Tag Archive for: gages

San Jacinto Master Drainage Plan Uses Gage UPSTREAM from Sand Mines to Estimate West Fork Sedimentation

Appendix F of the San Jacinto River Basin Master Drainage Plan discusses the sediment contribution to Lake Houston of various tributaries. It asserts that Cypress Creek, Spring Creek, and West Fork sub-watersheds are the highest contributors of suspended sediment to Lake Houston, contributing an estimated 38.7 percent, 26.8 percent, and 13.0 percent of the total sediment load, respectively.

However, to measure sediment on the West Fork, the study team used a gage at I-45 – UPSTREAM from virtually all West Fork sand mines. This explains a huge disparity between measured data and visual observations. But the report never even acknowledges the visual observations.

I have previously posted about the 3600-page master plan. In many respects, it is a masterpiece that contains good and valuable information that will help mitigate flooding throughout the watershed. The comments in this post relate ONLY to Appendix F on sedimentation, which in my opinion contains a serious flaw.

Misleading Impressions

The problem with using the gage at I-45: it rules out certain contributions to sedimentation that the report barely acknowledges.

Cypress Creek and Spring Creek combine before merging with the West Fork. Thus, you would expect five times more sediment coming from Spring and Cypress Creeks than the West Fork, based on their findings. Yet almost every time I photograph the confluence of the West Fork and Spring Creek, I see more sediment coming from the West Fork, despite the fact that Lake Conroe blocks sediment coming from the upper part of the watershed. See below.

Confluence of Spring Creek and West Fork San Jacinto. Each shot taken in a different month and from a different angle. But the siltier stream in each case is the West Fork where virtually all the sand mines are.

Location of West Fork Gage Never Fully Specified in Report

The West Fork gage number is listed on page 114 of Appendix F. But the description says only, “W Fk San Jacinto Rv nr Conroe Tx, Gage #08068000.” At another point (page 115), it lists the gage near Lake Conroe. To find the exact location of the gage, one must go outside the report to a USGS site. Then to see where the gage sits relative to West Fork sand mines, one must back up to page 61 of Appendix F. Most readers will just assume, given the scientific nature of the report, that the authors used a gage at a representative location, not one that ruled out sediment from sand mines.

Even a careful reader of the report could conclude that the contribution of sand mines to sedimentation is minor in the grand scheme of things. TACA would welcome such a conclusion.

The report ignored thousands of photos posted on ReduceFlooding.com as well as TCEQ reports citing sand mines for non-compliance.

The implications of measuring sediment upstream from sand mines, overlooking visual evidence, and ignoring official reports calls into question some of the report’s recommendations. For instance, #2 suggests using “existing [emphasis added] stream gage data” … to “inform where higher suspended sediment is originating within each sub-watershed.”

Sorry, you can’t get there from I-45. And if sand mines are an issue, neither can you get there from LIDAR surveys taken every several years, which the report also recommends. Sand mine discharges happen frequently and sporadically, often under the cover of darkness.

Sand Mining Not Seriously Considered as Possible Source of Sedimentation

The report, for the most part, blames sedimentation on new development and stream bank erosion. It does not consider:

Intentional pumping over dikes
Pipes buried under dikes
Breaches and pumping into surrounding wetlands that drain into the West Fork
Breaches in abandoned mines
Breaches into drainage channels just a few yards upstream from the West Fork
Intentional breaches. Note the backhoe tracks and sharp edges to the breach in this video.

Sedimentation Report Needs More Gages

You can’t document the volume of such breaches and illegal pumping from a helicopter. However, you can’t overlook such practices either.

What we really need is a sediment gage downstream from the sand mines just before the West Fork joins Spring Creek. A gage at that location would go a long way toward calculating the volume of sediment escaping from sand mines.

Report Also Needs Revision Before Legislative Committees Meet on Sand Mining

The authors also need to amend this report quickly. The amendments should highlight the location of the West Fork gage, the implications of that, and limitations on the use of the data – especially by the legislature.

My biggest fear is that sand miners will attempt to use this report to defeat reasonable legislative reforms of the industry. They have used similar reports in the past to do exactly that. I have personally testified in four House and Senate committee hearings about sand mines only to have TACA trot out figures from the 2000 Brown and Root Study. B&R drew similar conclusions because it used the same West Fork gage at I-45.

To protect the scientific integrity of its report and the validity of its recommendations, the authors need to act quickly. The legislature is considering new sand mining regulations at this instant. Such regulations could protect downstream residents from excess man-made sedimentation, huge dredging costs and potential flooding.

The Master Drainage Plan, including Appendix F on sedimentation, is intended to guide flood mitigation efforts for the next 50 years and help inform the expenditure of potentially billions of dollars during that time. The larger report has many good points. But Appendix F is seriously flawed. I hope the partners – City of Houston, SJRA, Montgomery County, HCFCD and their consultants – fix it before lasting damage is done.

Posted by Bob Rehak on 1/28/2021

1248 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.

Details of SJRA Grant Application for Flood Early Warning System in San Jacinto county

The San Jacinto River Authority (SJRA) has applied for a Flood Infrastructure Fund Grant from the Texas Water Development Board (TWDB) to extend its Flood Early Warning System in San Jacinto county. The abridged grant application covers the cost of three new gages that would measure rainfall and flood height (but not flow rates). SJRA would install the gages on:

  • Winters Bayou at SH150
  • San Jacinto East Fork at FM945
  • Peach Creek at FM3081

Complement to Potential HCFCD

These gages would complement four others that Harris County Flood Control District is considering for San Jacinto county.

  • Winters Bayou at FM2693
  • East Fork at SH150
  • Winters Bayou at Tony Tap Road
  • East Fork at SH105
Locations of potential SJRA and HCFCD gages in San Jacinto county

HCFCD could display the information from both its own gages and SJRA gages on its Flood Warning System (FWS) website. The FWS site lets residents view data from all gages throughout the region in one location.

Gage Components and Communications Infrastructure

Equipment installed at each location would include break-away mounting pole, box enclosure with antenna mast, rain gage, river/stream stage sensor, and alert transmitter/sensors.

Components of the system susceptible to water damage would be installed above at least the 0.2% annual chance inundation level, based on Atlas 14 data.

SJRA would transmit data obtained from the gages to its ALERT2 network and display it on its Contrail system. This would let San Jacinto County staff and residents easily access and view the data at any time. These gages would become part of a growing regional network of gages.

Extent of Application

The grant application includes:

  • Verifying that signals can reach SJRA’s repeater tower in Montgomery County.
  • Site survey work at the proposed gage locations
  • Installation of the gages

San Jacinto county would provide ongoing maintenance after training by SJRA staff. That would include including twice-per-year inspection, periodic cleaning, and any required repairs or corrective maintenance.

Project Benefits

The intent of the Flood Early Warning System: to provide early warning to downstream residents, businesses, and property owners. The gages will also help county emergency personnel and responders protect life and personal property which can be moved to a safe location with adequate warning (vehicles, valuables, etc.).

The grant, says the SJRA, would benefit the entire population of San Jacinto County (27,819 in 2018). San Jacinto county lies between Cleveland and Lake Livingston.

Properties downstream of the gages would directly benefit by the proposed flood early warning system (FEWS). But other benefits would extend to the rest of the county. For example:

  • More time to evacuate in advance of a storm could reduce the burden on county-wide emergency services.
  • It could also give the county more time to close roads and tend to other needs during the event.

The gages could also benefit areas downstream of San Jacinto County. For instance, they could provide advance streamflow data to HCFCD.

Gages Located Near Habitual Road Closures

San Jacinto County says multiple major storms have impacted the areas downstream of the proposed gages, including Hurricanes Harvey, Rita, and Ike, as well as storms in 1994, 1998, 2015, and 2016. All caused road closures, high water rescues, etc. These have historically been low population areas, but are growing rapidly.

Additionally, the proposed gage at Peach Creek and FM 3081 could provide some benefits to a small area of Montgomery County, as Peach Creek runs along the county line between San Jacinto and Montgomery Counties. It is possible that some or all of the gaging equipment may be installed on the Montgomery County side of the county line, depending on site conditions.

Cost and Timing

SJRA anticipates the extension of its Flood Early Warning System can be completed in 18 months.

San Jacinto County participated in the process of developing this project. SJRA anticipates the total project will cost $65,000.

All applications for the TWDB Flood Infrastructure Fund Grants go through a two stage process. This abridged application is step one. If TDWB deems the project valuable enough, and if it has enough money, TDWB would invite SJRA to submit a more detailed application for step two.

Posted by Bob Rehak on 7/8/2020

1044 Days since Hurricane Harvey

Details of Four SJRA Grant Applications for TWDB Flood Infrastructure Funds

Yesterday, I ran an article about Texas Water Development Board (TWDB) Flood-Infrastructure-Fund Grant Applications. It incorrectly stated that the City of Houston had applied for six flood infrastructure fund grants. However, five of those listed were actually submitted by other entities, such as the San Jacinto River Authority (SJRA). Below is more information about those grant applications.

Elm Grove Project Correctly Attributed to City

The City did apply for a grant to fund construction of a detention basin on the Perry Homes’ Woodridge Village Property north of Elm Grove Village in Kingwood. It was correctly attributed.

Four Projects Should Have Been Attributed to SJRA

The SJRA submitted four of the five applications that were incorrectly attributed.

  1. San Jacinto River Sand Trap Development
  2. Spring Creek Watershed Flood Control Dams Conceptual Engineering
  3. Upper San Jacinto River Basin Regional Sedimentation Study
  4. Lake Conroe-Lake Houston Joint Reservoir Operations Study

Mayor Pro Tem and District E Council Member Dave Martin personally supported those projects, hence the confusion. TWDB rules for Flood Infrastructure Fund Grants place a premium on support by all affected governmental entities within a watershed. Those include cities, counties, MUDs, river authorities, townships, etc.

Details of SJRA Grant Applications

Here’s more information about those four proposals.

  1. The Sand Trap Study currently underway has to do with identifying acceptable locations for the sand traps. Once identified, the new grant would cover the cost of their detailed design. The proposed study would extend work currently underway.
  2. The Spring Creek Watershed Flood Control Dams Conceptual Engineering Grant would cover the cost of partially designing dams. The San Jacinto River Basin Study identified locations for the dams. But it did not look at construction details. The new study would look at things, such as environmental impacts, utility conflicts, height of embankments, size of reservoir, etc. It continues work to date in the Spring Creek Watershed. San Jacinto River Basin Study partners have not yet released the locations.
  3. The Regional Sedimentation study builds on KBR’s work in 2000. KBR studied portions of the watershed that drain into Lake Houston, but not the East Fork, Caney Creek and Peach Creek. The new study has two objectives: understand where sediment is coming from and what can be done to reduce it. For instance, if the sediment is coming from new developments or sand mines, there may be a need to look at regulations that affect those.
  4. The Lake Conroe-Lake Houston Joint Reservoir Operations Study would look at the best ways to operate the two dams under different storm scenarios. It would assume the construction of additional floodgates on Lake Houston. It would also model storms approaching from different directions. The study will answer questions, such as “What would the effect of pre-releasing water into Galveston Bay be on Cities such as Baytown if a hurricane approaches from the south?” The deliverable: an operations plan.

Sedimentation and Its Role in Flooding

Two large sources of sediment: sand mines and new developments. Here the drainage for the Artavia development tries to find a path to the West Fork, through or around two sand mines. One of the mines was cited by the TCEQ for discharging 56-million gallons of sediment-laden wastewater into the West Fork.
The City, County, State and Federal Government are still working to remove the West Fork Mouth Bar, 1040 days after Hurricane Harvey. This bar is partially the result of excess sedimentation. During Harvey, this bar formed a partial dam that contributed to the flooding of more than 4000 homes and businesses.

More East Fork Gages in San Jacinto County

In addition, the SJRA has applied for a grant to purchase several more stream gages in San Jacinto County. San Jacinto County lies between Cleveland and Lake Livingston.

San Jacinto County partnered with the SJRA on that grant and would provide ongoing maintenance and operations if the application is successful.

Benefits of Additional Gages

Those additional gages would extend the flood-warning time for people in the East Fork Watershed. Such information is crucial for developing evacuation plans in emergencies.

The gages would also help inform the gate operations at Lake Houston. During Imelda, the East Fork received ten times more rain than the West Fork, but the West Fork has far more gages. That hindered understanding of where the danger was coming from and when it would strike.

As news becomes available about other grant applications in the San Jacinto Watershed, I will post it here.

Posted by Bob Rehak on 7/4/2020

1040 Days after Hurricane Harvey