Tag Archive for: coastal water authority

City of Houston Re-evaluating Benefit-Cost Ratio on Lake Houston Gates Project Alternatives

According to minutes of the Coastal Water Authority (CWA) February 9 board meeting posted in March, work on the project to add more gates to Lake Houston was paused in January while the City of Houston updated the project’s benefit-cost ratio.

gates for Lake Houston and Conroe
Lake Houston and Lake Conroe gates side by side. Lake Conroe’s gates (right) can release water 15 times faster.

CWA Board Minutes Give High-Level Overview of Concerns, Status

Screen capture from CWA Feb. 9, 2022, minutes approved and posted in March.

Earlier, in December, the board learned that the project team was trying to get the benefit/cost ratio above 1.0, so benefits exceed costs.

Screen capture from CWA January 12, 2022, board minutes.

At that time, the CWA hoped to receive the updated BCR later in January. But it still hadn’t happened by the February board meeting.

Martin Says “September-ish” for BCR Report

City of Houston Mayor Pro Tem Dave Martin said he hopes to have the BRC report in a “September-ish” time frame. I asked him whether the Community Impact report was accurate when it said the project had been scaled back to 500 feet of crest gates as opposed to the original 1500 feet. He said “no,” and that the engineers were looking at multiple options. He also said “1.0 is incorrect as well,” but did not elaborate.

That leaves a lot of questions regarding this project.

History of Project

After Harvey, the Lake Houston Area Task Force identified adding additional gates to Lake Houston as one of three primary strategies to reduce flood risk in the Lake Houston Area. The idea: to equalize the discharge rates of the flood gates on Lake Houston and Lake Conroe. Conroe’s is 15X greater. That makes it difficult lower both lakes quickly in advance of approaching storms.

As a temporary strategy, the City and SJRA agreed on a temporary, seasonal lake lowering strategy to create more capacity in Lake Conroe until more gates could be added to Lake Houston. But the strategy met with significant pushback from Lake Conroe residents and lawmakers. The Lake Conroe Association even took the SJRA to court to stop it.

At various times, City representatives have discussed 10 and 6 additional tainter gates, plus 1500-, 1200-, and 1000-feet of crest gates. Engineers and City officials have repeatedly emphasized the need to balance costs, downstream impacts, and flood risk reduction.

Back in October 2020, the engineers calculated that the upstream influence of the dam ended at approximately Lake Houston Parkway. But they never explained why. It would seem that if the influence extended upstream to US59 when the lake is at its normal level, that the influence should extend at least that far in a flood. However…

BCR Not Based on Harvey Damage

Much of the damage to the Humble/Kingwood Area during Harvey happened upstream of the West Lake Houston Parkway Bridge. It included:

  • $60 Million to Kingwood College
  • $70 million to Kingwood High School
  • $50 million to Kingwood County Club
  • 283 homes in Barrington
  • 218 homes in Kingwood Lakes
  • 97 apartments in Kingwood Lakes
  • 110 homes in Kings Forest
  • 100% of businesses in Kingwood Town Center
  • 225 homes in Kingwood Greens
  • 30 homes in Deer Cove
  • 3 Homes in Deer Ridge Estates
  • 32 homes in Trailwood Village
  • An unknown number of homes in Forest Cove
  • 78 townhomes in Forest Cove
  • All of the Big Box stores along 59
  • Homes and business north of Deerbrook mall
  • 40% of all businesses in the Lake Houston Chamber
  • Humble ISD admin building
  • Destruction of US59 southbound lanes
  • Union Pacific Railroad Bridge

However, Black & Veatch does not base its benefit-cost ratio calculations on another Harvey. They’re basing it on 25- and 100-year storms. Almost all homes, businesses and infrastructure near the lake are already above those levels – at least based on pre-Atlas 14 standards. That may explain the difficulty and delays with benefit/cost ratio calculations and the multitude of scenarios examined.

Time, Uncertainty: More Factors to Consider in Cost and Risk Reduction

Each flood-risk reduction alternative would reduce lake levels by a different amount during a 100-year storm and therefore require its own BCR.

Other factors to consider: How much time do dam operators really need to lower Lake Houston? And how much uncertainty are they willing to live with?

Given the desire to preserve water, these are crucial considerations. If forecasters can reliably predict a need to lower the lake two days before a storm instead of one, operators may only need half the number of new gates. That could get the cost down to the point where the benefit-cost ratio needs to be.

But don’t forget another element of uncertainty: Atlas 14. FEMA has not yet approved the new flood maps based on the higher rainfall totals. Those could put more people in or closer to the floodplains. Below is the timetable for flood map updates currently posted on the MAAPnext website.

Timetable for flood map updates from MAAPnext.

Posted by Bob Rehak on 4/4/22 and updated on 4/5/22 with MAAPnext timetable

1679 Days since Hurricane Harvey

May 2021 Gate Project Update for Lake Houston Dam

In its March 10th board meeting, the Coastal Water Authority (CWA) accepted the recommendation of a preliminary engineering report to add one thousand feet of crest gates to the uncontrolled spillway portion the Lake Houston Dam. The additional release capacity would let operators shed water faster before, during or after major storms to reduce the risk of flooding.

At the March meeting, directors also approved $4.4 million to begin Phase II of the project. Phase II calls for Black & Veatch to proceed to final engineering of the gates and a coffer dam to protect the work area during construction.

Read the minutes of the March board meeting here. The discussion of the gates starts on page 4 under Item B.

This morning, at its May board meeting, directors received an update on the progress of Phase II work to date and plans for the remainder of the project.

Start of Phase II Engineering Approved in March

In the March meeting, CWA approved funds to begin Phase 2 of the engineering which includes the final design of the selected alternative by Black & Veatch. The selected alternative was “crest gates” constructed on the uncontrolled spillway portion of the dam on its west side. (See below.)

Looking NE at the Spillway of the Lake Houston Dam is in foreground. One thousand feet (about a third) of this spillway will be replaced with crest gates. Gates will be placed at the end closest to the camera position in the image above.

Dam operators can raise or lower crest gates from a bottom hinge, much like the lid on a piano. When in the up position, gates hold water back. When lowered, they release water.

During Harvey, the peak flow over the spillway was five times the average flow over Niagra Falls. A wall of water 11 feet tall cascaded over the spillway above. Enough to fill NRG stadium in 3.5 minutes.

Scope of Phase II Design Work

Also in March, CWA and Black & Veatch completed negotiation of the scope and fee for the final design. The key deliverables during Phase II will include:

  • Plans to modify the spillway to support the 1,000 linear feet of crest gates (in five 200-foot long sections)
  • Design of the cofferdam system to protect the work areas during construction
  • Preparation of a new gate operations plan for CWA Lake Houston Dam operators.

Director Douglas Walker moved to authorize the Executive Director to issue a contract amendment with Black & Veatch Inc. in the amount of $4,465,727.00 for “Phase 2 – Final Design of the Lake Houston Dam Spillway Improvement Project.” Director Giti Zarinkelk seconded the motion. The Motion carried unanimously.

May Update

In the May board meeting this morning, directors received an update on Phase II work to date and plans.

In April, the design team held a number of workshops and coordination meetings.

Black & Veatch also completed three weeks of field surveying of the existing spillway; that’s why CWA temporarily lowered Lake Houston during that period.

In other news, for next steps CWA will:

  • Submit the permit application to the US Army Corps of Engineers by the end of May.
  • Support City of Houston in a public outreach meeting scheduled for June 17. The public outreach meeting will coincide with the public comment period for the permit application. CWA expects permitting to take nine months, i.e., through March of 2022.
  • Complete final design by the end of September 2022.
Screen capture from portion of CWA Board meeting today shows status of Phase II Design work on the dam.

Next Steps

Does all this mean construction is assured? No. The Army Corps could reject the permit or FEMA could find some fault with the plans. But at least it shows progress. If all plans and permits are approved, construction dollars have already been committed by FEMA. Originally, construction was supposed to have been completed within three years from April 8, 2020. That now looks unlikely unless the City can obtain a deadline extension from FEMA..

Posted by Bob Rehak on 5/12/2021

1352 Days after Hurricane Harvey

October 2020 Gate Update

On Friday, October 16, 2020, stakeholders in the Lake Houston Spillway Improvement Project met at the dam to review gate alternatives and progress on the project. The main item of interest: a review of options still under consideration to increase the outflow during major storms, such as Harvey.

History of Project

Shortly after Harvey, representatives from the Lake Houston Area identified “increasing outflow” as one of the main strategies to reduce flooding. Harris County Flood Control District even conducted a pilot study. Flood Control included $20 million for the project in the 2018 bond fund (CI-028). With matching funds identified, grants were then written.

FEMA approved the project. And in April of this year, the clock started ticking on the first of two phases.

Phase One Includes…

Phase One includes preliminary engineering and environmental permitting. It should take 18 months and is on schedule at this point. A key deliverable for phase one is verification of the benefit/cost ratio. But, of course, to determine that, you need to know the cost.

Alternatives Still Under Consideration

FEMA allotted 18 months for Phase 1. We’re six months into that. Work to date has focused on determining the optimal alternative. Five remain:

  1. Expanding the existing spillway by adding new tainter gates
  2. Adding a new gated spillway within the east embankment
  3. Creating a new uncontrolled spillway within the east embankment
  4. Building crest gates within the east embankment
  5. Developing crest gates within the existing spillway

Tainter gates lift up from a radial arm. The tainter gates on Lake Conroe have 15X more release capacity than the lift gates on Lake Houston.

Crest gates flop down from a bottom hinge.

Above: the current conditions at the Lake Houston Dam. Looking slightly upstream. East is on the right.

The east embankment is a solid earthen area 2800 feet long east of the spillway and existing gates. Water cannot get over it in a storm. By adding various structures in this area, engineers could widen the current spillway capacity, allowing release of more stormwater.

One main benefit: additional gates would reduce uncertainty associated with pre-releases. Operators could wait longer until they were certain an approaching storm would not veer away at the last minute. That would avoid wasting water.

Reverse angle. Note the difference in height between the east embankment (left) and the spillway (right). Looking downstream toward Galveston Bay.
Looking west toward Beltway 8. This shows the major segments of the dam.

Benefit/Cost Ratio Must Be > 1.0

The lake-level reduction benefits of these gate alternatives during major floods range up to roughly 8x. The costs also vary by roughly 4x. Those are order-of-magnitude, back-of-the-envelope estimates and far from final. Much hard work remains to develop tighter costs and tighter estimates of flood-level reductions. The latter will determine flood-prevention savings in a storm. And the benefits divided by the costs will determine the benefit/cost ratio.

In FEMA’s eyes, the benefit/cost ratio must exceed 1.0 to justify the project. Said another way, it must produce more benefits than it costs.

FEMA allotted 18 months for phase 1. We’re six months into that phase with a year left. Project partners expect results of the alternatives analysis before the end of the year.

Benefit/Cost Calculation

Given the ballpark costs of some of these gate alternatives, we will need very tight estimates of the benefits.

Potential Benefits include:
  • Upstream flood risk reduction
  • Reduced maintenance (debris management) for CWA
  • Improved Water Quality (post storm)
Potential Impacts include:
  • Increased scour and erosion potential to wetlands downstream
  • Increased water surface elevations to structures downstream
Calculating Benefits

Benefit Cost Ratio = (Net Present Value of Benefits)/(Project Costs)

Project Costs = (Capital costs) + (Net Present Value of Operations and Maintenance Costs)

Major Tasks Remaining in Phase 1

Barring surprises, the preliminary engineering report is due in February 2021 and environmental permitting should be complete by the Fall of 2021. Other tasks that must be completed by then include:

  • Hydrologic modeling of flows into and out of Lake Houston using the latest Atlas 14 data
  • Hydraulic modeling of Lake Houston, its Dam, and the San Jacinto River downstream of the dam to Galveston Bay
  • Calibration of models to historic storms
  • Examination of upstream benefits to residents/businesses removed from flood impacts
  • Examination of downstream impacts associated with additional flow release scenarios

It’s important to understand that not everyone who flooded in the Lake Houston Area did so because of the lake level. Some on the periphery of the flood flooded because water backed up in streams leading to the lake. If you got two feet of water in your living room, it doesn’t automatically mean a lake level reduction of two feet would eliminate your flooding by itself.

Congressman Dan Crenshaw (left) reviews the project with team members at the Lake Houston Dam and listens to their needs.

Phase 2 Still Not Certain

Assuming all goes well in the planning, accounting, and conceptual validation, FEMA will make a go/no go decision on construction at the end of next year or the beginning of the following year. Construction should take another 18 months.

Credits

Funding for this project comes from FEMA, Texas Division of Emergency Management, City of Houston and Harris County Flood Control. Other stakeholders include the Coastal Water Authority, Harris County, Fort Bend County, Baytown, Deer Park, and other communities adjacent to Lake Houston.

Posted by Bob Rehak on 10/17/2020

1145 Days since Hurricane Harvey and 394 since Imelda

Beta Downgraded to Tropical Depression

At 10 a.m. CDT, the National Hurricane Center (NHC) downgraded Tropical Storm Beta to a tropical depression. The NHC also cancelled the tropical storm and storm surge warnings that were in effect. However, flash flood warnings remain in effect for large parts of the seven-county Houston region, especially the southern part. A flash flood watch remains in effect for the entire region.

RadarScope split image. Left half shows track of active storms as of 9:06AM CDT. Right half shows total rainfall accumulation for Beta. Note band of extreme rainfall near Sugar Land and sharp drop-off near Kingwood.

Flash Flood Warnings and Watches

A flash flood warning means that flooding is in progress. A Flash Flood Watch means that conditions may develop that lead to Flash Flooding.

Source: National Weather Service. Updated at 10:29 a.m. 9/22/2020. Reddish area = Flash flood warning. Green = Flash flood watch.

Lake Conroe/Lake Houston Within Banks

Neither Lake Conroe, nor Lake Houston have yet been adversely affected by Beta.

The level of Lake Conroe stands at 199.63 feet. Normal conservation pool equals 201.

According to the Coastal Water Authority, Lake Houston is at:

Lake Level41.41 ft.
Normal Pool42.4 ft.
Source: Coastal Water Authority

USGS shows that even though the lake has received about 1.75 inches of rainfall to date…

…the lake level has been dropping, no doubt due to a preemptive release.

Posted by Bob Rehak at 10:50 on 9/22/2020 based on NHC, NWS, and RadarScope data

1120 Days since Hurricane Harvey and 369 since Imelda

Long-Term Lake Houston Dredging Plan in Development; West Fork Mouth-Bar 60 Percent Completed

In January, the City hired DRC Emergency Services, LLC (DRC) to begin mechanical dredging of the San Jacinto West Fork Mouth Bar. I’ve provided periodic updates on that. According to Houston Mayor Pro Tem Dave Martin, DRC has now officially completed 60% of that project.

In the meantime, other related dredging projects, including East Fork dredging and long-term Lake Houston maintenance dredging are reportedly taking shape. Here’s how pieces of the puzzle fit together. But one piece is still missing – long-term funding to pay for the maintenance dredging.

Two-Phase Program

DRC’s scope of work has two distinct phases:

  1. Phase One will remove accumulated materials near and at the mouth bar on the West Fork of the San Jacinto River.
  2. Phase Two will remove accumulated materials in the East Fork of the San Jacinto River AND other locations in Lake Houston.
West Fork Mouth Bar as of late June 2020.

During Phase One, 400,000 cubic yards of material will be removed over twelve months. To date, DRC has removed approximately 240,080 cubic yards of material. (See photo above.) That’s 60% in approximately 60% of the allotted time, so that part of the project is on schedule.

East Fork Mouth Bar as of May 2020. This areas went from 18 to 3 feet deep during Imelda, according to boater Josh Alberson. The above-water portion of this sand bar has grown three quarters of a mile since Harvey.

Phase Two of the project will consist of:

  • Hydrographic surveys of the West Fork of the San Jacinto River, the East Fork of the San Jacinto River, and Lake Houston to determine dredge material volumes
  • City of Houston advertising and awarding a dredging contract to the lowest responsive bidder

Phase Two will run simultaneously with Phase One to expedite dredging. 

Dave Martin, Houston Mayor Pro Tem

Mayor Pro Tem Martin did not provide an update on where Phase Two currently stands. But residents have reported seeing survey boats on Lake Houston, and the East and West Forks of the San Jacinto.

Mouth bar forming at Rogers Gully on Lake Houston. Example of kind of projects being considered for Phase 2. Photo late June, 2020.

Long-Term Dredging Plan in Development

Additionally, during Phase Two, City of Houston and its partners will develop a long-term dredging plan for Lake Houston. City of Houston or the Coastal Water Authority will execute the plan.

The intention: to fund dredging operations in perpetuity.

This phased approach will obligate the full grant funding before the 87th legislative session in 2021. This grant funding was made possible thanks to State Representative Dan Huberty (District 127) through the passage of Senate Bill 500.

Mayor Pro Tem Martin credits Huberty for his dedication to the long-term maintenance dredging activities on Lake Houston. “Representative Huberty has been a champion for his residents and a great ally in seeing these additional dredging efforts come to fruition,” said Martin.

$40 Million Project

The total project is valued at $40 million (except for the perpetuity part). Funding for the immediate dredging projects comes through a combination of:

  • City of Houston Harvey Disaster dollars provided by Governor Greg Abbott
  • Grant dollars from the Texas Water Development Board (TWDB)
  • Harris County Flood Control District (HCFCD) Bond Program.

Harris County Engineer, John Blount submitted the grant application for this project to the TWDB. But the City of Houston became a “subrecipient” and is now managing the project.

Long Term Funding – Still A Missing Piece of Puzzle

Lake Houston, a City of Houston asset, is losing capacity. Everyone has recognized that fact for decades. But as silt filled the rivers, inlets and lake, maintenance was deferred, reportedly for budgetary reasons. In 2017, during Harvey, the problem became so big that no one could ignore it anymore. Flooding was the immediate problem. But loss of water capacity is an even bigger, longer-term problem.

It’s one thing to have a long-term maintenance dredging plan and another to put it into action. But where will the money come from?

A tax on sand mines? Won’t work. Most aren’t in the City. Or even in Harris County.

Some have suggested creating a taxing district for lakefront homeowners. That won’t work either. Not enough of them. And it would create a stampede for the Oklahoma border. Moreover, it hardly seems fair; the lake is part of a City system that provides water to two million people and generates revenue.

The logical solution seems to be increasing the cost of water. Adding just a fraction of a penny per 1000 gallons should do it. Dredging isn’t just about reducing flooding. Or preserving views for lakefront homeowners. It helps preserve the lake’s capacity. And that benefits everyone.

As we develop a long-term dredging plan for the lake, we also need to consider a sustainable source of financing.

Posted by Bob Rehak on 8/12/2020 based, in part, on a release by Houston Mayor Pro Tem Dave Martin

1079 Days after Hurricane Harvey

NHC Gives 40-50% Chance of Tropical Cyclone Formation In Gulf This Week

NHC Special Tropical Weather Outlook NWS National Hurricane Center Miami FL 805 AM EDT Sun May 31 2020 For North Atlantic, Caribbean Sea and Gulf of Mexico:

Source: National Hurricane Center 5 Day Tropical Outlook for Atlantic as of 7:05AM CDT on 5/31/2020

The National Hurricane Center (NHC) forecasts the Eastern Pacific Tropical Storm Amanda, now centered inland over southeastern Guatemala, to weaken into a remnant low or dissipate over Guatemala or southeastern Mexico by tonight.

However, the NHC also predicts that the remnants of Amanda will move northwestward within a broader area of disturbed weather, possibly emerging over the southeastern Bay of Campeche on Monday.

If the remnants move back over water, environmental conditions appear conducive to support some redevelopment of the system while it moves little through the middle of this week.

Regardless of redevelopment, heavy rainfall is likely to continue over portions of southern Mexico during the next few days. For additional information on the rainfall threat, see products from your national meteorological service.

The next Special Tropical Weather Outlook will be by 3 PM EDT today, or earlier if necessary.

  • Formation chance through 48 hours…medium…40 percent.
  • Formation chance through 5 days…medium…50 percent.

 If it does become a named storm, it would be Cristobal.

Tropical Storm Amanda will likely cross into the Gulf of Mexico on Monday. (Source: NOAA via Space City Weather).

Too Early to Predict Direction of Storm

Jeff Lindner, Harris County Flood Control District meteorologist, says, “Where exactly any center forms will determine what sort of longer term track would be possible … across the Gulf of Mexico.”

“Regardless of development,” he continues, “a large plume of tropical moisture will be moving into the SW and eventually the western Gulf of Mexico this week. Some of this moisture will likely get directed toward the Texas coast by late week and next weekend.”

“As with any tropical system in this stage of potential development, there is lots of uncertainty.”

“The best course of action is to monitor weather forecasts daily and National Hurricane Center outlooks for any changes.”

Jeff Lindner, Harris County Flood Control meteorologist

Preparedness

Hurricane season starts tomorrow. The NHC predicts above-average activity this hurricane season.

Source: National Hurricane Center prediction on 5/21/2020.

Now would be a good time to prepare. The major risks in the Lake Houston area include river and street flooding (as we saw with Harvey, Allison and Imelda) and wind damage (as we saw with Ike). Ike led to prolonged power outages due to trees falling against power lines.

Make sure you have fresh batteries and a backup supply, as well as a weather radio.

Also make sure you have a way to charge your cell phone (vehicle or power block). And make sure you learn how to use the Harris County Flood Warning System to increase your situational awareness.

Familiarize yourself with the LINKS page of this website. It contains links to many useful sites specializing in preparedness and weather.

Remember: the COVID crisis presents an extra layer of complication this year.

Lake Level Report

As of this morning, the level of Lake Conroe was 200.23 feet and the SJRA continues releasing 1581 cubic feet per second. Their goal: to bring the lake down to 200 feet by tomorrow.

Also as of this morning, the Coastal Water Authority indicates that the level of Lake Houston is down approximately one foot.

Lake Level41.46 ft.
Normal Pool42.4 ft.
Source: Coastal Water Authority readings as of 7:30am 5/31/2020.

Posted by Bob Rehak on 5/31/2020

1006 Days after Hurricane Harvey

Lake Houston Property Owners Should Prepare for Lower Lake Levels (or Not)

Note: I posted this this morning before a surprise storm dumped up to 10 inches of rain on the Lake Houston Area this afternoon. Now the river is expected to flood … despite the pre-release. At 7PM on Tuesday, the floodgates on Lake Houston remain wide open. As the river rises past flood stage, any thoughts of being land locked are now moot.

Houston City Council Member Dave Martin issued a press release this morning warning Lake Houston property owners to prepare for lower lake levels. Houston Public Works and the Coastal Water Authority are monitoring forecasts calling for substantial rainfall over the next several days.

Lower Lake Levels Heading Lower

Lake Houston is currently at  42.11 feet and still receiving water from weekend storms. But that’s a half inch down in the last 12 hours.

Lake Houston has a normal pool elevation of 42.5 feet. All four gates on the existing dam structure are open and will remain open with a goal of lowering the lake to 41.5 feet before the next round of rainfall. Property owners are encouraged to secure property along the shoreline. 

Lake-Lowering Policy

Lake Houston is lowered if the National Weather Service predicts greater than 3 inches of rain within a 48-hour period. To monitor Lake Houston and the forecasted rain, click here. 

6-day precipitation forecast: 7 inches across the Houston Metro Area

Posted by Bob Rehak on 5/7/2019

616 Days since Hurricane Harvey

Seasonal Lowering of Lake Conroe Begins August 1

On August 1, the City of Houston Public Works Department, the San Jacinto River Authority (SJRA) and the Coastal Water Authority (CWA) plan to begin lowering the level of Lake Conroe as part of a joint operations plan to mitigate flooding threats during the peak of hurricane season. The plan calls for lowering Lake Conroe gradually through small releases – about an inch a day – until the lake level reaches 199 msl (mean feet above sea level).

Intent of gradual lowering of Lake Conroe is to avoid another 79,000 cubic-feet-per-second release rate as we experienced during Harvey. Until normal flow is restored to the West Fork, Lake Conroe will be lowered temporarily and seasonally to mitigate flood risk.

Lake Conroe to Be Lowered 2 Feet Through September

This initial lowering will last through the end of September to create additional storage in Lake Conroe which could delay releases and minimize release rates during a storm, thereby providing a buffer against flooding for residents who live downstream of the dam.

The next lowering would occur during the peak of the spring rainy season – from April 1 – May 31, 2019. However, that lowering would only be by a foot – to 200 msl, because the rain threat is usually lower in spring.

Only Until Dredging Restores River’s Flow

The joint operations plan calls for continuing to lower Lake Conroe seasonally in this manner while the U.S. Army Corps of Engineers dredges the West Fork of the San Jacinto to restore flow.

Hurricane Harvey deposited tremendous amounts of silt in the West Fork which  physically changed the river’s ability to safely pass water during storms. Hence, the dredging.

Phase-One Dredging Has Already Started

Phase one will go from River Grove Park to the West Lake Houston Parkway bridge. Great Lakes, the contractor hired by the Corps, has 269 more days to complete the initial phase.

Phase-Two Still Needs Funding

The total project could take longer. Community leaders are now working furiously to arrange funding to dredge the remainder of the west fork, including the mouth bar.

Mobilization and demobilization comprise 25 percent of the total phase one project costs (approximately $18 million out of almost $70 million). Having phase two ready to start before phase one ends could save that money, creating extra value for taxpayers and enabling even more dredging, say for instance, on the East Fork.

Temporary Lake Conroe Lowering Could Last Up to 3 Years

The City, SJRA, and CWA will continue the seasonal lowerings for up to three three years. They will monitor progress of the dredging and annually re-evaluate the need to lower Lake Conroe. If the river’s flow is restored before three years, the temporary lowering would cease.

Lakes will Operate under Two Different Strategies

LAKE CONROE
Lake Conroe is located upstream from Lake Houston. Large pre-releases immediately before a storm run the risk of pushing water into Lake Houston at a rate that could flood residents. Therefore, the SJRA will release at a much more gradual, controlled rate and maintain the lower level until the largest flood threat passes.

LAKE HOUSTON
Lake Houston, as the lowest lake on the river system, can pre-release more safely. Therefore CWA will pre-release from Lake Houston if the National Weather Service predicts more than 3 inches of rain within the San Jacinto River basin in a 48-hour period. Coastal Water Authority will lower Lake Houston to 41.5 feet from its normal elevation of 42.5 feet.

To track lake levels visit:

  • Lake Conroe – www.sjra.net
  • Lake Houston – www.coastalwaterauthority.org

4 Million People Depend on City for Water

Lake Conroe and Lake Houston comprise two of the largest parts of the City’s drinking water system. More than 4 million Houstonians and residents of the greater Houston region rely on water provided by the City.

Posted by Bob Rehak on July 30, 2018

335 Days since Hurricane Harvey

Need for Sediment Management Planning

Sand and sediment clog our rivers and lake. “Dredge!” you say.

“Not that simple,” say the experts. “Who will pay for it? How much should we dredge? Where will the sediment go?”

That’s why we need planning for sediment management. We need to dredge the worst parts of the river now; the U.S. Army Corps of Engineers (USACE) has already started that as an emergency project. But we also need to dredge other parts of the river that are not quite critical yet. And we need to figure out how to do all this on a regular basis so that it never gets this bad again.

A giant sand dune has formed at the mouth of the west fork of the San Jacinto. It is not being addressed by the Army Corps dredging project but should be. Thousands of homes upstream from this massive blockage flooded during Harvey.

Sediment Management Challenges That Lie Ahead

I have talked about these issues with experts from Harris County Flood Control and USACE. Both say planning is crucial to a successful maintenance dredging/sediment management program. One provided this document: Galveston-Bay-Programmatic-RSM-Plan-Rev-1, as an example of what we need for the San Jacinto. It’s a long document – 112 pages. But it is worth reading the executive summary, introduction and table of contents at the very least. Parts of it discuss the upper reaches of the San Jacinto. But the main value it provides is that it outlines the challenges ahead.

  •  Who will lead the effort? Who will support it?
  • How much money is needed per year? How can we budget for it? Who will share in the costs?
  • Where will the dredged materials go? How can we identify opportunities to reuse and sell them? Who will market them and how? To what extent can sales defray dredging costs?
  • What are the true life-cycle costs of the sand and sediment that miners send downstream to us?
  • How can we reduce their contribution to the problem? Is there a way to make them part of the solution?
  • How can we coordinate upstream and downstream efforts so that the entire river system flows freely?
  • How can we remove channel blockages more quickly after floods to help prevent additional flooding?

All of these are difficult questions. Starting such an extensive program is like starting a new business.

Budgeting Comes First

A business plan and budgeting are the first issues we need to address. Where will the money for all this come from? Without answering that first, everything else is moot.

So who are the stakeholders?

  • City of Houston – Ensuring the future of Lake Houston is essential to ensuring the future of the City. It’s the City’s main source of water.
  • Harris County Flood Control – Half of the people that live in the county, live in the City.
  • San Jacinto River Authority (SJRA) – The State created the Authority back in the 1930s to impound water and protect people from flooding. Those missions were recently reconfirmed by the Governor.
  • Coastal Water Authority – CWA is the contract operator for Lake Houston Dam and Reservoir. They sell water just like SJRA and can raise money thru water rates to fund flood mitigation. Their enabling legislation mentions drainage and flood responsibilities – same as SJRA.
  • State of Texas – This region has a quarter of all the people who live in the state. Nuff said.

Expecting all costs to be covered by the Harris County Flood Bond in perpetuity is just wishful and foolish thinking. The bond is for capital projects, not ongoing maintenance. You might be able to justify the first dredging as “channel improvements.” But after that, for the sake of the community, we need to find a way to make this program sustainable. Paying interest for ongoing operations is unwise.

Cost Sharing and 5-Year Intervals Can Make It More Doable than Avoidable

In 2000 Brown & Root, recommended dredging every 5 years – a perfect match for a venture with five partners. If each budgeted one fifth of the cost annually, and you did only one fifth of the job each year, this just might be more doable than avoidable. (Avoidance seems to have been the preferred approach in the past.)

We can’t budget sediment management forever on an emergency basis. That’s like using an emergency room for basic medical care. It’s probably not the best idea, nor the most cost effective. So let’s begin the dialog with stakeholders. As Grandma used to say, “An ounce of prevention…”

Posted on July 13, 2018 by Bob Rehak

318 Days since Hurricane Harvey