Thread by @39Magilla

@szetoinsitu They have emergency gates to dump the Chicago River and Chicago Sanitary and Shipping Channel (CSSC) into lake Michigan to prevent flooding.

Normally it flows from the Northside past downtown, picking up the Chicago River and into the CSSC, joins the Calumet and flows SW.

@szetoinsitu Normal flow is south on the North south rivers and then to the South West. The Chicago River and bend to the Sanitary Channel have gates to allow flushing to Lake Michigan in times of flooding emergency.

@szetoinsitu They had record rainfall and flushed the river and channel on 5/17. Shortly thereafter, there cases declined.

news.wttw.com/2020/05/18/rec…

@szetoinsitu Four of their five worst hit zip codes in terms of Cases per capita were along the Chicago Sanitary and Ship Channel. The fifth was prone to stormwater flooding.

threadreaderapp.com/thread/1273008…

@szetoinsitu (1) Note how the eastern stormwater drainage route, lined with Combined Sewer Overflow (CSO) outfalls, carries sewage from the most densely populated areas in Chicago into the red zone that contained the highest COVID-19 infection rates per capita.

@szetoinsitu (2) The four contiguous zip codes lie in the red zone along the Chicago Sanitary and Ship Channel. The more northern zip code is the one prone to flooding.

Also, note how few people along the north shore and downtown were infected.

@szetoinsitu (3) This is a summary of the day when the flows were reversed at Evanston and Downtown into Lake Michigan. The red circles are active Combined Sewer Overflow outfalls.

Note how the Chicago Ship and Sanitary Channel was flushed into Lake Michigan.

gispub.mwrd.org/csomaps/

@szetoinsitu (4) Chicago is compelling because:

1. Gov. issued the Stay-at-Home 3/20.

2. The lockdown was ineffective despite better than average drops in mobility.

3. The area recorded record rainfalls.

4. Declines started shortly after the stormwater channels were flushed to the lake.