FISHERY BULLETIN: VOL. 87, NO. 4. 1989 



4 8 12 



Scale in Miles 

 Figure 1. — Location of the study area in southeastern Washington. 



described in relation to bathymetric and hydro- 

 logic characteristics of the river. 



STUDY AREA 



The Columbia River is about 330 m wide at the 

 study site (river km 613) with average flows of 

 3,400 m'Vs. The channel is straight, and there are 

 no islands or other major changes in the channel 

 configuration within 6 km of the site. The river 

 bottom slopes gradually from the Benton County 



side of the river to a distinct channel and rises 

 steeply to the opposite shoreline (Fig. 2). Bot- 

 tom substrate consists primarily of packed cob- 

 ble, >10 cm in diameter, and boulders. 



River flows in the Hanford Reach are con- 

 trolled by releases at upriver dams in response 

 to hydroelectric power demand and fish passage 

 requirements. Seasonal flows at the site ranged 

 from 1,220 to 5,270 m'Vs in the summer of 1983 

 and from 2,600 to 6,330 m'Vs in the spring of 

 1984. River depths varied by about 4 m as a 



776 



