Columbia subject headings:
Agriculture--United States--Congresses.
Drainage--Congresses.
Erosion--Congresses.
Hydraulic engineering--Congresses.
Watersheds.
Harvard subject headings:
Agriculture--United States
Agriculture--United States--Congresses.
Drainage--Congresses.
Drainage.
Erosion
Erosion--Congresses.
Hydraulic engineering--Congresses
Princeton subject headings:
Agriculture--United States.
Drainage.
Erosion.
Hydraulic engineering--Congresses.