Residents of the Columbia Basin Irrigation Project Area are, and will continue to be, faced with problems involving the disposal of sanitary sewage and wastes from industry. Since there are no continuous streams in the area, waste material must be disposed of either on land or in reservoirs or in the drains provided for return irrigation water.

Most drains on the upper project area discharge to Moses Lake or Potholes Reservoir which supply some of the irrigation water for the lower area. Other return waters will eventually find their way by various drains and waterways to the Columbia.

There are extensive plans for the recreational development of Moses Lake, Potholes Reservoir and other lakes in the project area.

The preservation of water quality in the surface and groundwaters of this project is important since such quality will affect the use of the water for irrigation, recreation and water supply. The quality of the Roosevelt Lake water used for irrigation will undoubtedly be altered in some manner by the leaching action in the soils to which it is applied. This change in quality is sure to affect its subsequent use, but is a change which for the most part is beyond control. Changes in water quality due to sewage and wastes, however, are subject to control and it is imperative that such control be exercised.

In addition to the public health problem, one of the most aggravating problems which is sure to exist in a presently undetermined degree is that of algae growths. These growths will appear in drains, lake and reservoirs in which return water is collected. Soil leachings will provide some of the nutrients for this growth. Sewage and industrial wastes can, if not controlled, substantially add to these nutrients. Algae growths may interfere with the use of the waters for recreation and will substantially increase maintenance on drains, canals, farm laterals, and sprinkler systems.

Another problem involved in the control of wastes discharged to the return water is that of preventing the discharge of certain material in quantities which will affect the soils or crops to which the water is applied. It is not presently known that such materials will result from industrial developments in the area; however, it is desirable that their presence be anticipated and regulations for their control be applied.

Other problems which should be similarly anticipated are the effects of waste materials on domestic and industrial water supplies. Most of the present supplies are taken from underground sources and further demands for increased supplies will result from the development of the area. In this connection, sanitation is a primary factor, but is not the only consideration. Odors, tastes, color, turbidities and the presence of certain chemical compounds are factors influencing the quality of a water supply. Since sewage and waste disposal must be accomplished in many cases by land surface or subsurface application, the possible effects on groundwater supplies require that these methods of disposal be carefully controlled.

In order to provide for the necessary control of the anticipated effects of sewage and waste disposal on water quality in this area, the following regulations have been adopted. These regulations may be altered from time to time as experience dictates.

Attention is here directed to another set of regulations of ecology which apply in this area. These are "Rules and regulations for the submission and approval of plans for the installation of public sewage and industrial waste works and for the operation of such works." (See chapter 372-20 WAC.)