Coincidence?

While editing a passage about rivers, I noticed a strange correlation between seasons and river structure.

Spring moves through summer into fall.

Some rivers start with a spring and move into a fall.

This hippie-dippy realization brought to you by my incessant worry about whether terms are properly introduced before use (I was concerned that "fall" had not yet been defined, when in this case they were talking about the season, not a river structure. And quite obviously, I might add.)