US cities' aging sewer systems cannot cope with the ever increasing demands. At peak times, like during heavy rains, untreated sewage is directly released into waterways.

Rather than building new sewage tunnels and in general upgrading the sewage treatment capacity, the Trump administration instead makes it easier to dump the raw sewage into waterways.

In some cases, hopefully the cities are using this as a temporary measure. New York TImes writes that Washington D.C. dumps its raw sewage 15 to 20 times a year to Anacostia River. According to the newspaper, the city is meanwhile building 3 new large tunnels to tackle the problem.

In other cases, Trump Administration's flexibility may make some cities to be less willing to allocate the funds for building new sewer systems, damaging the environment and endangering the public health.

https://www.nytimes.com/2020/01/24/climate/epa-sewage-rivers.html