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000388 Pollution Problems and Future Control Needs Municipal Wastes Household and other wastes from cities and towns have long been major pollutants to streams. At first the wastes were hauled and dumped into streambeds where high flows washed them away. The first sewage collection systems instal led in the 1890's discharged the wastes directly into watercourses untreated. As of July 1, 1969, three towns in the State with a combined population of 1,785 sti II used this means of waste disposal. In addition, Lincoln and Omaha have areas served by combina- tion storm and sanitary sewers. During heavy rainstorms or snowmelts much of the runoff, including sewage, bypasses the treatment plants and flows untreated into streams. Forty-six communities with a combined population of sl ightlY over 418,000 provide primary treatment of their wastes before discharging the effluent into watercourses. This treatment includes grit removal, skimming, and settling basins to remove the settleable and floatable materials from the sewage. Such treatment removes only a limited amount of the biodegradable materials and the effluent has a high oxygen requirement. In many places, immediately downstream from the sewage treatment plant outlets, the natural oxidation of such materials reduces the amount of avai lable oxygen in the water to less than that required to susta I n fish life. Three hundred forty communities with a total population sliqhtly over 528,000 are providing secondary treatment for their sewage. This is a biological or chemic~1 process to remove pollutants. Properly operated efficient plants remove 85 percent or more of both BOD (Bio- chemical Oxygen Demand) and suspended solids. Seventy-eight sma I I communities with a combined population of about 13,600 do not have sewage collection systems. Pollution problems arising from the cesspools and septic tanks used to treat individual household wastes are mainly local in extent. Table 23 contains a summary of an inventory of municipal sewage treatment faci lities. Detai led reports showing the types of treatment provided and treatment needs of communities by river basins are contained in Attachment 7. This inventory is believed correct to July 1, 1969. Since new systems are continually being instal led and old systems replaced or Improved, the summary tables on sewage treatment are soon outdated. In add1tlon to sewage collection systems serving municipalities, there are seventeen federal instal lations In the State with separate surface discharges. These plants process about 1.25 mi I lion gal Ions of sewage dai Iy, an amount equal to that produced by a city of 20,000 people. All of these instal lations provide secondary treatment at present or are constructing additional faci Ilties to provide such treatment. Plants of two federal instal lations are in need of remodeling or enlargement. 52