REMOVE

1. landscapes (representations)
2. hills
3. Regionalist (American Scene)

WHAT

1. Grand Coulee Dam (dam) (1)
2. Visual works (hierarchy n … (1)
3. boats (1)
4. construction equipment (1)
5. construction sites (1)

More 

WHERE

1. Nespelem, Washington (1)

WHO

1. Still, Clyfford (1)

WHEN

1. 1936 (1)