Water in Washington DC that flows through its two main rivers is brackish, and the city is a natural tidal marsh. The rivers rise and fall with the tides, and if you go to the national mall you can see the tide change. It’s not that far away from the Atlantic Ocean.
That being said, the natural ecosystems in the area are meant to support brackish tidal water (it’s why Maryland, the state that gave up the land to make DC, is known for crabs and oysters). And it’s why the Obama administration changed the pool to draw directly from the river. It’s better for the environment and better reflects what the land was like before development.
DC residents get their drinking water from the river as well, but it’s treated, and pulled from further upstream where the water contains less salt. (Yes. You can find seashells on the shores/beaches of the rivers in DC)
With the area being a tidal marsh it is 1. Important for the environment because it acts as a giant filter for the water going into the Chesapeake and the Atlantic. And then 2. Supports a diverse ecosystem. However, it’s hot and humid because it’s summer and algae loves that. But ponds and rivers in DC aren’t constantly covered in algae blooms…. In fact it’s not actually a problem here because things are often designed with the fact that this is tidal area in mind.
The fact that the current administration has ignored ALL of this, and now the local wildlife is suffering is directly their fault. It’s actually impressive. DC has never seen something like this until this administration.
It’s a metaphor for everything else. Don’t let anyone else tell you otherwise.