Micro climates are everywhere in the mountainous west - canyons to peaks. I forgot what the elevation gain or drop equivalence is for miles going north or south. Good general guideline map, thanks for posting.
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1984 xxxxx
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I checked my NEC library and the requirement to supplement a water pipe electrode first appeared in the 1978 NEC. This section also added the requirement to install a bonding jumper around water meters.
From the 1978 NECH summary of changes:
Art. 250-Grounding
New. 250-81(a), last two sentences
250-81(a) A metal underground water pipe in direct contact with the earth for 10 feet or more (including any metal well casing effectively bonded to the pipe) and electrically continuous (or made electrically continuous by bonding around insulating joints or sections or insulating pipe) to the points of connection of the grounding electrode conductor and the bonding conductors. Continuity of the grounding path or the bonding connection to interior piping shall not rely on water meters. A metal underground water pipe shall be supplemented by an additional electrode of a type specified in Section 250-81 or Section 250-83.
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