One of the things I am always interested in as a paddler is not only the current water level but also whether the river is rising, falling or staying relatively stable. The idea behind the arrows is to provide this information at a glance so you do not need to click through to the gauge on the Environment Alberta website. Here is how it is currently set up:

The most current water level is compared against 3 different levels from the past 24 hours and based on the average percentage change in the flow the computer code spits out a result for the end user.