Table 3.

Estimated Population of Four Communities in Southern Illinois Based on a Load of Ammoniacal Nitrogen in Raw Wastewater

communities	census estimationa	NH4–N (mg/L)b	NH4–N-based populationb
C1	7882	23.2 ± 1.9	9283 ± 397
C2	17 620	21.1 ± 2.1	19,597 ± 799
C3	20 000c	10.3 ± 0.5	16,253 ± 976
C4	2188	10.8 ± 0.9	2980 ± 239

^aCensus annual estimate of the resident population by the U.S. Census Bureau in 2018.

^bAverage ± standard error.

^cWWTP operator’s estimation.