Geology of waterpower sites on Scenery Creek, Cascade Creek, and Delta Creek near Petersburg, Alaska

Dam sites were examined at the outlets of Scenery Lake, Swan Lake, and Ruth Lake which are located on Scenery Creek, Cascade Creek, and Delta Creek, respectively. The Scenery Lake dam site is partly in quartz diorite and partly in hornblende plagioclase gneiss. The Swan Lake and Ruth Lake dam sites are in quartz diorite. The bedrock at these dam sites is suitable for the height of dams that would be required to achieve the full development of the potential power of the streams. No appreciable leakage from the reservoirs is anticipated.

Tentative tunnel routes for conveying the water from the lakes to powerhouse sites at or near tidewater were examined. The tunnel routes from Scenery Lake and Swan Lake would be in quartz diorite. The tunnel route from Ruth Lake would pass through quartz diorite and diorite gneiss.

The geologic examinations described in this report indicate that the development of the potential power of the streams under consideration is feasible as far as geologic conditions are concerned.