existed at several additional sites, such as Washington Creek, Oregon Creek, 

 Penny River, and Skeetercake Creek, but a specific blockage was not ob- 

 served. 



Creation of New Habitats 



New aquatic habitat was created at eight sites where mined areas sep- 

 arated from the active channel were flooded subsequent to site closure. 

 These include the Dietrich River-Downstream and Jim River sites as well 

 as the pit sites at Penny River, Dietrich R i ver-Upstream, Prospect Creek, 

 West Fork Tolovana River, Tanana River-Downstream, and Tanana River- 

 Upstream. At the Dietrich River-Downstream site, a wide shallow backwater 

 was created in the spring immediately prior to the site survey, 3 years 

 after mining, and was quickly utilized by round whitefish and Arctic gray- 

 ling. Less mobile species, such as slimy sculpin, had not moved into the 

 area by the time of the survey (12-13 July) but would probably immigrate 

 into the mined area over the summer period. In the river, the most abundant 

 species was juvenile Arctic grayling; the second and third most abundant 

 were slimy sculpin and round whitefish. Removing gravel in an abandoned 

 channel at the Jim River site created a large pool habitat that contained a 

 high density of adult Arctic grayling during the summer. Other species 

 captured included juvenile Chinook salmon, burbot, and slimy sculpin. In the 

 main river, the catch was dominated by Arctic grayling. 



The present configuration of the Penny River apparently resulted from 

 two separate periods of mining. Originally, the floodplain was scraped 

 adjacent to the channel. The channel subsequently diverted through the 

 scraped site and gravel was removed from the original channel, leaving a 

 shallow pit. During the site visit the present Penny River channel, formed 

 by flow diversion through the original scraped area, was heavily utilized by 

 Arctic char juveniles. The pit, created by excavating in the original chan- 

 nel, provided rearing area for coho salmon juveniles and spawning and rear- 

 ing areas for Alaska blackfish and ninespine stickleback. The catch in undis- 

 turbed areas was dominated by Arctic char and coho salmon with Arctic char 

 dominant in the spring and coho salmon dominant in the fall. The occurrence 



184 



