Beta version, just noticed this.
its like an app, but you just use it in your phone's browser. I only played a little bit, but found it didn't have the gauges I need. It has lots of little gulches, but not the rivers and creeks. Maybe I was on the wrong page or something.
Anyway check it out and provide them feedback, so they know we care and want it to work.
Here's what you type into your phone: m.waterdata.usgs.gov
Here's a link to the tutorial:
Using USGS Mobile Water Data — USGS Water Data for the Nation Help System
If you find where to click for useful river flows, please share.