The "cloud burst" that drenched a mid-section of St. Louis County with nearly four inches of rain early Monday morning is only part of why local streams and creeks swelled their banks, flooding businesses and several busy streets.
Forecasters called it a 25-year rain event, but similar flooding took place just eight months ago and to many county residents it's also reminiscent of flooding in 2008.
Metropolitan St. Louis Sewer District spokesman Lance LeComb said another factor is building and development across scores of county municipalities in the last several decades haven't been coordinated with flooding in mind.
“We have, over a number of years as a community, developed a number of low-lying areas very close to creeks and streams, in the middle of drainage pathways to creeks and streams. And, knowing what we know now, it probably wasn’t the best thing to do,” he said.
The difficulty of addressing flooding in the region is that there is no one entity that manages it, LeComb said. "Each municipality unto itself is what you call the floodplain administrator and they determine how the floodplain is developed and if they’re going to have special requirements mitigating against flooding and so on and so forth.”
LeComb emphasized that MSD is not a flood control agency and only responsible for maintaining current infrastructure, but added that MSD plans to ask voters in the next few years to consider approving additional funding to improve storm water infrastructure in areas that flood most frequently.
In the meantime, getting the public to think about building differently and city planners to work together is crucial to preventing floods in the near future, said Dan Sherburne, vice chair of the River Des Peres Watershed Coalition.
"The problem is really that we have our creeks and streams being used as a storm water sewer system,” he said, explaining that the area’s dense concentration of impermeable surfaces like roads, buildings and parking lots drain most rainfall directly into creeks and streams. Planners and developers can make their communities less prone to floods by putting less dependence on local waterways of the River Des Peres Watershed that feeds into the Mississippi.
“I don’t think anybody recognizes what a significant problem this is. It takes events like [this week’s floods] to bring it to people’s attention and unfortunately what they then see as the problem is the flooding. They don’t necessarily see the broader context behind it.”
Sherburne said the simplest solutions involve planning and building with more green infrastructure, such as storm water detention basins, rain gardens, green roofs, and permeable pavement.
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