§302.535. Ammonia Nitrogen

The Open Waters of Lake Michigan as defined in Section 302.501 must not exceed 0.02 mg/L total ammonia (as N).  The remaining waters of the Lake Michigan Basin are subject to the following:

 

a)         Total ammonia nitrogen (as N) must in no case exceed 15 mg/L.

 

b)         Un-ionized ammonia nitrogen (as N) must not exceed the acute and chronic standards given below subject to the provisions of Section 302.208(a) and (b):

 

1)         From April through October, the Acute Standard (AS) must be 0.33 mg/L and the chronic standard (CS) must be 0.057 mg/L.

 

2)         From November through March, the AS must be 0.14 mg/L and the CS must be 0.025 mg/L.

 

c)         For this Section, the concentration of un-ionized ammonia nitrogen as N and total ammonia as N must be computed according to the following equations:

 

U	=	N
		[0.94412(1 + 10x) + 0.0559]

 

and N = U[0.94412(1 + 10^x) + 0.0559]

 

Where:

 

X	=	0.09018	+	2729.92	-pH
				(T + 273.16)
U	=	Concentration of un-ionized ammonia as N in mg/L
N	=	Concentration of ammonia nitrogen as N in mg/L
T	=	Temperature in degrees Celsius.

 

(Source:  Amended at 47 Ill. Reg. 4437, effective March 23, 2023)