely they would get the engineering right.
But somehow the banks of our bayous and streams are punctured with stormwater drainage pipes that block the flow during storms. Pointing directly across the stream, they shoot a powerful force of rainwater runoff against high flow in the channel. This acts like a dam, stopping our streams from draining, causing water to back up as much as a quarter mile, according to witnesses. It also creates damaging turbulence and erosion and increases flooding.
It’s not like we don’t have a problem with flooding. Authorities are proposing multi-billion-dollar fixes to move more stormwater faster through the pipes and streams that collect rainwater from our roofs and streets and parking lots and send it out to Galveston Bay. These are big fixes like dredging, deepening, and widening 22 miles of Buffalo Bayou from the federal dams in west Houston to downtown. (p. 111) Or building a massive flood tunnel from the dams to the bay. (p. 106) (See also here and here.)
Seems like they might fix the problem drainage pipes first.
Violating City, County, and Federal Regulations
In fact, stormwater pipes (or outfalls) that point directly across the stream are a violation of City of Houston, Harris County Flood Control District, and even Corps of Engineers regulations.
Anything greater than a 60-degree angle to the bank is a violation of those regulations. (See Houston Public Works, Infrastructure Design Manual 2021, pp. 181, 183 and HCFCD Policy, Criteria, Procedure Manual, p. 230.) Actually, the federal requirements are even stricter. The Corps of Engineers requires the Harris County Flood Control District (and thus the City of Houston) to adhere to outfall angles no greater than 45 degrees to the bank. (Regional General Permit SWG-2009-00123, p. 3) The City of Austin, among other places, also requires an angle of 45 degrees or less. (See G.)
These regulations are at least twenty years old, if not older, according to representatives of Houston Public Works.
So how did we get all those stormwater outfalls blocking the flow in the bayous?
An Old Story
We’ve been pointing out this problem for some time. There’s the massive stormwater outfall in Memorial Park’s Old Archery Range, site of the public boat launch west of Loop 610. It was built in 2012-2013, designed by the engineering firm AECOM to point directly at the opposite bank, despite the outfall angle regulations.
Yes, We Have Alligators!
Right Here in the Bayou City!
Watch This Short Video of the Alligator
Jan. 9, 2022
So you’re walking or skating or biking along Buffalo Bayou in the park near downtown Houston, enjoying the balmy day, watching the people. You look down at the water and what’s that?! An alligator!
An alligator swimming right in front of everyone. In fact, this one is well known. Even has a nickname: Nacho, apparently named by canoe racing friends of SBB board member and river guide, Tom Helm.
Yes, we have alligators in Buffalo Bayou. They were here before we were. Some people might think that our alligators escaped from aquariums or something. Some people even think that Buffalo Bayou is an artificial ditch.
Nope. Buffalo Bayou is a river thousands of years old. Alligators are even older.
Alligators Been Here for Millions of Years
Alligators are a keystone species, meaning they create habitat and help sustain an ecosystem upon which other creatures depend. They’ve been around for millions of years. Amazingly, the bayou is crowded with very large, prehistoric creatures, though their habitat is increasingly diminished as Harris County Flood Control and property owners bulldoze and harden the banks with concrete and steel. (See also a proposal to engineer the natural banks in Memorial Park here.)
Besides alligators, there are massive alligator snapping turtles, alligator gar, and even beavers (long ago beavers were big as bears). (See also here.)
This relatively young, five-foot alligator was maybe looking for some turtles to eat, maybe even an alligator gar. Maybe just enjoying the sun.
A friend took this short video of the ‘gator swimming near Taft Street.
See for yourself.
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