Pushback Against Deeply Flawed Plans for Buffalo Bayou, Katy Prairie

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Oct. 22, 2020

Seems that nobody likes the Corps of Engineers’ draft proposal for killing Buffalo Bayou. Not even the coalition of developers, car dealers, concrete makers, contractors, homebuilders, realtors and others that was pushing hard for it.

But then the vague draft report has many parts. It’s an initial stage in a $6 million attempt to figure out a solution to the disastrous flooding in and around Buffalo Bayou and its tributaries connected to the federal flood control dams during Harvey in 2017. The report looks at a future of increased heavy storms and increased development surrounding the sinking, cracking dams built by the Corps in the bayou’s upper watershed more than seventy years ago. (p. 13)

Besides deepening and widening Buffalo Bayou to an apparently uniform width of three-quarters of a football field, the proposals include building a dam on Cypress Creek and a 22,000-acre reservoir behind it. (p. 18) During heavy rains the creek overflows south across the prairie into one of the federal dams that, during Harvey, could not contain all the stormwater running into it.

The Corps of Engineers proposes lining the banks and channel of Buffalo Bayou with articulated concrete block in “areas of high erosion.” Here’s how well articulated concrete block works in Buffalo Bayou. Photo January 2018

Building the dam on Cypress Creek would probably encourage development on land that now floods, leading to more flood problems, the Corps admits. Another major drawback acknowledged by the Corps: the project would significantly degrade more than two-thirds of the remaining Katy Prairie, which serves to hold and slow stormwater. (p. 176)

Nevertheless, the Corps’ draft report is leaning towards building the dam and deepening and widening Buffalo Bayou, laying back the ancient high banks for some 22 miles from the dams to downtown. This would be done to accommodate a flow of some 15,000 cubic feet per second (cfs).

The idea also is to buyout property downstream on Buffalo Bayou that was inundated by the opening of the floodgates on the federal dams during Harvey in 2017, as well as possibly property upstream that flooded because they didn’t open the floodgates.

Flood stage in Buffalo Bayou differs upstream and downstream as the bayou channel naturally widens as it winds downstream. From the dams for some six miles downstream to West Beltway 8, the Corps in the 1950s straightened and narrowed the bayou, effectively reducing its capacity. According to the National Weather Service, flooding begins in this area when the US Geological Service gauge goes over 8,000 cfs. For the USGS gauge downstream at Piney Point, flooding begins around 7,500 cfs. At the Shepherd gauge closer to downtown Houston, flood stage is around 18,000 cfs.

However, the Corps, which needs to keep the reservoirs empty in order to be able to capture runoff from the next storm, operates the dams on the basis that property downstream will begin to flood when the Piney Point gauge goes over 4,000 cfs.

Total estimated cost for the dam and bayou “improvement” is upwards of $4 billion. (Correction Oct. 24: upwards of $7 billion. p. 144)

According to Brian Harper, chief of the Galveston District’s planning branch, the Corps in its cost benefit analysis did not put a financial value on the loss of environmental benefits and functions of the bayou or the prairie, which include cleansing polluted urban and agricultural runoff, not to mention the growing local (p. 105) and worldwide problem of biodiversity loss.

Misunderestimating Buffalo Bayou

The Corps would also line the bayou channel bottom and banks with articulated concrete block in areas of “high erosion,” whatever that means. Never mind that concrete block does not actually work in Buffalo Bayou. The Corps’ Project Delivery Team (PDT), most of whom are from Corps offices in other parts of the country, does not seem to be aware that bank instability in our bayou is mostly from slumping, sliding down vertically. This happens no matter the steepness of the slope. Adding the weight of concrete block, which is designed for erosion caused by horizontal flow, only increases the likelihood of collapse, according to our experts and common sense.

And would it be piling on too much to point out that the report is so sloppy that its cover photo of a flooded Buffalo Bayou in Buffalo Bayou Park between Allen Parkway and Memorial Drive is misidentified as a flooded Interstate 10?

Read the rest of this post.

The Corps’s Interim Feasibility Report identifies this cover photo of a flooded Buffalo Bayou between Allen Parkway and Memorial Drive as a “completely submerged Interstate 10 outside Houston, Texas, on August 26th, 2017.”

4 thoughts on “Pushback Against Deeply Flawed Plans for Buffalo Bayou, Katy Prairie”

  1. Reggie Spiller says:

    Dear SBB,

    I am currently listening online to the proposal that the Corps has recommended and find that their findings are both reasonable and have merit. It appears that they are considering a combination of 3 different ideas: containment upstream, deepening of existing reservoirs and Buffalo Bayou Improvement. Personally I like the fundamental approach and analysis. Question…. what specific alternative would you suggest that would reduced the over all impact of flooding to the same level? I’d be interested in hearing from you. FYI… I live directly on the Bayou at the Gessner Bridge.

    Reg Spiller
    BIP HOA President

    1. Dear Mr. Spiller,

      Thank you for your email.

      I don’t believe that the Corps is recommending large-scale deepening or excavating the existing reservoirs. The draft report is long and seemingly contradictory in places but it does say that though they have ruled out excavating the reservoirs as an anchor measure, they are considering doing some spot excavation in places to create some extra detention within the reservoirs.

      The discussion about excavating the reservoirs is on pp. 134-136 of the Interim Report.

      Deepening and widening Buffalo Bayou is completely unfeasible, both from the practical and environmental point of view. The costs, both financial and ecological, would be enormous and ongoing, with very little benefit. The Corps itself points out that there would be no net benefit from this alternative.

      According to Google Earth, Buffalo Bayou at the Gessner Bridge is about 110 feet wide from top of the bank across. The Corps is proposing widening the top of the bayou channel to 230 feet. Here is an image of what that would look like. Note that this widening and deepening project would have to involve the replacement of numerous bridges and drainage outfalls and systems.

      Buffalo Bayou at S. Gessner Road

      The Katy Prairie Conservancy has done a major study and they are recommending nature-based alternatives. We would like to see more of what’s in their study.

      But our approach is to focus on stopping stormwaters before they flood our streams. Increasing conveyance only leads to the production of more runoff. Similar to building more highways. Flooding begins on the land. We think the focus should be on managing flooding in place, on property, in neighborhoods. And getting out of the way. That’s the modern approach to flood risk reduction.

      Stay in touch!

  2. Frank says:

    THANK YOU FOR STANDING UP

    I read the plan and strongly oppose scope downstream of the reservoirs. I live downstream of the Barker and Addicks reservoirs and willingly accept the risk of flooding during “800 year” storms for the benefits of living close to the Buffalo Bayou. For all of history, people have risked their homes and lives to live near nature (volcanoes, beaches, mountains, forests, rivers, lakes). The view comes with inherent risks. If you cannot handle the risk, select a different location.

    Is the USACE going to pay for my flood insurance premiums since they are “reducing” the flood risk? Nope. They are going to raise taxes AND raise premiums AND there is still the risk of flooding.

    I live near the Buffalo Bayou, was intentionally flooded by USACE after Harvey, and did not have flood insurance (above 500 year elevation). I have since rebuilt and carry flood insurance (since USACE can intentionally flood me whenever they deem it appropriate).

    The USACE needs to leave the Buffalo Bayou alone and let the people evaluate the risks. Harvey was a unique disaster and should not be a minimum standard for which cities are designed to handle.

    1. Thank you for your wise comment.

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