340 WATER HYGIENE 
genic bacteria in water but indirectly it is concerned with nuisances 
which almost certainly result when a stream is made to carry too much 
waste matter. In America the question is being given some official 
attention by the Federal government and most States have statutes 
governing the pollution of streams. These have been reviewed by 
Montgomery and Phelps (1917). The United States Public Health 
Service has investigated the pollution and sanitary conditions of 
the Potomac watershed and a very complete report has been prepared 
by Cumming (1916). In this interesting sanitary survey it was found 
that the Potomac River “ even during the period of lowest stream flow 
the river in the area of heaviest pollution . . . has, at all times, suffi- 
cient oxygen available for the sewage now discharged into the river and 
enough to take care of that which will probably be added for several 
years to come.” Investigations are also being conducted on the Ohio 
river but the results are not available. 
TaBLe XXXITI 
SHOWING THE EXTENT OF SELF PURIFICATION IN THE ILLINOIS 
RIVER 
(After Jordan, 1900) 
Collecting Stations. Teance from Cplorine, Bacteria. Muniber of 
Bridgeport, Illinois............. 0 119.2 1,245,000 19 
Lockport...... 000.02 e eee eee ees 29 117.4 650,000 30 
Desplaines R. at Lockport.......) ......... 7.9 9,180 28 
0) b=) (er 33 104.8 486,000 | _ 28 
Kankakee River... ........20000) cece eeaee 3.4 5,000 28 
Morris. ........-. 02 ee eee eee ee 57 68.1 439,000 26 
Ottawa... cece ee eee 81 58.5 27,400 26 
Fox River at Ottawa............] cee. eee ee 5.0 6,510 29 
Big Vermillion at LaSalle........] ......... 61.2 7,970 30 
LaSalle... 0... eee eee eee 95 46.1 16,300 31 
Henry... 2... eee ce eee ee eee 123 44.2 11,200 29 
Averyville............. 0.0005. 159 40.9 3,660 30 
Wesley City... 0.0.0... eee eee 165 40.1 758,000 22 
Pekin... 0... eee eee eee 175 38 .4 492,000 29 
Havana. ...... cc eee cee eee 199 36.2 16,800 26 
Beardstown........-0 cece eevee 231 29.3 14,000 26 
Kempsville................005. 288 22.9 4,800 19 
Grafton. ... 0... cece eee 318 18.3 10,200 28 
Mississippi River at Grafton.....) ......... 2.8 7,600 29 
One of the most instructive cases of stream pollution is that of the 
Illinois River, which is made to carry the sewage of Chicago. The facts 
