THE IRRIGATION AGE 245 



air and sunlight rapidly decompose any organic matter with which 

 they come in contact, by oxidizing it. For instance, sulfuretted hyd- 

 rogen, a gas most obnoxius to our sense of smell, is, when it once 

 comes in contact with the air, at once decomposed into water and 

 minute flakes of harmless white sulphur, which float away into 

 infinity. As the obnoxious part of common sewage consists almost 

 exclusively of organic matter, it stands to reason that it will be 

 quickly rendered harmless by those powerful disinfectants of nature, 

 if thoroughly exposed to them. 



What I have said ought to satisfy all fair-minded persons that the 

 using of sewage for irrigation is perfectly justifiable. But there is 

 another point, as important as this one, which has to be explained. 



It is claimed that some of the sewage, after it is used for irriga- 

 tion, may enter Mill Creek zanja. The gentlemen interested claim 

 that this can be easily avoided with care, as any superabundant 

 sewage may, at any time, be turned off on to the sewage farm. But 

 suppose some of it will enter the zanja. After all, it can be but very 

 little, and this little already greatly purified by its previous distribu- 

 tion over the land. 



And, indeed, I am at a loss to understand how this small amount 

 of sewage can hurt a stream of water which is already exposed to the 

 leakage from thousands of acres of land treated continuously with 

 natural as well as artificial fertilizers. For a long time the settlers 

 below have discarded the use of this water for domestic purposes. 



But to settle this matter, conclusively, let me explain what this 

 pollution really amounts to. 



Should any sewage enter the zanja it mixes at once with a large 

 body of water. The stream has considerable fall, rushes over a 

 pebbly bottom, and its waters are continuously revolved to the sur- 

 face, bringing them in contact with air and light Nature's disinfect- 

 ants. In a stream like that all organic matter must be quickly oxid- 

 ized. I will give an illustration how rapidly streams will purify 

 themselves. 



Nearly all the cities in the great Sacramento river basin, from 

 Red Bluff down, Oroville, Colusa, Yuba City, and so forth: almost all 

 the large settlements along the affluents of the Sacramento river dis- 

 charge their sewage into the respective streams. Further down tne 

 populous city of Marysville adds her quota. From there down the 

 Sacramento river is very sluggish, and offers but limited opportun- 

 ities to nature's disinfectants. Yet, during its twenty miles' course 

 from Marysville to Sacramento, the river has puriled itself so much 

 that the citizens of Sacramento prefer to drink the water from the 

 river to that from the deep wells at their disposal. And what is 

 more, the death rate of Sacramento has not increased during the last 

 twenty years, though the people have used the river water almost ex 



