Thank You for your efforts!
I checked out the River app on my phone. I can tag favorites, but after establishing a favorites list, the links to the rivers' conditions in the favorites page are broken - 404 Not Found error.
Behavior: not a bug but something to note...
I noticed on a river with multiple gauge sites that when I select a specific gauge the gauge page will show all the gauge locations. If more than two gauges I have to select one gauge from a menu. If I tag one as a favorite it moves to the top of the gauge page.
Adding; from my Windows laptop, not really a bug but more behavior. I think the favorites tags are cookies based and I had to retag them on a second device.
One thing I kinda wish it would not do is after checking out a gauge page, when I use the back to map link it zooms all the way out to the entire western regional states with the 3 states' gauges view. I would prefer persistence to a smaller area I had been in, instead of having to zoom back in from the western region view.
Some other observations: I am curious about the variability shown on the 3 axis between the cfs and gauge height.
I am pretty spoiled by my subscription phone apps though. For each favorite they have optional labeled "level" tags (I use too high, med, too low) and notifications for a specific level.