Illinois Administrative Code
Title 35 - ENVIRONMENTAL PROTECTION
Part 302 - WATER QUALITY STANDARDS
Subpart D - CHICAGO AREA WATERWAY SYSTEM AND LOWER DES PLAINES RIVER WATER QUALITY STANDARDS AND INDIGENOUS AQUATIC LIFE STANDARDS
Section 302.412 - Total Ammonia Nitrogen
Current through Register Vol. 48, No. 12, March 22, 2024
a) This Section does not apply to the South Fork of the South Branch of the Chicago River (Bubbly Creek).
b) For the Chicago Area Waterway System and the Lower Des Plaines River described in 35 Ill. Adm. Code 303.204 and listed in 35 Ill. Adm. Code 303.220 through 303.240, total ammonia nitrogen must in no case exceed 15 mg/L.
c) The total ammonia nitrogen acute, chronic, and sub-chronic standards are determined in compliance with the equations in subsections (c)(1) and (c)(2). Attainment of each standard must be determined in compliance with subsections (d) and (e) in mg/L.
where:
T |
= |
Water Temperature, degrees Celsius |
Where:
T |
= |
Water Temperature, degrees Celsius |
d) Attainment of the Total Ammonia Nitrogen Water Quality Standards
e) The water quality standard for each water body must be calculated based on the temperature and pH of the water body measured at the time of each ammonia sample. The concentration of total ammonia in each sample must be divided by the calculated water quality standard for the sample to determine a quotient. The water quality standard is attained if the mean of the sample quotients is less than or equal to one for the duration of the averaging period.
f) The Early Life Stage Present period occurs from March through October. All other periods are subject to the Early Life Stage Absent period, except that waters listed in 35 Ill. Adm. Code 303.240 are not subject to Early Life Stage Present ammonia limits at any time.
BOARD NOTE: Acute and chronic standard concentrations for total ammonia nitrogen (in mg/L) for different combinations of pH and temperature are shown in Appendix C.