WHAT'S HAPPENING TO WATER? — ROBINOVE 385 



Natural water of poor quality must be distinguished from water 

 polluted or contaminated by man and his agencies. The poor natural 

 chemical quality of water is a problem that is not easily coped with, 

 but a great deal can be done to avoid and correct pollution of water 

 in streams and below the surface of the ground. Pollution, the fifth 

 major problem, consists of permitting the entry into streams, lakes, 

 and ground-water reservoirs of materials that are harmful and can- 

 not readily be removed by normal water-treatment processes. These 

 include organic and inorganic waste from municipalities and indus- 

 tries, which may, for example, temporarily lower the dissolved oxygen 

 content of water in streams and lakes to a point where no fish or 

 other aquatic life can live in the water. 



Waste must be disposed of, of course, and disposal of waste into 

 flowing streams has been a practical method for many years. How- 

 ever, the streams must have a large enough flow to dilute the waste, 

 and when the wastes become a large enough percentage of the stream- 

 flow so that the quality of water is objectionable, the stream is pol- 

 luted. The solution to the pollution problem lies in determining the 

 best way of handling the waste material. We camiot stop waste dis- 

 posal — we must learn to control it and perhaps handle it without hav- 

 ing to use large quantities of water for waste dilution. 



The Potomac Kiver, which is the source of water supply for the 

 Nation's Capital and other communities, has been polluted by the 

 municipal and industrial sewage discharged into the river and its 

 tributaries. Aquatic vegetation and fish camiot thrive in its polluted 

 water. Recreational activities such as swimming and boating bring 

 people into contact with polluted water, constituting a health hazard. 

 The prevention of future pollution and the control of the present pol- 

 lution are goals that can benefit all users of the Potomac. Steps have 

 already been taken to cut down or eliminate the discharge of raw sew- 

 age into the Potomac Eiver ; many cities now treat the sewage before 

 disposal. 



The estuary of the Potomac is narrow and deep and extends from 

 Chesapeake Bay upstream to Washington. The river in this estuary 

 receives pollution from other streams flowing directly into it and from 

 sewage of cities adjacent to the estuary. The large size of the estuary 

 combined with a back and forth movement of tidal surges prevent the 

 pollutants from discharging into the sea fast enough, and the pollut- 

 ants are therefore concentrated in the estuary, raising the tempera- 

 ture of the water and increasing the concentration of organic material. 

 Within a few years no raw sewage will be discharged into the Poto- 

 mac, but the problem of concentration of pollutants may still remain. 

 Perhaps it will be necessary to dispose of sewage without discharging 

 it into the river. Pumping sewage into gromid- water reservoirs has 

 been suggested as a pollution-abatement measure along the Potomac. 



