Ill. Admin. Code tit. 35, § 302.408 - Temperature

a) For the South Fork of the South Branch of the Chicago River (Bubbly Creek), the temperature must not exceed 34 °C (93 °F) more than 5% of the time, or 37.8 °C (100 °F) at any time.
b) The temperature standards in subsections (c) through (i) will become applicable beginning July 1, 2018.
c) There must not be any abnormal temperature changes that may adversely affect aquatic life unless caused by natural conditions.
d) The normal daily and seasonal temperature fluctuations that existed before the addition of heat due to other than natural causes must be maintained.
e) The maximum temperature rise above natural temperatures must never exceed 2.8 °C (5 °F).
f) Water temperature at representative locations in the main river must never exceed the maximum limits in the applicable table in subsections (g), (h) and (i), during more than one percent of the hours in the 12-month period ending with any month. The water temperature must not exceed the maximum limits in the applicable table that follows by more than 1.7 °C (3.0 °F).
g) Water temperature in the Chicago Area Waterway System Aquatic Life Use A waters listed in 35 Ill. Adm. Code 303.235 must not exceed the limits in the following table in compliance with subsection (f):

Months

Daily Maximum

(° C)

(° F)

January

16

60

February

16

60

March

16

60

April

32

90

May

32

90

June

32

90

July

32

90

August

32

90

September

32

90

October

32

90

November

32

90

December

16

60

h) Water temperature in the Chicago Area Waterway System and Brandon Pool Aquatic Life Use B waters listed in 35 Ill. Adm. Code 303.240 must not exceed the limits in the following table in compliance with subsection (f):

Months

Daily Maximum

(° C)

(° F)

January

16

60

February

16

60

March

16

60

April

32

90

May

32

90

June

32

90

July

32

90

August

32

90

September

32

90

October

32

90

November

32

90

December

16

60

i) Water temperature for the Upper Dresden Island Pool Aquatic Life Use waters, as defined in 35 Ill. Adm. Code 303.230, must not exceed the limits in the following table in compliance with subsection (f):

Months

Daily Maximum

(° C)

(° F)

January

16

60

February

16

60

March

16

60

April

32

90

May

32

90

June

32

90

July

32

90

August

32

90

September

32

90

October

32

90

November

32

90

December

16

60

Notes

Ill. Admin. Code tit. 35, § 302.408
Amended at 39 Ill. Reg. 9388, effective 7/1/2015 Amended at 47 Ill. Reg. 4437, effective 3/23/2023

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