every 10 years and to persist for at least 7 days, the dissolved oxygen 

 levels under existing waste loads would be below the Illinois standard 

 of 5 mg/1 in Marseilles, Starved Rock, and Peoria Pools (Butts, et al., 

 1975). Moreover, the oxygen levels would be between and 1 mg/1 in 

 substantial portions of these pools. Such low oxygen levels would dras- 

 tically reduce the fish populations in the river. In order to meet the 

 State dissolved oxygen standard in the Upper Illinois River during 7-day 

 10-year low-flow conditions, Butts et al. (1975) estimate that 97.5 per- 

 cent of the carbonaceous biochemical oxygen demand must be removed from 

 waste at the West Southwest treatment plant of the Metropolitan Sanitary 

 District of Greater Chicago. Moreover, all other carbonaceous dis- 

 charges between the Lockport Dam and the Kankakee River must be reduced 

 50 percent, and 98 percent of the nitrogenous waste load above mile 273 

 must be removed. 



Some steps are planned, or have already been taken, to reduce waste 

 loads in the upper river. In 1971, the Chicago Metropolitan Sanitary 

 District began a large-scale sludge recycling project near the Illinois 

 River at St. David. In 1974, the district began aerating a section of 

 the Chicago Sanitary and Ship Canal, and more of the canal will be 

 aerated in succeeding years. In the future, all Chicago storm waters 

 probably will be captured and stored in a deep tunnel under Chicago, 

 instead of discharged to the canal, and will be treated before being 

 released to the canal. Advanced waste treatment plants should be cap- 

 able of removing the ammonia that now exerts an oxygen demand as far as 

 140 miles down river. All of these improvements in waste treatment will 

 certainly have a beneficial impact on the aquatic life in the river by 

 reducing the oxygen demand on the river and by improving oxygen levels 

 during critical low-flow periods. Waste treatment probably will also be 

 improved in the Pekin-Peoria metropolitan area. 

 Proposed channel improvements 



After measuring sediment oxygen demand in the Upper Illinois River 

 under both disturbed and quiescent conditions, Butts (1974) concluded 

 that improved waste treatment alone would not greatly restore the 

 aquatic ecology of the upper river: 



hS 



