Historic rainfall saturated Southeast Texas between May 26-28, resulting in 880 homes in Montgomery County sustaining major flood damage, 150 roads submerged underwater and 400 high water rescues.
Five-16 inches of rain fell in Montgomery County during what has been classified as a 100-year flood—a rainfall event that has a 1 percent chance of occurring in any given year. In some areas of the county, as much as 16 inches of rain fell in 12 hours, classifying the episode as a 500-year event. County Judge Craig Doyal signed a disaster declaration for Montgomery County on May 27 for the second time in two months.
“To have the kind of rain that we had back in April is always surprising,” Doyal said. “But to immediately turn around within 30 days and see the same type of event again is almost unbelievable. I’ve never seen this much rain back to back, and I’ve lived my whole life [in Montgomery County].”
This 1 percent rainfall event follows a similar flood that took place April 17-24, during which 5-15 inches of rain fell in Montgomery County. During that time, 600 homes were left with floodwater damage and 50 homeowners applied for the Federal Emergency Management Agency’s voluntary buyout program, according to the Montgomery County Office of Emergency Management.
In response to the rainfall events, The Woodlands Joint Powers Agency is conducting a drainage study in pursuit of possible improvement projects. Rapid development is a big factor in increased flooding and because Montgomery County is still being built out, low impact development could mitigate some of these issues.
During both instances, the Timber Lakes/Timber Ridge subdivision, located just south of The Woodlands, was one of the most affected suburban areas in the county, 22 percent of which is located within a flood plain. According to county officials, the flooding in May caused more damage to Montgomery County than the April flooding, wreaking havoc in the southern and western areas of the county, such as The Woodlands and Magnolia.
“Timber Lakes/Timber Ridge was built before [the National Flood Insurance Program]was enacted,” TWJPA General Manager Jim Stinson said. “So those homes flood more often and more severely during major rain events because many of those homes were actually built below the 100-year flood level.”
The floods also damaged the Spring Creek Greenway, which Montgomery County Precinct 3 and Bayou Land Conservancy volunteers will be working to restore over the next several months.
The Woodlands’ existing drainage system is composed of flood plain areas surrounding natural bodies of water, an underground storm sewer system, and manmade detention ponds and drainage ditches. This system is designed to accommodate a rainfall intensity of about 1 inch per hour, Stinson said.
“Anytime you have rainfall coming down at an intensity greater than 1 inch per hour, the pipes are going to get full, and you will observe ponding in the roadways,” Stinson said. “The ponding in the roadway is intended to happen. The goal is to keep that stormwater contained in the roadway, but for it not to go into single-family homes and other structures.”
After Tropical Storm Allison flooded the Greater Houston area in 2001, Stinson said Montgomery County officials conducted a detailed analysis of the flooded areas and made adjustments to the storm drainage system in an effort to provide relief.
“We are looking at that again from the storm of April 18,” Stinson said. “We have a team of engineers and surveyors that are out in the community taking elevations and reviewing data to see if any adjustments can be made at a reasonable cost to improve the drainage system.”
According to Doyal, two of the biggest barriers in the county’s ability to address these issues is a lack of funding and a lack of jurisdiction.
“We don’t have a flood control district,” Doyal said. “We’ve got a couple of drainage districts in south [Montgomery County], but in the past when we’ve tried to create a flood control district, it just didn’t gain traction because people who don’t flood don’t want another taxing entity to accommodate flooding. We’re seeing more and more people starting to flood though, so it may be something we need to revisit.”
As it stands, developers in Montgomery County must design roads to accommodate 10-year flood events to meet the county requirement, according to Doyal. The state requires roads to accommodate for 25-year flood events.
“It is vitally important to adhere to these requirements to lessen the impact of devastation that occurs when we experience a major flooding event,” County Engineer Mark Mooney said. “These types of storms are dangerous, requiring rescue operations, emergency personnel and many months of cleanup, affecting all those in the pathway as well as proving to be extremely costly for residents and governmental agencies.”
Doyal said after the flooding in April and May, he believes more people will be interested in the possible formation of a flood control district, and that it could be an item voters can decide on in a future election. A Flood Control District would give the county both the funding and the jurisdiction to better address flooding issues.
“It would require some kind of referendum,” Doyal said. “A few years ago, there was an attempt to create a flood control district, but it just got hammered in the referendum. I know now that certainly a lot more people would be paying attention to it, but I think we’ll still get some of the same pushback.”
In addition to improvements to the existing drainage system, Montgomery County is also looking into an early warning system to let citizens know when and where they can expect flooding.
According to Jeff Taebel, director of community and environmental planning for the Houston-Galveston Area Council, the Greater Houston area is projected to grow by an additional 3.5 million residents by the year 2040. With that growth comes more development and urbanization. Montgomery County’s population, specifically, is projected to double and reach 1 million by 2030.
Taebel said concrete and infrastructure have serious ramifications when areas are drenched with heavy rainfall.
“[Development] certainly has to have an impact [on flooding],” Doyal said. “Anytime you put more asphalt, in terms of streets, and more rooftops covering up that impermeable area, it’s going to change the way that water flows. It’s going to change the amount of water that doesn’t penetrate into the ground and has to run off somewhere.”
In an effort to combat this additional concrete and infrastructure, H-GAC released the study, “Designing for Impact: A Regional Guide to Low Impact Development” in May, for the benefit of developers and local governments in the region that can implement its principles in future project planning.
“The idea of [low impact development]is to really utilize natural systems when possible, or mimic them to hold and clean stormwater when designing new development projects,” Taebel said.
Although it was not called low impact development in the 1970s when The Woodlands was being built, Taebel said the master-planned community implements a lot of the same principles and sets a good precedent for the rest of Montgomery County.
“There are some good projects in The Woodlands already,” Taebel said. “I think Montgomery County is really fortunate to have that tradition of designing with nature already and having one of the leaders in the region and in the nation with The Woodlands. I would say the county is pretty well-positioned to take advantage of [low-impact development] especially with all the growth that’s coming.”
Stephanie Prosser, interim executive director of the Bayou Land Conservancy, said incorporating natural environments into developments can not only aid in keeping developments from flooding, but they can also serve as an amenity to the community.
“We want to use the Spring Creek Greenway kind of as an example of a successful collaborative effort of organizations,” Prosser said.
Gov. Greg Abbott issued a disaster declaration June 1 covering Montgomery County in response to the May flood. If the federal government does the same, FEMA will be able to start responding to aid requests.