Hoover Dam? That made a thought flash thru my brain "multiple dams all at once". Good God! (slaps self to calm hysteria)
Your#122) Correct, but more at the Colorado & Green rivers above it.
('Dirty' river basins [watershed] would 'dirty' So. California's water)
'Heartland' more at Chicago (Board of trade, etc.)
Or, any and all automobile/gas/fuel refineries areas.
Not to exclude Atlanta and Houston!!
IMHO