The obvious trail often crosses rivers in places that are easy enough to handle when the water level is low. When the water is high, there may be other, better routes. Before you plunge in, be sure that you feel comfortable and confident. It might be better to walk along the shore a bit to find a safer route. Look for the easy way.
Currents are slower and water shallower where the stream widens.
It's usually not a good idea to cross barefoot too many obstacles and hazards. If you don't have extra footwear, take off your boots and socks, remove the boot inserts, put your bare feet back in the boots, and cross. On the other side, you'll be surprised to find that the dry socks and dry inserts will actually keep your feet quite comfortable, even though the boots themselves are wet. Cross in the morning. This is because snowfields up high refreeze at night, slowing the melt-off and reducing the force of the stream.