The Alaska Gastineau Gold Mining Company completed the Salmon Creek Hydroelectric Project in 1914 to power its mine and mill at Thane. While some portions of the original project have been abandoned or replaced, other original parts are stilll in service today, providing power for Juneau.
In celebration of this centennial, I've hidden a series of caches along the trail. There is no swag in these caches, but there are cards with historic photos and an explanation of some of the history you are seeing along the way. Feel free to take the cards to read along the trail, or just look at the laminated copy inside the cache if you don't want to carry the paper.
The caches, 6"x8" snap top containers, are all fairly easy to find, and the hints are dead giveaways. You may want to try it without the hints at first.
Cache #2 leads you to the remants of the old lower penstocks.
What about Salmon Creek History Cache #1? The first photo in the series is in Lower Salmon Creek Cache, GCWH06 (Thanks Nanuk of the North). You'll want to find this one before you start the rest of the hike.