Below are markers you can use to judge the river height. The first will be coming in and the later leaving cabin. If in doubt ask before you plunge.

Marker Stone
This stone is located on the right-hand side of the bridge,
at the waters edge coming in, if you don't see this rock forget
crossing. If water is flowing behind the rock, I wouldn't cross.
If you see 2/3rds of the rock out of the water High Profile vehicles
can cross. Judge the water level from the cabin side of the rock.
Cars can cross when the middle of the bridge is out of the water.

Corner Marker
From the cabin side of the river you can judge if the crossing is
crossable, by looking at the left-hand corner of the bridge.
If you don't see any of the bridge concrete then crossing is very questionable.
If you do see a corner of the bridge concrete out of the water like
the image above then you can cross taking caution.

Caution means don't get a running start and hit the water as fast
as you can, but drive slowly to the dip, then you can pick up a
little speed if need be. Going to fast can cause your vehicle to
be washed off the bridge or drowned out the motor.
(just a little tip for those who aren't sure)