200 



waters a volume of sewage equal to the pumpage, though their 

 imperfectly developed systems of drainage, combined with the 

 surface run-off, carry some sewage to the stream. 



Population and Pumpage in Cities without Sewage Systems. 



City 



Population in 1890 



Daily Pumpage 

 in gal. 



Remarks. 



Illinois 









Batavia 



3.543 



2,500 



1,500 — 3,500 gallons. 



Braidwood 



4,641 



5,500 



1,000 — 10,000 " 



Chenoa 



1,226 



20,000 





Delavan 



1,176 



50,000 





Dundee 



2,073 



70,000 





Earlville 



1,058 



25,500 





Elmwood 



1,548 



19,000 



7,000—31,000 gallons, 



El Paso 



i,353 



27,500 



25,000 — 30,000 " 



Fairbury 



2,324 



71,500 



53,000—90,000 " 



Forrest 



1,021 



8,442 





Geneva 



1,692 



40,000 



Pumpage estimated. 



Lacon 



1,649 



15,000 





Lexington 



1,187 



60,000 





Lockport 



2,449 



44,500 





Minonk 



2,316 



109,689 





Momence 



1,635 



250,000 





Morris 



3,653 



54,795 





Piano 



1,825 



3i,5 o 





Princeton 



3,396 



650,000 





Spring Valley 



3,837 



55,ooo 





Washington 



1,301 



100,000 





Wenona 



1,053 



23,000 



21,000 — 25,000 gallons. 



West Chicago 



1,506 



20,000 





Total 



47,562 



1,753,426 



Total pumpage, 2.8 cu. ft. 

 per sec. 



The principal sources of the sewage contributed to the 

 Illinois River above Havana are Chicago, Peoria, and the 

 smaller cities within the drainage basin. The amounts 

 contributed by each are approximately 520,275,109, 5,000,000, 

 and 16,007,378 gallons respectively per day. The total amount 

 of 542,282,487 gallons per day or 838.7 cubic feet per second is 

 about 8 per cent, of the average flow of the river at Havana and 

 exceeds by 40 per cent, the estimated low-water flow at Cop- 

 peras Creek dam, eighteen miles above our plankton station. 

 In 1890 the population of the two larger cities and the total of 

 the remaining smaller ones was respectively 849,850, 41,024, 

 and 188,817, a total of 1,079,691, 250,003 having been deducted 



