Borders of Sewage Farm Districts

Sewage Farms
(in operation)

	Supplied with Mechanically-Cleaned Sewage Water
	Supplied with Mechanically-Biologically- Cleaned Sewage Water

Sewage Farms (discontinued)

	before 2000
	before 1990
	before 1980
	before 1970
	before 1960
	before 1930

Special-use Areas

	Sludge Drying Areas (as of approx. 1965)
	Sedimentation Tanks (as of approx. 1965)
	Intensive Filtration Areas (1975-1985 northern sewage farms; 1978-1989 southern sewage farms)
	Sludge Storage Areas (in operation)
	Sludge Storage Areas (out of operation)
	Depositing of Sewage Sludge on Agricultural Areas (1980-1985)
	Fining Ponds for Follow-up Purification of Sewage Plant Outflows
	Composting of Sewage Sludge (in operation)