Section 303.100  Scope and Applicability

Part 303 contains water use designations that determine which set of Part 302 water quality standards apply for a given body of water.  Part 303 also contains site-specific water quality standards.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.101  Multiple Designations

Unless otherwise expressly stated, waters designated for specific uses must meet the most restrictive standards listed in 35 Ill. Adm. Code 302 for any specified use, in addition to meeting the general standards of Subpart B of 35 Ill. Adm. Code 302.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.102  Rulemaking Required (Repealed)

(Source:  Repealed at 35 Ill. Reg. 15078, effective August 23, 2011)

Section 303.200  Scope and Applicability

Subpart B contains general water use designations.  These Sections, together with the specific designations of Subpart C, determine which set of water quality standards of 35 Ill. Adm. Code 302 applies to a given body of water.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.201  General Use Waters

Except as otherwise specifically provided, all waters of the State must meet the general use standards of Subpart B of 35 Ill. Adm. Code 302.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.202  Public and Food Processing Water Supplies

Except as otherwise specifically provided and in addition to the general use standards of Subpart B of 35 Ill. Adm. Code 302, waters of the State must meet the public and food processing water supply standards of Subpart C of 35 Ill. Adm. Code 302, at any point where water is withdrawn for treatment and distribution as a potable supply or for food processing.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.203  Underground Waters

35 Ill. Adm. Code 302.Subparts B and C do not apply to underground waters, except as provided at 35 Ill. Adm. Code 620.450(b).

(Source:  Amended at 16 Ill. Reg. 14684, effective September 10, 1992)

Section 303.204  Chicago Area Waterway System and Lower Des Plaines River

The Chicago Area Waterway System and Lower Des Plaines River Waters are designated to protect for primary contact recreation, incidental contact or non-contact recreational uses (except where designated as non-recreational waters), commercial activity (including navigation and industrial water supply uses), and the highest quality aquatic life and wildlife attainable, limited only by the physical condition of these waters and hydrologic modifications to these waters.  Except for the Chicago River, these waters are required to meet the standards contained in 35 Ill. Adm. Code 302, Subpart D, but are not required to meet the general use standards or the public and food processing water supply standards of 35 Ill. Adm. Code 302, Subpart B and C, except that the waters designated as Primary Contact Recreation Waters in Section 303.220 must meet the numeric water quality standard for fecal coliform bacteria applicable to protected waters in 35 Ill. Adm. Code 302.209. Designated recreational uses and aquatic life use for each segment of the Chicago Area Waterway System and Lower Des Plaines River are identified in this Subpart.  The Chicago River must meet the general use standards of 35 Ill. Adm. Code 302, Subpart B, including the numeric water quality standard for fecal coliform bacteria applicable to protected waters in 35 Ill. Adm. Code 302.209.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.205  Outstanding Resource Waters

An Outstanding Resource Water (ORW) is a surface water body or water body segment that is of exceptional ecological or recreational significance and must be designated by the Board under 35 Ill. Adm. Code 102.Subpart H.

a)         Outstanding Resource Waters (ORW) must be listed in Section 303.206. In addition to all other applicable use designations and water quality standards contained in this Subtitle, an ORW is subject to the antidegradation provision of 35 Ill. Adm. Code 302.105(b).

b)         A petition to designate a surface water body or water body segment as an ORW must be submitted to the Illinois Pollution Control Board under the procedural rules in 35 Ill. Adm. Code 102.Subpart H.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.206  List of Outstanding Resource Waters

The Board has not designated any Outstanding Resource Waters under 35 Ill. Adm. Code 102.Subpart H.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.220  Primary Contact Recreation Waters

The following waters are designated as Primary Contact Recreation Waters and must be protected for Primary Contact Recreation uses as defined in 35 Ill. Adm. Code 301.323. These

waters must meet the numeric water quality standard for fecal coliform bacteria applicable to

protected waters in 35 Ill. Adm. Code 302.209.

a)         Lower North Shore Channel from North Side Water Reclamation Plant to confluence with North Branch of the Chicago River;

b)         North Branch of the Chicago River from its confluence with North Shore Channel to its confluence with South Branch of the Chicago River and Chicago River;

c)         Chicago River;

d)         South Branch of the Chicago River;

e)         Little Calumet River from its confluence with Calumet River and Grand Calumet River to its confluence with Cal-Sag Channel; and

f)         Cal-Sag Channel.

(Source:  Amended at 38 Ill. Reg. 5517, effective February 13, 2014)

Section 303.225  Incidental Contact Recreation Waters

The following waters are designated as Incidental Contact Recreation Waters and must protect for incidental contact recreational uses as defined in 35 Ill. Adm. Code 301.282.

a)         Upper North Shore Channel from Wilmette Pumping Station to North Side Water Reclamation Plant;

b)         South Fork of the South Branch of the Chicago River (Bubbly Creek);

c)         Chicago Sanitary and Ship Canal from its confluence with the South Branch of the Chicago River to its confluence with Calumet-Sag Channel;

d)         Calumet River from Torrence Avenue to its confluence with Grand Calumet River and Little Calumet River;

e)         Lake Calumet;

f)         Lake Calumet Connecting Channel;

g)         Grand Calumet River;

h)         Lower Des Plaines River from the Brandon Road Lock and Dam to the Interstate 55 Bridge.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.227  Non-Contact Recreation Waters and Non-Recreational Waters

a)         Non-Contact Recreation. Calumet River from Lake Michigan to Torrence Avenue is designated as a Non-Contact Recreation Water and must protect for non-contact recreational uses as defined in 35 Ill. Adm. Code 301.324.

b)         The following waters are designated as Non-Recreational waters as defined in 35 Ill. Adm. Code 301.324.

1)         Chicago Sanitary and Ship Canal from its confluence with the Calumet-Sag Channel to its confluence with Des Plaines River; and

2)         Lower Des Plaines River from its confluence with Chicago Sanitary and Ship Canal to the Brandon Road Lock and Dam. 

(Source:  Added at 35 Ill. Reg. 15078, effective August 23, 2011)

Section 303.230  Upper Dresden Island Pool Aquatic Life Use Waters

Upper Dresden Island Pool Aquatic Life Use Waters

a)         Lower Des Plaines River from the Brandon Road Lock and Dam to the Interstate 55 Bridge is designated as the Upper Dresden Island Pool Aquatic Life Use.  These waters are capable of maintaining, and must have quality sufficient to protect, aquatic-life populations consisting of individuals of tolerant, intermediately tolerant, and intolerant types that are adaptive to the unique flow conditions necessary to maintain navigational use and upstream flood control functions of the waterway system.  The aquatic life may include largemouth bass, bluntnose minnow, channel catfish, orangespotted sunfish, smallmouth bass, shorthead redhorse, and spottail shiner.

b)         Upper Dresden Island Pool Aquatic Life Use Waters must meet the water quality standards of 35 Ill. Adm. Code 302 Subpart D.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.235  Chicago Area Waterway System Aquatic Life Use A Waters

a)         Waters designated as Chicago Area Waterway System Aquatic Life Use A Waters are capable of maintaining, and must have quality sufficient to protect, aquatic-life populations predominated by individuals of tolerant and intermediately tolerant types that are adaptive to the unique physical conditions, flow patterns, and operational controls necessary to maintain navigational use, flood control, and drainage functions of the waterway system.  The aquatic life may include fish species, such as channel catfish, largemouth bass, bluegill, black crappie, spotfin shiner, orangespotted sunfish, common carp, and goldfish.

b)         Waters designated as Chicago Area Waterway System Aquatic Life Use A Waters are not capable of attaining an aquatic life use consistent with the section 101(a)(2) of the Clean Water Act goal (33 U.S.C. 1251(a)(2)).

c)         The following waters are designated as Chicago Area Waterway System Aquatic Life Use A Waters and must meet the water quality standards of 35 Ill. Adm. Code 302. Subpart D:

1)         Upper North Shore Channel from Wilmette Pumping Station to North Side Water Reclamation Plant;

2)         Lower North Shore Channel from North Side Water Reclamation Plant to its confluence with the North Branch of the Chicago River;

3)         North Branch of the Chicago River from its confluence with North Shore Channel to its confluence with South Branch of the Chicago River and Chicago River;

4)         South Branch of the Chicago River;

5)         Calumet-Sag Channel;

6)         Calumet River from Lake Michigan to its confluence with Grand Calumet River and Little Calumet River;

7)         Little Calumet River from its confluence with Calumet River and Grand Calumet River to its confluence with Calumet-Sag Channel;

8)         Grand Calumet River;

9)         Lake Calumet; and

10)         Lake Calumet Connecting Channel.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.240  Chicago Area Waterway System and Brandon Pool Aquatic Life Use B Waters

a)         Waters designated as Chicago Area Waterway System and Brandon Pool Aquatic Life Use B Waters are capable of maintaining, and must have quality sufficient to protect, aquatic life populations predominated by individuals of tolerant types that are adaptive to unique physical conditions and modifications of long duration, including artificially constructed channels consisting of vertical sheet-pile, concrete and rip-rap walls designed to support commercial navigation, flood control, and drainage functions in deep-draft, steep-walled shipping channels.  The aquatic life may include fish species, such as common carp, golden shiner, bluntnose minnow, yellow bullhead, and green sunfish.

b)         Waters designated as Chicago Area Waterway System and Brandon Pool Aquatic Life Use B Waters are not capable of attaining an aquatic life use consistent with the goal of section 101(a)(2) of the Clean Water Act (33 U.S.C. 1251(a)(2)).

c)         The following waters are designated as Chicago Area Waterway System and Brandon Pool Aquatic Life Use B Waters and must meet the water quality standards of 35 Ill. Adm. Code 302 Subpart D:

1)         Chicago Sanitary and Ship Canal; and

2)         Lower Des Plaines River from its confluence with Chicago Sanitary and Ship Canal to the Brandon Road Lock and Dam (Brandon Pool).

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.300  Scope and Applicability

Subpart C contains specific use designations that determine which set of water quality standards of 35 Ill. Adm. Code 302 applies to a given water.  In addition, Subpart C contains water quality standards applicable to specified waters. Nonspecific designations are in Subpart B.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.301  Organization

Subpart C is arranged by river basin as follows:

Section 303.311  Ohio River Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e) the water temperature at representative locations in the main river of the Ohio River must not exceed the maximum limits in the following table during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.312  Waters Receiving Fluorspar Mine Drainage (Repealed)

(Source:  Repealed at 36 Ill. Reg. 18898, effective December 12, 2012)

Section 303.321  Wabash River Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e), the water temperature at representative locations in the main river of the Wabash River and its interstate tributaries must not exceed the maximum limits in the following table during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.322  Unnamed Tributary of the Vermilion River (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.323  Sugar Creek and Its Unnamed Tributary

a)         This Section applies only to Sugar Creek and its unnamed tributary from the point at which Marathon Oil Company's outfall 001 discharges into the unnamed tributary to the confluence of Sugar Creek and the Wabash River.

b)         35 Ill. Adm. Code 304.105 does not apply to total dissolved solids and chlorides discharged by Marathon Oil Company's outfall 001 if both of the following conditions are met:

1)         Effluent from Marathon Oil Company's outfall 001 does not exceed either 3,000 mg/L total dissolved solids or 1,000 mg/L chlorides, and

2)         The water in the unnamed tributary does not exceed 2,000 mg/L total dissolved solids or 750 mg/L chlorides.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.326  Unnamed Tributary of Salt Creek, Salt Creek, and Little Wabash River

The fluoride general use water quality standard of 35 Ill. Adm. Code 302.208(g) does not apply to the waters of the State from the point of discharge of the POTW located at 903 E. Eichie Avenue in Effingham, Illinois, owned by the City of Effingham, to an unnamed tributary of Salt Creek, located in Effingham County, T8N, R6E, Sec. 28, Lat:  39°06’24”, Long:  88°31’55”, to the confluence of the unnamed tributary with Salt Creek; to the confluence of Salt Creek with the Little Wabash River; to the confluence of Buck Creek and the Little Wabash River.  Fluoride levels in these waters must meet a water quality standard for fluoride specified in this Section.

a)         From the point of discharge of the City of Effingham POTW to the unnamed tributary to the confluence of the unnamed tributary with Salt Creek and from the confluence of the unnamed tributary with Salt Creek to the confluence of Salt Creek with the Little Wabash River, the fluoride water quality standard is 5.0 mg/L.

b)         From the confluence of Salt Creek with the Little Wabash River to monitoring station C-19 located on the Little Wabash River approximately 2.8 miles downstream of Louisville, Illinois, the fluoride water quality standard is 3.2 mg/L.

c)         From monitoring station C-19 located on a point on the Little Wabash River approximately 2.8 miles downstream of Louisville, Illinois to the confluence of Buck Creek and the Little Wabash River, a point on the Little Wabash River located approximately 9.8 miles downstream of Louisville, Illinois, the fluoride water quality standard is 2.0 mg/L.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.331  Mississippi River North Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e) the water temperature at representative locations in the main river of the Mississippi River from the Wisconsin border to the Rock River must not exceed the maximum limits in the following table during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.341  Mississippi River North Central Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e), the water temperature at representative locations in the main river of the Mississippi River in the indicated locations must not exceed the maximum limits in the following tables during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

a)         In the Mississippi River from the Rock River to the Iowa/Missouri border:

b)         In the Mississippi River from the Iowa/Missouri border to the Illinois River:

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.351  Mississippi River South Central Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e), the water temperature at representative locations in the main river of the Mississippi River in the indicated locations must not exceed the maximum limits in the following tables during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

a)         In the Mississippi River from the Illinois River to Alton Lock and Dam:

b)         In the Mississippi River from Alton Lock and Dam to the Kaskaskia River:

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.352  Unnamed Tributary of Wood River Creek

a)         This section applies to the unnamed tributary of Wood River Creek that enters Wood River Creek 4700 feet above the confluence of Wood River Creek with the Mississippi River from a point 450 feet above the confluence of the unnamed tributary and Wood River Creek to the confluence, and in Wood River Creek from the confluence to the confluence of Wood River Creek and the Mississippi River.

b)         The waters must meet a boron standard of 15 mg/L instead of the boron standard of 35 Ill. Adm. Code 302.208:

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.353  Schoenberger Creek; Unnamed Tributary of Cahokia Canal

a)         This rule applies to:

1)         The final 1500 feet of Schoenberger Creek starting immediately south of the Baltimore and Ohio main tracks and running north to an unnamed tributary of the Cahokia Canal; and

2)         The unnamed tributary from its confluence with Schoenberger Creek as it runs west and northwest for a distance of 8000 feet to its confluence with the Cahokia Canal.

b)         The standard for iron (dissolved) in 35 Ill. Adm. Code 302.208 does not apply to these waters.  Instead, the waters must not exceed an iron (total) concentration of 20 mg/L.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.361  Mississippi River South Temperature

Instead of the standards of 35 Ill. Adm. Code 302.211(e), the water temperature at representative locations in the main river of the Mississippi River from the Kaskaskia River to the Ohio River must not exceed the maximum limits in the following table during more than 1% of the hours in the 12-month period ending with any month.  The water temperature at these locations must not at any time exceed the maximum limits in the following table by more than 1.7 ºC (3 ºF).

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.400  Bankline Disposal Along the Illinois Waterway/River

a)         The U.S. Department of the Army, Corps of Engineers, may bankline dispose of sediment generated during maintenance dredging operations on the Illinois Waterway/River between river miles 80.2 and 291 if:

1)         Less than 10% of representative samples from a proposed dredge cut are composed of fine-grained material, where a material is fine-grained if more than 20% of the sample passes a #230 sieve; or

2)         The SSTFATE model indicates that applicable water quality standards will be met at the perimeter of a temporary area of allowed dilution having a surface area no larger than 48,000 square feet, and not exceeding either 1,000 feet in length or 150 feet in width; and

3)         The U.S. Department of the Army, Corps of Engineers, holds a Water Quality Certification for its dredging operations from the Illinois Environmental Protection Agency pursuant to Section 401 of the federal Clean Water Act, 33 U.S.C. § 1341 (1988).

b)         When the provisions of subsection (a) are met, 35 Ill. Adm. Code 304.105, does not apply to bankline disposal by the U.S. Department of the Army, Corps of Engineers, but only as 35 Ill. Adm. Code 304.105 pertains to the offensive conditions standard of 35 Ill. Adm. Code 302.203, the dissolved oxygen standard of 35 Ill. Adm. Code 302.206, the total lead, total zinc, mercury, and total copper standards of 35 Ill. Adm. Code 302.208, and the ammonia nitrogen and un-ionized ammonia nitrogen standards of 35 Ill. Adm. Code 302.212.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.410 Chronic Nickel Water Quality Standard for Segment of the Sangamon River

The general use chronic water quality standard for dissolved nickel contained in 35 Ill. Adm. Code 302.208(e) does not apply to the segment of the Sangamon River that receives discharges from the Sanitary District of Decatur's Main Sewage Treatment Plant, from that facility's Outfall 001 located at 39° 49' 56" North Latitude, 89° 0' 7" West Longitude, to the point of the confluence of the Sangamon River with the South Fork of the Sangamon River near Riverton. Instead, waters in this segment of the Sangamon River must meet a chronic water quality standard for dissolved nickel as follows:

Chronic Dissolved Nickel Standard (µg/L) = exp[A+Bln(H)] x 0.997* x WER

where:

A = -2.286,

B = 0.8460,

ln(H) = natural logarithm of Hardness, and

WER (Water Effect Ratio) = 2.50.

*conversion factor multiplier for dissolved metals

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.430  Unnamed Tributary to Dutch Creek (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.431  Long Point Slough and Its Unnamed Tributary (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.441  Secondary Contact Waters (Repealed)

(Source:  Repealed at 35 Ill. Reg. 15078, effective August 23, 2011)

Section 303.442  Waters Not Designated for Public Water Supply

The following waters are not required to meet the public and food processing water supply standards of 35 Ill. Adm. Code 302.Subpart C, even where designated as general use waters:

a)         The Chicago River

b)         The Little Calumet River.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.443  Lake Michigan Basin

The waters of the Lake Michigan Basin must meet the Lake Michigan Basin water quality standards of 35 Ill. Adm. Code 302 Subpart E.  Lake Michigan Basin waters under Illinois jurisdiction consist of the following:

a)         The Open Waters of Lake Michigan means all of the waters within Lake Michigan in Illinois jurisdiction lakeward from a line drawn across the mouth of tributaries to Lake Michigan, but not including waters enclosed by constructed breakwaters;

b)         Lake Michigan harbors and waters (as defined in 35 Ill. Adm. Code 301.440) within Illinois jurisdiction within breakwaters, and waters tributary to Lake Michigan including streams, sloughs and other watercourses not named elsewhere in this Part; and

c)         The Chicago River, the North Shore Channel, and the Calumet River are not part of the Lake Michigan Basin.

(Source:  Amended at 22 Ill. Reg. 1403, effective December 24, 1997)

Section 303.444  Salt Creek, Higgins Creek, West Branch of the DuPage River, Des Plaines River

The General Use chronic water quality standard for cyanide in 35 Ill. Adm. Code 302.208 does not apply to Salt Creek, Higgins Creek, the West Branch of the DuPage River, and the Des Plaines River in Cook County, Illinois.  Instead, for these waters the chronic cyanide standard is 10 μg/L.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.445  Total Dissolved Solids Water Quality Standard for the Lower Des Plaines River (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.446  Boron Water Quality Standard for Segments of the Sangamon River and the Illinois River

The general use water quality standard for boron in 35 Ill. Adm. Code 302.208(g) does not apply to segments of the Sangamon River and the Illinois River described below that receive discharge from Outfall 007 of the Spring Creek Sewage Treatment Plant located at 3017 North 8^th Street, Springfield, Illinois, owned by the Springfield Metro Sanitary District.  The boron level in those river segments must meet the following water quality standard for boron:  11.0 mg/L in the Sangamon River from Outfall 007 (Latitude:  39° 51' 37.234" North, Longitude:  89° 38' 30.082" West) to 182 yards downstream from the confluence of Spring Creek with the Sangamon River (Latitude:  39° 51' 42.595" North, Longitude:  89° 38' 30.089" West);

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.447  Unnamed Tributary of the South Branch Edwards River and South Branch Edwards River (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.448  Mud Run Creek (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.449  Chicago Sanitary and Ship Canal

The numeric water quality standards for chloride and Total Dissolved Solids in 35 Ill. Adm. Code 302.407(g) do not apply to the Chicago Sanitary and Ship Canal from December 1 through April 30 for the protection of aquatic organisms.  Chloride levels in these waters must meet the numeric water quality standards of 620 mg/L as a chronic water quality standard and 990 mg/L as an acute water quality standard from December 1 through April 30.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.500  Scope and Applicability

Subpart D contains site-specific water quality-based thermal discharge standards. These are now determined without rulemaking under 35 Ill. Adm. Code 302.211 and 35 Ill. Adm. Code 106.

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.502  Lake Sangchris Thermal Discharges

The thermal discharge to Lake Sangchris must meet the following standards and conditions:  The effluent temperature must not exceed 37 ºC (99 ºF) during more than 7% of the hours in the 12-month period ending with any month and must not exceed 44 ºC (111 ºF).

(Source:  Amended at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.APPENDIX A   References to Previous Rules (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)

Section 303.APPENDIX B   Sources of Codified Section (Repealed)

(Source:  Repealed at 47 Ill. Reg. 4575, effective March 23, 2023)