Tag Archive for: floodgates

Update on Floodgates, Dredging, Sand Traps from Martin, Costello

At Mayor Pro Tem Dave Martin’s final town hall meeting last night, he and Chief Recovery Officer Stephen Costello gave an update on the status of new, higher capacity floodgates for the Lake Houston Dam. Their talks also addressed dredging and sand traps.

City of Houston Chief Recovery Office Stephen Costello (l) and Mayor Pro Tem Dave Martin at Martin’s final town hall meeting on 10/17/2023. Term limits bar Martin from running again for Council, though he is running for City Controller.

According to the latest estimate, construction of the gates now looks like it could begin in mid-2026, barring unforeseen setbacks.

The City has scheduled more dredging for the San Jacinto West Fork south of where the mouth bar used to be. Also, Costello says the City has completed opening up ditches and tributaries north of the railroad bridge and is now starting on those south of it.

Finally, Costello revealed that Lake Houston has lost almost 20% of its capacity due to sedimentation. To receive future dredging grants, the City must take steps to reduce the rate of sediment inflow. Costello revealed plans for a pilot sand-trap project in a point bar outside the Hallett mine far upstream. He said that the mine had agreed to remove trapped sediment there for free. Otherwise, he did not explain why a possibly more effective location closer to the problem area was not chosen for the pilot project.

For more details on each, see below.

Gates Details/Timeline

The purpose of adding more floodgates to the Lake Houston Dam: to lower the lake faster in advance of a flood.

  • The City must now start to lower the lake so far in advance of a storm that storms can veer away before they arrive. This wastes water.
  • The existing gates have 1/15th of the release capacity of the gates on Lake Conroe. This makes a joint pre-release strategy virtually impossible in extreme storms.

After examining and discarding the notion of adding crest gates to the spillway portion of the dam, the City is now focusing on adding 11 tainter gates to the earthen portion of the dam (east of the existing gates).

Proposed location for 11 new tainter gates.

With Mayor Sylvester Turner’s help, the City secured enough funding for construction during the regular session of this year’s legislature.

Next steps include:

  • 3/24 – New environmental and historic preservation assessments, Army Corps permitting
  • 12/24 – Construction plans completed
  • 1/25 – Bidding
  • 6/25 – Award Contract
  • 5/26 – Begin Construction

The success of this plan will require the election of a new Mayor and City Council Representative who are committed to the project. Early voting begins next week.

Dredging Volumes, Costs

Dredging at various locations around Lake Houston will likely be a continuous effort for years to come. Sedimentation has already reduced the capacity of Lake Houston an estimated 18%. The City estimates future yearly losses in the range of 360-460 acre feet per year.

Historic and projected capacity loss in Lake Houston due to sedimentation.

One acre roughly equals the size of a football field. So imagine 400 football fields covered with sludge a foot deep. Each year!

To keep this problem in check, the City is already looking at doing additional dredging on the East and West Forks. It and the Army Corps finished major projects in both areas less than four years ago.

East of Atascocita and south of the convergence of the East and West Forks, the City plans to spend another $34 million to remove almost 900,000 cubic yards of sediment.

To date, Costello estimates that dredging nearly 4 million cubic yards of material has cost $186 million.

Summary of dredging costs and volumes in Lake Houston since Harvey

The City hopes to recoup some of these costs by reselling sand that it recovers from “hilltops” in the lake. Costello showed the heat map below. Notice the heavy sediment concentrations in the lake’s headwaters. This is because sediment drops out of suspension where rivers slow down as they meet standing bodies of water.

In addition to reducing the volume of Lake Houston, the sediment also poses a flood threat. It reduces conveyance of the rivers and lake forcing water up and out. Sediment blockages, such as the mouth bar, can also form dams that back water up.

Costello also addressed the ongoing dredging of 17 canals around Lake Houston. He said the focus is now shifting to the southern part of the lake.

Sand Traps to Reduce Inflow

In addition to dredging sediment from the lake, Costello also emphasized the need to reduce sediment coming downstream via sand traps. This last effort may be a condition of future grants for dredging.

Costello described two pilot types of pilot projects that the City is working on with the SJRA and sand-mining industry. The first is “sand traps” dug in point bars outside sand mines. The second: in-channel traps.

The idea behind the traps: dig holes in the river or its sand bars where migrating sand can settle out of the flow before it reaches the lake.

The first project may be near the Hallett Mine on the West Fork. According to Costello, the mine has agreed to remove the sand for free, thus reducing long term maintenance costs.

During Q&A after Costello’s presentation, however, he admitted that the City has no plans to try to get sand mines to reduce illegal emissions. In one notable instance, the TCEQ documented 56 million gallons of sludge discharged into the West Fork by the LMI mine.

Controlling sediment is crucial in reducing flooding. Accumulated sediment reduces storage capacity and conveyance for stormwater. The smaller capacity means lakes and rivers will flood faster and higher.

For high res versions of all the slides shown in the Town Hall, see this PDF.

Posted by Bob Rehak on 10/17/23

2241 Days since Hurricane Harvey

2023 Legislature Scorecard on Flood Issues: 2 Wins, 4 Losses, 1 Toss-up

The 2023 legislature scorecard, just five years after Hurricane Harvey, shows that flooding is fast becoming forgotten in Texas. Of the seven issues I tracked, the Lake Houston Area had two wins, four losses, and one that could be ruled a coin toss depending on your point of view.

In the Win Column

Let’s look at the good news first.

HB 1: More Floodgates for Lake Houston

Due to last minute heroics, HB 1 contained enough money earmarked for more gates to keep the project alive. A last minute phone-call campaign by hundreds of citizens making thousands of phone calls to key state legislators in the House and Senate succeeded in getting riders attached to the budget bill.

Few projects have inspired more hope among residents in the northeastern part of Harris County than the one to add more floodgates to the Lake Houston Dam. The Lake Houston Area Flood Task Force identified the project as one of the top priorities for the area.

The idea: to release water both earlier and faster in advance of major storms to create more storage in Lake Houston. Right now, Lake Conroe can release water 15 times faster than Lake Houston. And the release from Lake Conroe during Harvey was widely seen as one of the contributing factors to the flooding of so many homes and businesses in the Lake Houston Area.

The governor signed HB 1 on 6/18/23. It becomes effective on 9/1/23. With funding secured, Houston Mayor Pro Tem Dave Martin says final design on the gates is proceeding.

Lake Houston Gates Project
Lake Houston Gates Project
SB 1397: TCEQ Reforms

The TCEQ was under sunset review this year. No one proposed eliminating the TCEQ. But many people had ideas to improve it. They focused on two main areas: increasing transparency and improving enforcement.

The Sunset Commission recommended measures to improve public outreach, public notices, community input, and dissemination of public information, including the publication of best practices for sand mining.

The Commission also recommended updating the TCEQ’s enforcement practices to better focus on the riskiest actors and ensure staff treat potential violations consistently and based on severity. 

Breach in dike of Triple PG mine remained open for months, sending wastewater into Lake Houston. Texas Attorney General is now suing the mine.

The governor signed SB 1397 on 6/18/23. It becomes effective on 9/1/23.

In the Loss Column

SB 2431/HB 5338: Gulf Coast Resiliency District

These companion bills would have transformed the Harris County Flood Control District into the Gulf Coast Resiliency District. The new District would have been governed by a board appointed by the Governor instead of management hired by Harris County Commissioners.

The idea: to create regional solutions that benefitted all residents of Harris County, not just those that scored high on an equity formula.

The County fought the bill(s) tooth and nail. Each failed to get out of committee.

HB 1093: Financial Surety Guaranteeing Sand Mine Cleanup

The bill died in the House Natural Resources committee. It never even got a public hearing.

This bill would have required sand mining companies to post financial surety that would guarantee cleanup of mines before they were abandoned. Abandoned mines on both the San Jacinto East and West Forks are littered with the remains of once thriving operations. But when the sand played out, the miners walked away, leaving a legacy of blight for the public to clean up.

abandoned dredge
Abandoned dredge in mine on North Houston Ave. in Humble. Property is unfenced so kids can play on equipment.
HB5341: Lake Houston Dredging and Maintenance District

This bill also died in the House Natural Resources committee. House Bill 5341 would have created a Lake Houston Dredging and Maintenance District. Its purpose would be to remove sediment, debris, sand, and gravel  from Lake Houston and its tributaries to restore, maintain, and expand the Lake to mitigate storm flows. 

SB 1366: Flood Infrastructure Financing

This bill died in the Senate Finance committee. Senate Bill 1366 would have redirected surplus revenue from the economic stabilization fund to the Flood Infrastructure Fund. The State’s Flood Infrastructure Fund (FIF) has turned into one of the main sources of funding for Texas Water Development Board grants and one of the main ways that smaller counties and cities can fund flood projects. 

Passed but Failed
HB 1540: SJRA Reforms

HB 1540 passed. The bill implements reforms recommended by the Sunset Review Committee for the the San Jacinto River Authority. Many of those are good and needed reforms. They include provisions governing:

  • Gubernatorial designation of the presiding officer of SJRA’s board of directors;
  • Specific grounds for removal of a board member;
  • Board member training;
  • Separation of the board’s policy-making responsibilities and the staff’s managementresponsibilities;
  • Maintenance of complaint information; and
  • Public testimony at board meetings.

Approval should have been a rubber stamp. But at the last minute, Rep. Will Metcalf from Conroe offered an amendment that effectively fired Jace Houston, SJRA’s general manager and leader of the SJRA’s fight to reduce subsidence. The amended bill passed the Senate. Houston resigned effective 6/30/23. And now the Lone Star Groundwater Conservation District has no one to challenge unlimited groundwater pumping in Montgomery County.

Some in the Lake Houston Area who flooded during Harvey may rejoice at Houston’s departure. But differential subsidence is tilting Lake Houston upstream. It could make the Lake Houston Dam two feet higher relative to areas upstream near the county line. That could eliminate the safety margin above the floodplain for many homes in the next big flood.

subsidence in Harris County
Modeling shows 3 feet of subsidence near Harris/Montgomery county line, but only one foot at Lake Houston Dam.

As someone who had floodwater lapping at his foundation, I personally would put this one in the loss column.

The governor signed the bill on 6/18/23. It goes into effect on 9/1/2023.

Posted by Bob Rehak on 7/2/23

2133 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.

$750 Million Flood Plan Ignores Flood Risk, Public

Twenty-two months after learning it would receive $750 million from the US Dept. of Housing and Urban Development (HUD) and the Texas General Land Office (GLO) for Harvey Flood Mitigation, Harris County Commissioners finally approved a Method of Distribution (MOD) for the money on 3/14/23.

The MOD must be approved by the GLO and HUD before the county can begin spending the money. However, the plan virtually ignores flood risk and public comments.

What Happened to Flood-Risk Reduction?

The basic purpose of the HUD money, administered by GLO, is to reduce flood risk. The word “risk” appears 490 times in the MOD submission. Only one problem!

The proposed project scoring matrices never mention “risk,” at least not directly.

The plan contains one scoring matrix for Harris County Flood Control District (HCFCD) Projects and another for Partnership Projects.

HCFCD Projects

For the portion of the money going to the Harris County Flood-Control District, the MOD bases funding on:

  • LMI (Low-to-Moderate Income) Population Percentage (35 points)
  • Social Vulnerability (30 points)
  • Population (15 points)
  • Repetitive Flood Loss (20 points)

Unfortunately, giving weight to damages as opposed to risk, gives the same weight to areas that have already been mitigated as it does to areas that have not received a penny.

The MOD also says distribution of flood-control funds will be governed by the Equity Prioritization Framework (even though it doesn’t explain how). The 2022 version of that Framework gives 20% weight in scoring projects to “Existing Conditions.” Existing Conditions refer to the capacity of a channel to manage flood events of different intensities. But that’s as close as the MOD comes to addressing flood risk in project scoring.

Watersheds with a majority LMI population have roughly a billion dollars worth of uncompleted 2018 flood bond projects. With roughly a half billion of the $750 million going to HCFCD, the LMI and SVI requirements put on that portion of the money virtually guarantee that none will be left for more affluent watersheds.

So even though HUD and GLO rules allow 50% of the money to be spent in more affluent watersheds, the criteria adopted by Commissioner’s Court will likely preclude any of the money going there.

Partnership Projects

The portion of the money going to Partnership Projects has slightly different criteria. But that matrix also includes NO references to flood risk. It scores projects based on:

  • Project Readiness (20 points)
  • Percent LMI Population (25 points)
  • Project Efficiency (cost per person and building benefitted) (20 points)
  • Ancillary Benefits (environmental, economic, quality of life) (10 points)
  • Partner Contribution (25 points)

Nowhere did the plan provide direct comparisons of flood risk so that areas with the highest risk could be addressed first. Neither did the plan address flood severity. Thus, areas already mitigated that got one inch of flooding will rank as high as unmitigated areas that got 20 feet.

worst first
Chart showing feet above flood stage of 33 gages of misc. bayous in Harris County during Harvey.

Virtually No One Happy

The Harris County Community Resilience Flood Task Force submitted a letter strongly prioritizing flood-risk reduction. That got ignored as were most of the 235 pages of other public comments submitted.

Virtually no one seemed happy with the plan or the fairness of the distribution of money.

The county did not bother to respond directly to those who took the time to study the plan and submit comments. However, it did provide responses within the plan itself.

To paraphrase one of the generic responses: “Thank you for your comment. Here’s what we’re going to do. The GLO encourages regional and countywide investments in flood mitigation. But we’re prioritizing population in low income and socially vulnerable areas.”

Typical comment and response to proposed MOD. Name of commenter redacted.

Harris County has already spent $1.7 billion on flood mitigation since Harvey – the vast majority of it in LMI areas. There’s no hint of spreading the $750 million around to other areas.

Transparency Issues Also a Problem

The Harris County Community Services Department (CSD) will manage this money. But CSD has a serious transparency problem.

  • The transparency portion of its website hasn’t been updated in six months.
  • The MOD portion of the website hasn’t been updated for six weeks, even though much has changed since then.
  • Potential partners have complained about being in the dark.
  • Two weeks ago, the interim director promised to put out a call for partner projects. But the website still hasn’t announced the opportunities yet.
  • CSD still has not posted the plan approved by commissioners.

CSD’s lack of transparency was a major theme in the hundreds of pages of public comments.

What Next for Flood-Bond Projects in Outlying Areas?

With virtually all of the HUD money going to LMI areas, and with not enough money left in the flood bond to finish all the projects, Judge Lina Hidalgo and Commissioners Rodney Ellis and Adrian Garcia owe us an explanation. How do they intend to fulfill the County’s promise to voters who approved the 2018 Flood Bond thinking they would get something out of it?

Posted by Bob Rehak on 3/29/2023

2038 Days since Hurricane Harvey

Recommended Floodgates Could Release at Rate of Lake Conroe During Harvey

City of Houston Mayor Pro Tem Dave Martin’s office has supplied ReduceFlooding.com with the Black & Veatch Engineering report on the recommended alternative for adding floodgates to Lake Houston. One key finding immediately jumped out at me that wasn’t in Martin’s press release last week. The recommended gates would have a release capacity that virtually equals the highest release rate of Lake Conroe during Hurricane Harvey.

The Lake Conroe release rate during Harvey maxed out at 79,000 cubic feet per second (CFS).

The eleven tainter gates recommended by Black & Veatch would have a release rate of 78,700 CFS.

New Possibilities, More Certainty

That opens up a world of possibilities. For instance, the City could wait to start releasing water until it knew water was coming downstream from Harvey.

Said Martin, “Once constructed, we can release with a moments notice which gives us great opportunities to coordinate release protocols with the SJRA!!”

Previously, Public Works has been reluctant to release water in advance of a storm because the release rate of the existing gates is so small. They have to start lowering the lake so far in advance of storms that a storm can veer away before it gets here. If it does, that means water has been wasted.

The recommended floodgates should provide much more certainty for operators and avoid waste.

Key Elements of Recommendation

site of proposed gates for Lake Houston on east side of dam
Gates would be placed at the original channel for the San Jacinto River seen in foreground.

Other key elements of the recommendation include:

  • Locating the floodgates in the earthen eastern portion of the dam near the old channel of the San Jacinto River.
  • Creating baffles and a dissipation basin downstream from the new gates to break up the flow and reduce water velocity
  • “Outdenting” the gates (i.e., building them in front of the current dam)
  • A bridge between the two parts of the earthen dam
  • Using tainter gates, the same type used at Lake Conroe.
  • A 3.5 year construction schedule.

The last point means that if construction started in January, the earliest completion date would be mid-2026.

However, given the need to line up additional funding in the state legislature, 2027 is a more realistic date.

For a complete discussion of the project history, constraints, alternatives, recommended options, construction drawings, rationales, and costs, see the entire 28-page Black and Veatch Report by Chris Mueller, PhD, P.E.

Posted by Bob Rehak on 12/14/22 based on the Black & Veatch Report

1933 Days since Hurricane Harvey