I see that you are in Anchorage I don’t know which way you are heading or how long you are in Alaska. I spent over 50 days last year in Alaska, seeing the sights and fishing.
Depending on which way you are heading from Anchorage, there are 3 public gold panning areas near Portage Alaska, which is along the Turnagain arm.
We stayed at Williwaw National forest Campground which is on Portage Glacier Rd, about 13 miles from Girdwood, and visited one of the 3. Bertha Creek gold panning area which is about 20 miles from the campground didn’t have much water running at the time and I did some panning but no luck. Bertha Creek also has it’s own small campground but I liked Williwaw because all the campsites were nicer and the sites are paved.
The other 2 are near Hope which are accessed from the Seward Highway via the Hope Highway. They are resurrection creek gold panning area and
six mile creek gold panning area.
The other place I checked while I was on my way to Denali National Park, was near Trapper Creek, it's called the Petersville Recreational mining area which is on the Petersville Road, and it’s about a 30 mile drive off the Parks Highway and Trapper Creek. All but the first 10 miles are gravel and the last 4 to 6 miles are 4 wheel drive or high clearance vehicle.
I didn’t do any prospecting because it started raining hard just after I got there but spoke with a guy who actually camped in the area and showed me the gold he had found.
I stayed at K’esugi Ken campground which is a new state Park Campground with electric sites that had just opened up and was about 20 miles north of Trappers Creek and Petersville Road.
Enjoy your trip, it was hard to come back, we really loved Alaska.