From Broadcasting Yearbook 1968.
WTOA(FM) January 1949: 97.5 mc; 100 kw. Ant 457 ft. 896 -0975. Nassau Bcstg Co. (acq 12- 1 -64).
Rep: Masla; Selective Bcstg Adv. Herbert W. Hobler, pres; Tony Lupo, gen mgr; Bob Alexander,
prod mgr; Albert Makkay, sis mgr; Arthur A. Silver, chief engr.
So, something changed between 1969 and 1970. Obviously the antenna height is one thing that changed. The antenna may have moved. Perhaps when they moved the antenna, the power had to drop. Was it ever 100K? I wasn't aware that the FCC licensed stations at that power in highly populated areas between Philadelphia and NYC. So it might be Herb Hobler's bravado in that listing, since those listings were submitted by stations. But I'd have to do more investigation. This is why people consult Scott Fybush.
The "error" suspicion is based on the station's own ad in the 1969 Broadcasting Yearbook showing 50 kw while the actual YB listing showed 100 kw. The ad immediately follows the standard listing on page B-109 of that Yearbook.

I felt a disturbance in the force...
Anyway....I went to the FCC history cards, armed with a pretty good idea of what they would say.
And I was right: 97.5 signed on in 1947 as WTOA, and it never ran more than 14 kW until 1967, when it went for a maximum power increase.
Had it done so before 1964 when the rules changed, it might have been able to get more than 50 kW. But once the class structure for FM was codified, class B stations were limited to 50 kW, and that's how much 97.5 got.
(So why did it say 100 kW in BY? Some FM stations played the game, in that early era of using both h+v polarization, of adding up their power in each plane... and 50 h plus 50 v indeed "adds up" to 100.)