HOUSTON — Harris County Commissioners approved tougher development rules in floodplains starting immediately and lasting at least until 2021.
Following the court’s unanimous vote Tuesday, developers must build enough detention to offset possible flooding from new construction in the 500-year-floodplain, or an area projected to have a 0.2 percent chance of flooding each year, in unincorporated parts of Harris County.
The old rule only covered the 100-year floodplain, or the area believed to have a one percent chance of flooding in a given year.
“We’re analyzing how much a new development would increase flooding by and asking the developers to detain that much water so that the net effect is zero,” said Harris County Judge Lina Hidalgo.
Under the new rules, detention basins would hold an average of about 20 percent more stormwater.
“It does because we’re planning for a lot more rainfall now,” said Russ Poppe, Executive Director of the Harris County Flood Control District (HCFCD).
HCFCD staff members say new rainfall depth data collected by the National Oceanic and Atmosphere Administration (NOAA) in December 2017, which includes rainfall from Harvey, shows a 32 percent increase in the 500-year floodplain, a 28 percent increase in the 100-year floodplain, and a 16 percent increase in the two-year floodplain.
County Judge Hidalgo said the building standard hadn’t been updated since 1971.
A group of builders, engineers, and developers had sent a letter to Judge Hidalgo in May asking the county to delay the vote.
Bill Baldwin, a board member with the Houston Association of Realtors, one of the groups included in the letter, spoke with KHOU 11 following Tuesday’s vote. Baldwin said HAR was not opposed to the new regulations but concerned over community involvement.
“Overall, it’s a very positive step for the city and county to become more resilient,” Baldwin said. “If it makes them more resilient, that’s certainly better than flooding houses.”
Baldwin called the cost impact from Tuesday’s vote “fractional” and said the amount of land used for detention would have likely been green space anyway.
“Maybe the soccer field got two feet deeper than it was before,” Baldwin said. “Maybe the lake’s a little deeper. Maybe it’s a little wider.”
Baldwin said he is looking forward to working with the City of Houston on similar regulations in late 2019 or early 2020.
Harris County will use Tuesday’s guidelines until they finish mapping new floodplains in 2021, after which they'll reevaluate their development rules.
ALSO POPULAR ON KHOU.COM