According to Postmaster :

Are you lost, just quarrelsome or both. Have you ever actually measured
a ground loop current in access of one amp. Natural ground gradients
never produce currents of 5.5 amperes. Ground loops occur from voltage
gradients that are measured in millivolts. The only hazard a naturally
occurring ground loop causes is to electronic signal quality between
digital equipment connected to grounds with differing potentials.

Two comments:

1) Ground loops cause the flow of continuous current from one place to another,
usually including one or more "sub-optimal" connections. Ie: buried/wet.
Which can lead to galvanic corrosion and connection failure. Even if the
current flow is very low...

2) It's not just "natural" ground gradients you need to worry about.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.