The San Jacinto Regional Watershed Master Drainage Plan has identified 16 long-term flood mitigation projects in Harris and Montgomery counties totaling about $3 billion.

The Harris County Flood Control District, Montgomery County, the City of Houston, and San Jacinto River Authority updated the community through a virtual public meeting on the drainage report on Thursday. The plan aims to help improve the watershed in flood mitigation, assessment, response and community outreach and education.

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The study, which began in April 2019, will identify short term goals, such as developing vision groups, and long term future flood mitigation projects, such as the excavation of stormwater detention basins in the San Jacinto River Regional Watershed. The plan is estimated to be completed in the fall.

“The ultimate goal of this study is to identify measures that can improve resiliency in the San Jacinto Watershed, improving flood mitigation, flood warning and flood response,” said Terry Barr, who oversees the project for the engineering consultant team as the project director.

The watershed spans almost 3,000 square miles, covering seven counties and approximately 535 miles of streams, according to the SJRA. The study takes a regional look at all of the major water bodies connected to the San Jacinto River, such as Cypress Creek, Lake Creek, Lake Conroe, Peach Creek, Lake Houston and Luce Bayou, Barr said.

The study is funded 75 percent by the FEMA Hazard Mitigation Planning Grant Program, while the remaining 25 percent is funded through the four local study partners, Barr said.

“In the last 20 years, there has been a significant attention paid to both flood plain mapping and development criteria with the intent of reducing flood risk,” Barr said. “Since Hurricane Harvey in 2017, that push has been further accelerated, with many (pushing for) community development and floodplain criteria to be much more stringent.”

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The 16 projects included in the study are set in order but may change over time based on a variety of factors, leaving the study as a “living” document according to Barr.

1. Caney-Detention on SH 105

2. Spring – Walnut Creek Detention

3. Spring – I-45 Channelization

4. East Fork – Winter’s Bayou Detention

5. Caney – Detention on FM 1097

6. Peach – SH 105 Detention

7. Peach – I-69 Channelization

8. Spring – Birch Creek Detention

9. Caney – US-69 Channelization

10. West Fork – Kingwood Benching

11. West Fork – River Plantation Channel

12. Lake – Garret’s Creek Detention

13. Peach – Walker Creek Detention

14. Lake – Caney Creek Detention

15. Spring – Woodlands Channelization

16. Lake – Little Caney Creek Detention

The team found 25 projects across the San Jacinto River Watershed and 16 of these were included in the long term reduction plan. The cost to complete the projects is between $2.9 and $3.3 billion and is estimated to save approximately $755 million in damages over the next 50 years. The plan includes $190 million in buyouts for 600 structures located in the five-year floodplain, which have a 20 percent annual chance of flooding.

“It’s also important to note that drainage does not consider political boundaries,” Barr said. “With that in mind, the study recommends that consistent detention policy should be implemented throughout the watershed for any projects that increase flows. The study also recommends that a comprehensive impact analysis be performed for any project that might affect the same flows.”

With such a large coverage area, the watershed has diverse lands ranging from rural to urban centers covering a population of 1.6 million, according to Barr.

It receives about 49 inches of rainfall annually, but unlike that of the lower portion in Harris County, the upper portion of the watershed has a significant vertical relief. There is a 450-foot elevation difference between the headwaters in Walker County and the Houston Ship Channel, Barr said. For flood warning planning, the study recommends adding 26 gages, which would cost as much as $500,000 for installation, not including maintenance.

This plan affects the greater Kingwood area as some of the projects include work to prevent flooding in Lake Houston, where the majority of water from the San Jacinto River Watershed lands.

In the last four years, three major flooding events have caused damages in the watershed. Harvey was the worst with 22 to 34 inches of rain in six days across the watershed. Tropical Storm Imelda also caused damage, affecting some who were still working to recover from Harvey, Barr said.

“Rivers and streams throughout the watershed experienced record inflows and elevations during (Harvey),” Barr said. “Every major stream in the watershed exceeded previous record flow and stage elevation. Thousands of structures reported flooding in Harris and Montgomery and surrounding counties.”

Their modeling shows that structures in the flood plain are actually at a higher risk of flooding than FEMA flood maps show, due to having more accurate rainfall data and better modeling information, Barr said.

The virtual presentation follows the last Kingwood public event for the plan held in mid-December at the Kingwood Community Center.

For more information or to view a recording of the public meeting, visit

[email protected]

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