2mcchesney I think it is important to mention that strontium at that level (680mg) is not actually "natural." That is not to say it is not helpful. Not sure how much is in groundwater that you cited and of course any website should be viewed with skepticism:
https://saveourbones.com/strontium-science-based-facts-vs-fiction/#:~:text=The%20estimated%20average%20daily%20intake%20from%20vegetables%20and,weight.%20Supplementing%20with%20strontium%20is%20clearly%20not%20natural.
Excerpted: "A typical strontium citrate supplement dosage (around 680mg) is 170 to 340 times the naturally occurring strontium levels in the average person’s daily diet."

My concern is that it makes bones look denser and healthier on DEXA because strontium is denser than calcium and replaces it. So once we take it, the DEXA is likely skewed unless there is a radiologist skilled in interpreting.

Another concern is that the European medical board banned strontium ranelate for a time due to cardiovascular risks. Noone seems to know if strontium citrate poses the same risks. It is back on the market in Europe but only as a last resort for people who cannot tolerate anything else. In the US, supplements are not regulated so we need to be careful what brand we use.

I took it briefly 15 years ago and would consider it after treatment with meds for maintenance. I have been told strontium is not strong enough to deal with osteoporosis that is not mild. It would be dangerous for me to rely on it but those with osteopenia or very mild osteoporosis could try it. Just have to know the DEXA may look better than it is.

ps another issue is how long before strontium leaves the bones...not sure, need to research