OK, I'll just take another wild guess - Rho Creek?

"if you're alert you'll find a spring" – Fadeaway Springs? 

+

"They had to keep their guard up in those days" – Rho Ridge Guard Station?

Alright Bob, Corral Springs. And that's my final answer.

Donovan, I think your answer fits his clues the best.

I was looking at the 1956 USGS and it shows that trail continuing on the other side of the river. Has anyone ever found any remnants?

After comparing today's map to the '56 version it looks like the trail was rerouted or that the earlier map wasn't accurate.

Corral Springs is on my list of "to dos" this year.....

I have found those 56 maps to be kinda general as to trail locations.

Someone has looked across the way. Sposenly 511 came down from Frazier to there.

D.