Well..............I've been by there in person, looked around and then called the Town Hall from the creek... Actually, you can't pan or sluice at the "beach". Just below the beach is a sign on the creek that basically says one can prospect below the sign.
When I called the Town Hall and talked to the lady she said I could pan or sluice from that sign all the way down stream to the Hwy 285 bridge that crosses the creek/Platte River. Someday I'll get their $5 permit and go panning and/or sluicing.
That area was worked hard with a big bucket line dredge, so pretty cobbily and rocky. I've only heard of folks getting fine flakes and specks...
Looks like it's $5 a week or now $35 a season: http://fairplayco.us/docsforms.html
Good luck. HTH,
Randy "C-17A" www.goldadventures.biz