Columbia subject headings:
Agricultural pollution--Prevention--Government policy.
Water quality management--Government policy.
Water--Pollution--Prevention--Government policy.
Harvard subject headings:
Agricultural pollution--Prevention--Government policy.
Water quality management--Government policy.
Water--Pollution--Prevention--Government policy.
Princeton subject headings:
Agricultural pollution--Prevention--Government policy.
Water quality management--Government policy.
Water--Pollution--Prevention--Government policy.