Sligo Creek is at a record height due to today's flash flood, which is a good time for a thread about floodplains in MoCo (please prepare for a thread) - https://twitter.com/WeatherEric/status/1304140277104472065

growing up we'd drive out Georgia Avenue and I'd see this sign in Aspen Hill that said "Flood Area." every time we passed it I expected to see a flood, but there was none -

this area sits in the 500 year floodplain zone, meaning there's a small chance of flooding. it's not big, but you can see a number of homes and apartment buildings sit in it -

you've probably seen photos today of flooding in places like Bethesda and Kensington. these areas are largely *outside* the 500-year floodplain, and the floodplain itself is mostly parkland, a testament to MoCo's gigantic parks system #420parks -

these big parks around Rock Creek, Sligo Creek, Northwest Branch, etc. are there in part to collect water and keep it away from your stuff, and to keep you from putting stuff there. this is good! and yet there is still flooding!

why is that? racism, duh -

many (not all) of MoCo's wealthy neighborhoods sit on high ground, had racial covenants to keep non-white people out, and have single-family zoning to maintain that. a lot of our big parks are protecting these places from flooding today!

as for everyone else -

high housing costs push people to outlying areas, and we built lots of big highways so they could drive in to work. this means more impervious surfaces, which instead of carrying water away, basically directs it to where people live -

Sligo Creek, which is having record flooding today, flows from MoCo into Prince George's County, where entire neighborhoods sit in the floodplain.

one of these places is North Brentwood, the first majority-Black town in Maryland -

in the 20th century, covenants kept Black people from living on higher ground in MoCo. today, if you can't afford a home in MoCo, you go to Prince George's, to towns in the floodplain, which now have the fastest-rising home prices in Maryland. http://ow.ly/meX750Bc6Pq 

like water, people have to go somewhere. all the impervious surfaces from the highways and the houses in the floodplain push the water somewhere else

today in Bethesda, where people 80 years ago though they could keep both people and water out, the streets are flooding

if today's floods freaked you out, they could get worse! especially in places already in the floodplain! we know what to do: let people live on higher ground and let them not have to drive everywhere

okay that's my thread, thanks for watching

whoops, I forgot to mention where the maps came from. Maryland has a website with flood maps for the entire state, and most other places should have flood maps online too. https://mdfloodmaps.net/map/ 

Maryland’s first majority-Black town, and mostly located in a flood plain https://twitter.com/route1reporter/status/1304184250023981057