Agricultural Land Drainage and Stream Pollution

The inherent characteristics of organic pollution contributed to agricultural land drainage by farm animals are investigated as well as whether this contribution can be a significant problem in stream pollution. The nature of abatement measures is outlined, together with their practicability and effectiveness. Human disease hazards in water-borne animal wastes are reviewed. The Potomac River drainage shed above Washington, D.C., is used as a case example. Calculations for the cited portion of the Potomac River drainage shed indicate that in 1959 the raw waste of farm animals had a population-equivalent (PE) of over 3 million, applied to land surfaces. This PE was over 8 times that of the total human population on a human excrement basis and 4.5 times the raw domestic sewage PE. Farm animal population censuses for 1950 and 1959 showed a 5% increase in cattle population on the drainage shed and of 18% to over 135,000 cattle in the two upstream counties immediately adjoining metropolitan Washington, D.C. Thus, the fate of animal excrement after deposition on land surfaces in this case possesses important potential significance in stream pollution studies and stream pollution abatement. Limited data are cited concerning the actual BOD contribution of agricultural land drainage to a stream under flushing-flow conditions. Study and recognition of problem, process, and control methodology by soil conservation and other measures appear to have been mutually neglected by water pollution, health, and soil conservation agencies. Voids are exposed in an area of growing importance.