Harris County proposing dramatic overhaul of floodplain regulations

After Harvey, thousands of homeowners learned they were in a floodplain. After Harvey, thousands of homeowners learned they were in a floodplain. Photo: Brett Coomer, Staff Photo: Brett Coomer, Staff Image 1 of / 75 Caption Close Harris County proposing dramatic overhaul of floodplain regulations 1 / 75 Back to Gallery

Nearly three months after Hurricane Harvey, Harris County is proposing using 500-year floodplains instead of 100-year floodplains for new development, the first significant overhaul of county elevation requirements in nearly two decades.

The regulations, which still must be approved by Commissioners Court, would force developers to build new homes eight feet higher than previously required in some flood-prone areas.

They would also, for the first time, open up a broader geographic area to regulation by forcing developers building in 500-year floodplains to meet stricter elevation standards. Currently, there is little regulation outside the 100-year floodplains.

"Any time we can figure out how to make our regulations better and our infrastructure more resilient, we want to do it," said county engineer John Blount. "We don't want to be permitting houses that would flood. It's not good for the county. It's not good for people that are in the houses. You shouldn't be building houses at an elevation you know they're going to flood."

The move comes nearly three months after Hurricane Harvey devastated the county, dumping more than 51 inches of rain and flooding about 136,000 homes and other buildings and killing dozens of people.

The storm prompted a sweeping reexamination of the region's flood control strategy.

Harris County Judge Ed Emmett last month proposed 15 different measures to bolster flood control, including expanded regulations, the construction of a third dam and reservoir system in the northwest area, and an effort to push the state to give Harris County the authority levy a sales tax to pay for costly flood-control measures.

A majority of the Harris County Commissioners Court has also indicated support for a flood-control bond referendum that could be upwards of $1 billion. The county is working on buying out more than 200 homes flooded during Harvey that sit in floodplains.

Commissioners could consider the regulations as early as Dec. 5.

Raising requirements

The newly proposed regulations focus on the booming unincorporated region as opposed to areas within Houston city limits. Unincorporated Harris County has added nearly 1 million people since 2000, more than three-quarters of the growth in the county since 2000.

For some areas along the San Jacinto River, Spring Creek and Cypress Creek, the difference between the new and old regulations — 500-year versus 100-year flood levels — could be several feet of elevation required for new homes, which could increase the cost of development by thousands of dollars.

A 100-year event refers to a storm so severe that it has a 1 percent chance of occurring in any given year, and would equate to between 12 and 14 inches of rainfall in 24 hours. A 500-year event has a 0.2 percent chance of occurring in any year, and would equate to between 17 and 20 inches of rainfall in 24 hours.

Floodplains and flood levels are mapped by modeling how water spills out of the creeks, bayous and ditches during those storms, and how high the water would rise.

The package of proposed regulations also includes measures to make elevation requirements even more stringent in floodways — channels where water is expected to flow during floods — as well as reinforcing new homes for high wind speeds.

"I think it's a great, great thing to do," said Precinct 3 Commissioner Steve Radack, whose precinct on the west side of the county is one of the most fast-developing portions of the region. "I will support this."

Adding to home costs

The move is also being met with optimism from developers and critics of the county's flood control practices alike.

Ed Taravella, chair of the developers council at the Greater Houston Builders Association, said the association will support the proposed regulations. He said developers, for the most part, avoid building in floodplains.

According to data provided by the county, 4,131 single family homes, or about 350 every year, have been built in 100-year floodplains since 1998, when the county's current elevation requirements were first adopted.

Since the last update to the county's infrastructure regulations that govern new subdivisions in 2009, more than 75,000 homes have been built in the county. About 467 of those flooded during Harvey, indicating the devastation hit largely older homes.

"I'm fine with what they're doing now," Taravella said. "It's legacy subdivisions that are the ones that were hardest hit."

Taravella said for builders who do build in floodplains, the increased cost of elevating homes would likely be passed onto the home buyer.

"We'll just price it into the cost of the home," he said.

Jim Blackburn said the current regulations were a long time coming, but the county and other public officials need to further refine their regulations.

"The question is whether the 500-year is large enough," Blackburn said.

Meanwhile, the proposed regulations would not govern development in the city of Houston. City regulations require new homes built in 100-year floodplains to be elevated one foot above the 100-year flood level — less than the 18 inches that the county currently requires.

Houston Chief Resilience Officer and "flood czar" Steve Costello said the city has not yet made any proposals regarding new floodplains, but has called a meeting in December among city staff to start the discussion. He said the city would consider the county's changes.

"There's no guarantee we will formally adopt everything that they have done," he said. "Obviously we don't want different criteria at the end of the day."

The full proposed regulations can be read here.