RESPONSIBLE officials are interested in a waste disposal or treatment facility that is economical to build and operate, requires little attention, and still does a satisfactory job. Disposal by irrigation meets these specifications for some industrial wastes, and it has attracted a great deal of interest recently. Irrigation as a means of disposal is not new; this method was used extensively on sewage farms beginniig in the 1860's and 1870's. The two principal methods of using irrigation to dispose of waste water on the land are ridge and furrow irrigation and spray irrigation. In the ridge and furrow method, wastes are disposed of in furrowed plots. Early systems used a single or a few furrows, and the wastes were directed manually to another furrow when one was full, a technique that can also be used with contour furrows on sloping land. On relatively flat land, two or more plots are usually developed. Wastes are discharged to a main or header ditch, which may be in the center of the plot or at the side, and then flow into the furrows which are nearly level but at a higher elevation. Furrows are 3 to 15 feet apart, 1 to 3 feet deep, and 1 to 3 feet wide. When wastes in one section build up to about 6 inches from the ridge tops, a control gate can be set for overflow into another area. Control gates can also be used to take an area out of service for maintenance or to rest the land. Coinpared with spray irrigation, ridge and furrow systems have a higher original cost and a lower operating cost, and can handle higher volumetric loadings. They have no problems caused by freezing during cold weather. But they are more likely to develop into a nuisance and may require additional land to get farther away from factories, dwellings, or public roads. Because land irrigated in this manner is difficult to crop, grasses are frequently left uncut, but noxious weeds must be destroyed. Disposal by spray irrigation is a recent development in this country. The first installation of this type appears to have started operating in 1947. Only a few had been installed prior to 1950, but since that time use of this method has mushroomed. Wastes are sprayed onto the land, usually through revolving nozzles. Lightweight metal or plastic pipe is frequently used to convey wastes from a wet well or holding pit to the disposal field. Pipe sections can be moved easily to change spray areas, and, in some cases, extra piping and a valving arrangement can divert wastes to different locations. The land does not require special preparation and moderate slopes can be tolerated. Woodland, brush areas, pastures, and cropland have been used successfully for waste disposal. Generally, it has been easier to obtain land for spray irrigation than for ridge and furrow systems. In a few cases, industry has been given use of land in exchange for the wastes and their possible fertilizer and moisture Mr. Schraufnagel is associate public health engineer for the Wisconsin State Committee on Water Pollution at Madison. The article is based on a paper presented at the ninth annual meeting of the Middle States Public Health Association, April 28, 1958, Milwaukee, Wis.