https://dashboard.waterdata.usgs.gov/app/nwd/?region=lower48&aoi=default
Specific site I mentioned - https://waterdata.usgs.gov/md/nwis/uv/?site_no=01650500&PARAmeter_cd=00065,00060,62615,62620
I somehow didn't realize there was a gauge right near my parent's house. Been there since 1920s!