Cathy Dunn was among the first residents to move into the Norchester neighborhood in 1973, and her home had never flooded until the Tax Day flood of 2016. She rebuilt, thinking it was a one-time event, only to see her home flood again during Hurricane Harvey in August 2017.

Wanting to advocate for her 400-plus neighbors whose homes also flooded, Dunn got involved with her homeowners association, local flooding groups and her municipal utility district to fight for solutions.

“We have all these new young families that look just like I did; I was a young bride when I came and just wanted to raise a family, and it’s beautiful out in the woods,” she said. “And now these people have the same dreams I had, ... and I don’t want it to turn into a nightmare.”

Dunn and thousands of other Cy-Fair residents could soon find relief from flooding once a new plan for the watershed is implemented.

In July 2020, Harris County Commissioners Court approved a $1.4 million agreement for engineering firm Jones & Carter to develop the Cypress Creek Program Implementation Plan, which was released in January and recommended nearly two dozen stormwater detention basins be added to the Cypress Creek watershed. These recommendations would help reduce flood risks for more than 3,000 structures between Hwy. 290 and the Hardy Toll Road over the next several years, according to the report. The projects are expected to cost $597.1 million, and flood control district officials are working to identify funding sources.

If these proposed basins are all added, engineering officials in the report estimate 39% of structures would be removed from the 10-year flood plain, 21% would be removed from the 50-year flood plain and 19% would be removed from the 100-year flood plain. Structures in these flood plains have a 10%, 2% and 1% chance of flooding in any given year, respectively.

Since Harvey, the Harris County Flood Control District has completed or initiated several mitigation projects and studies. More than $291 million of the $2.5 billion flood bond Harris County voters approved in 2018 was set aside for Cypress Creek projects, including home buyouts, maintenance work to restore channel conveyance capacity, storm debris removal, drainage infrastructure repairs and detention basins.

Jonathan St. Romain, a department manager with the HCFCD, said stormwater detention basins are more effective than channel modifications. Detention basins temporarily store stormwater until it can make its way back into a nearby channel. Most of the projects would be multipurpose.

“We understand that communities need and desire these projects as well that allow for flood risk reduction while at the same time, you know, it sort of is common sense that you can look at a detention basin that is this open area of land that is ... good and useful to put trails around and to provide pockets of parks and other features,” St. Romain said.

Basin basics

The Cypress Creek Program Implementation Plan evaluated 49 potential stormwater detention basin sites before narrowing the list down to 23 basins distributed throughout 11 areas along Cypress Creek.

Factors weighed in the prioritization process included flood risk reduction, existing condition, project efficiency, social vulnerability index, partnership funding, long-term maintenance costs, environmental effects and the potential for multiple benefits, according to the report.

Cypress-area projects in the top priority tier include a group of four basins at Cypresswood and Jones roads as well as the extension of a basin at Cypress Park. Construction is expected to begin in 2025 and 2027, respectively. Another basin is slated for construction in 2027 near Telge and Pleasant Grove roads, according to the report. Combined, these projects should remove more than 2,200 structures from the 100-year flood plain.

A basin proposed in the Faulkey Gully area was deemed infeasible because it would have cost $358.7 million and only benefited about 83 structures. Six basins are slated to move forward in the Cy-Fair area along with 16 in the Spring area.

Ultimately, 22 of the 23 sites were recommended in the prioritization process. According to the report, these basins combined would hold about 12,800 acre-feet—or 4.17 billion gallons—of excess stormwater.

Michael Baker International’s Cypress Creek Watershed Major Tributaries Regional Drainage Plan update from February 2020 recommended about 26,500 acre-feet of stormwater detention be added to the watershed, which would be enough space to store 8.6 billion gallons of water. An additional 30,000 acre-feet, or nearly 9.8 billion gallons of water, is recommended upstream in the Little Cypress Creek subwatershed.

St. Romain said while adding 56,500 acre-feet of detention is feasible, it would take years to achieve.

“That’s really the reason we have this plan is to have a long-term road map so that we can get there, but everybody—us included—we’ve got to understand that kind of scale can’t happen quickly,” he said.

Mitigation efforts

Jim Robertson, who serves on the board of directors for the Cypress Creek Flood Control Coalition, was pleased to see a prioritized list where detention basins could be located—a first for the watershed, he said.

Eric Heppen, who works on the technical staff for Harris County Precinct 3 Commissioner Tom Ramsey, said while getting structures out of the 100-year flood plain is critical, the commissioner’s approach to flood mitigation is to act now and help as many residents as possible.

“Residents want to know, ‘For that two-year storm, that 10-year storm that truly happens more frequently, am I protected?’ We do try to do the most that we can to get the best benefits to the taxpayers,” he said.

As of the 2020 census, more than 450,000 individuals live in the Cypress Creek watershed, and another 45,000 live in the subwatershed of Little Cypress Creek, according to the HCFCD. The population has grown by 31% and 57%, respectively, in the past decade.

St. Romain noted the watershed is highly developed and historically prone to flooding.

Heppen said he believes new development is not contributing to higher flood risks because developers are now required to meet stricter regulations. This means neighborhoods developed in the 1960s, 1970s and 1980s—such as Norchester, Grantwood, Windwood, Lake Cypress Estates and Enchanted Valley—tend to be more prone to flooding.

“Even if development continues, they’re developing much more responsibly. ... Developers have learned that they can build even more detention [than what is] required, and it tends to be an amenity towards their development,” Heppen said.

Next steps

Several basins in the top priority tier are underway in the Spring area. The HCFCD is seeking funding partners throughout the development of the 22 basin projects, and property acquisition on the sites the district does not already own has already been taking place, St. Romain said.

Once these are developed, St. Romain said the district could revisit the original list of 49 sites.

Dunn said after serving as Norchester HOA president and playing a part in revitalizing Norchester, she decided to also run for her MUD board in the upcoming May election. She said she would like to see local MUDs work together to have a greater impact on flood mitigation and help secure funding for future projects.

“They have done some projects. What they’ve done so far, the water is moving faster, but if we get 15 or 20 inches of rain in 24 hours, I think we’ll still be doomed,” Dunn said.

For more information, tune in to the flood control district’s March 9 community engagement meeting from 6:30-7:30 p.m. here.