On the East Shore at Gray Creek you pass a sign announcing it as the home of the "Gold Boulder". The classic lost treasure legend, it involves the unexpected discovery, recovery and loss of a fabulously large gold nugget...

The truth, well, it's probably not true. But an interesting story nonetheless.

2 articles covering the tale:

http://www.columbiavalleypioneer.com/?p=16071

And:

https://books.google.ca/books?id=7OFlJZCtvxAC&pg=PA46&lpg=PA46&dq=gold+boulder+of+kootenay+lake&source=bl&ots=ovPeAaCnAp&sig=7Cn_ji1HkPj0hyzzLbtAP0r3IMM&hl=en&sa=X&ved=0ahUKEwiDwb-qpPjVAhUP6WMKHdrABW4Q6AEINDAC#v=onepage&q=gold%20boulder%20of%20kootenay%20lake&f=false