The Bayou Land Conservancy has added its voice to those raising concerns about the SJRA’s sand trap proposal for the San Jacinto River watershed. The pilot project began out of a desire to reduce sediment buildup in the mouth bar of the West Fork. But it has morphed into something very different – a trench through a sand bar more than 12 miles upstream.

In March 2022, the SJRA published its long-awaited proposal on sediment removal and sand trap development along with a brief summary. It now seeks public comment through April 29, 2022.

BLC’s General Concerns with Study

I posted my concerns on 3/27/22. Yesterday, the Bayou Land Conservancy (BLC) sent me a copy of its letter. It reflected some of the same concerns I had.

• The study did not address what should be the main goal of sediment removal: excessive deposition in the area of the mouth bar downstream of US 59.
• Managing mouth bar sediment deposition, and related flooding, should be kept at the forefront as this project moves forward.
• Sand mining in the floodplain of the San Jacinto West Fork between 1995 and 2017 virtually quadrupled. More than 30% of the river’s flood plain is now being mined. That’s a huge problem that requires other types of solutions to reduce sedimentation from mines, such as improved Best Management Practices.

The group also suggested a need for greater oversight of sand mining by state regulators. It feels an inconsistency exists between in-stream mining via sand traps and the TCEQ’s newly adopted BMPs for sand mining.

BLC’s Specific Concerns re: Recommendation

BLC then went on to discuss the specific recommendation – rock-lined trenches through sand bars outside of sand mines. They listed three concerns:

1. “River migration and erosion: Changes in river course, including erosion and deposition of sediment, are naturally occurring processes. Installation of hardscape or mechanical features within the flowing part of the river will have an impact on this natural process and could lead to increased erosion in the area surrounding the facility, increased sediment transport downstream, and destabilization of the stream to the detriment of the surrounding and downstream communities.”
   
2. “Water quality: 85% of the drinking water needs of the Houston metropolitan region are met by Lake Houston, at the receiving end of the San Jacinto River. Instead of occasional turbidity increase during dredging of the mouth bar, sand trapping could create a long-term elevation in turbidity leading to increased water treatment costs for the entire region, transferring the cost to the public from private interests. Additionally, the riverbed contains chemical components that may need to be addressed in water treatment at additional public expense.”
   
3. “Accountability: the governing legislation created by HB1824 does not address the question of accountability should the private interest in the sediment trap fail to protect the public’s interest or go out of business without remediating the in-stream mining facility.”
   

More Study Recommended Before Implementation

BLC also recommended that two of the study’s recommendations deserve to be prioritized and expanded to provide as much accurate data as possible before sand-traps get further consideration:

1. “Evaluate total annual sediment load transported to Lake Houston, including the area downstream of proposed sediment traps, and compare to anticipated trapped sediment loads.”
   
2. “Perform further geomorphic assessment to address potential downstream instabilities due to removing sediment and to determine appropriate sediment removal volumes.”
   

BLC went on to encourage SJRA to extensively study the holistic sediment story of the upper San Jacinto River watershed. Previous studies point to Spring and Cypress Creeks as major contributors of sediment. BLC wants the sediment loads in those creeks studied as well as the areas downstream of the proposed sand traps.

The group continued, “A science-based, peer-reviewed, methodology of assessing the sediment budget of the watershed is imperative before assuming that removing sediment from any single location on the river will have a positive impact on mouth bar deposition. … Without a basis for understanding the sediment budget for the West Fork, it’s impossible to evaluate (or approve) this project.”

Rivers in Texas Are Public Property

BLC also pointed out that even though HB1824 exempted SJRA and Harris County Flood Control District from any requirement to obtain a permit, pay a fee, or purchase the material taken, in Texas the contents of a river belong to the citizens of the state. “Therefore we all have an interest in the results of this in-stream mining proposal,” said the group’s letter.

The letter concluded, “BLC recommends that extensive further study be undertaken to determine if in-stream mining, i.e. sand traps, will accomplish the stated goal of providing a long-term solution for managing the mouth bar deposition, without creating further instability to the river system and negative impacts to the surrounding and downstream communities.“

Here is their full letter.

The Bayou Land Conservancy, one of the leading environmental groups in the Lake Houston watershed, preserves land along streams for flood control, clean water, and wildlife.

How Taking Sediment Out of a River Can Increase Erosion

Non-technical people may have trouble understanding how taking sediment out of a river can increase erosion. Basically, if you take too much out (more than the natural baseline of dissolved sediment), it can create a “hungry water” effect. Many academics have documented the hungry water effect. It’s especially noticeable downstream of dams, which are notorious for trapping sediment. Rivers with excess sediment transport capacity tend to erode their banks and streamed to compensate.

To Register Your Opinion

To register your opinions, pro or con, with the SJRA, email  floodmanagementdivision@sjra.net no later than April 29, 2022.

Posted by Bob Rehak on 4/9/2022 based on a Bayou Land Conservancy letter to SJRA

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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.