Behind the dam, Lower Granite Lake extends 39 miles (63 km) east to the confluence with the Clearwater River at Lewiston, Idaho, and allowed the city to become a port.

[2] Just downstream (northwest) of the dam on the east bank, Boyer Park was constructed by the Corps of Engineers and opened in April 1973.

The Corps of Engineers has installed new devices, such as removable spillway weirs, in an attempt to make the dam less harmful to juvenile salmon.

Authorized by Congress in 1962,[24] a fifth dam on the lower Snake River was proposed several miles upstream (south) of Lewiston.

[25][36] Following the September 11 attacks in 2001, the road across the Lower Granite Dam was closed for over six years; it reopened for weekend traffic in May 2008.