Pretty neat! Not the most accurate near Chicago. When the Des Plains and Chicago river run perpendicular the "rain drop" would skip over the Des Plains and into the Chicago river. Also it would flow toward Lake Michigan, which isn't typically the case.
Yeah the tool struggles a lot with engineered features (dams, canals, etc.) and Chicago is really our quintessential example of this (issue documented a little here: https://ksonda.github.io/global-river-runner/). The US-only version of this tool (https://river-runner.samlearner.com/) is a lot better with the Chicago routes and is generally a little better with routes in the US.
