314 CMR, § 4.05

Current through Register 1536, December 6, 2024

Section 4.05 - Classes and Criteria

(1)Classes and Uses. The surface waters of the Commonwealth shall be segmented and each segment assigned to one of the Classes listed in 314 CMR 4.05(3) and (4). Each class is identified by the most sensitive, and therefore governing, water uses to be achieved and protected. Surface waters may be suitable for other beneficial uses, but shall be regulated by the Department to protect and enhance the existing and designated uses. In accordance with 314 CMR 4.03(4), the Department may designate a partial use subcategory for these Classes. A partial use designation may be appropriate where waters are impacted by combined sewer overflows or stormwater discharges. Partial use is described in 314 CMR 4.06(1)(d)11.

(2)Criteria.

(a) Minimum criteria for each class of surface water are listed in 314 CMR 4.05(3) and (4). Additional minimum criteria for all surface waters are listed in 314 CMR 4.05(5). In cases where fresh water and coastal and marine waters mix, 314 CMR 4.05(6) establishes whether fresh water or coastal and marine water aquatic life criteria apply. Provided that all existing and designated uses are protected, the Department may establish site-specific criteria as alternative minimum criteria. Site-specific numerical criteria also may supplement any of the narrative criteria in 314 CMR 4.00. Site-specific criteria are set forth in and pursuant to 314 CMR 4.05(7). Should the Department develop site-specific numerical criteria for any pollutant that is the primary cause of nonattainment of any criteria in 314 CMR 4.00, the Department may determine that such site-specific criteria supersede other criteria in 314 CMR 4.00. The Department may establish site-specific criteria for a segment or segments of a water, for an entire water, or for a group of waters with similar physical, chemical or biological qualities. The Department may establish site-specific hydrologic conditions at which criteria are applied. The Department will adopt any such site-specific criteria as revisions to 314 CMR 4.00 in accordance with M.G.L. c. 30A.

(b) Criteria for segments designated for partial use in 314 CMR 4.06 shall be site-specific but, to the maximum extent feasible, shall be the same as the criteria assigned to the Class. For segments so designated because of the impacts of CSO or stormwater discharges, criteria may depart from the criteria assigned to the Class only to the extent necessary to accommodate the technology-based treatment limitations of the CSO or stormwater discharges.

(3)Inland Water Classes.

(a)Class A. Those Inland Waters so designated pursuant to 314 CMR 4.06; including, without limitation, 314 CMR 4.06(1)(d)1. and (4) as public water supplies and their tributaries; certain wetlands designated in 314 CMR 4.06(2); certain reservoirs designated in 314 CMR 4.06(3); and certain surface waters designated in 314 CMR 4.06(6)(b). They are designated as excellent habitat for fish, other aquatic life and wildlife, including for their reproduction, migration, growth and other critical functions, and for primary and secondary contact recreation, even if not allowed. These waters shall have excellent aesthetic value. These waters are protected as Outstanding Resource Waters.

1.Dissolved Oxygen. Shall not be less than 6.0 mg/L in cold water fisheries and not less than 5.0 mg/L in warm water fisheries. Where natural background conditions are lower, DO shall not be less than natural background conditions. Natural seasonal and daily variations that are necessary to protect existing and designated uses shall be maintained.

2.Temperature.

b. natural seasonal and daily variations that are necessary to protect existing and designated uses shall be maintained. There shall be no changes from natural background conditions that would impair any use assigned to this Class, including those conditions necessary to protect normal species diversity, successful migration, reproductive functions or growth of aquatic organisms.

3.pH. Shall be in the range of 6.5 through 8.5 standard units and not more than 0.2 units outside of the natural background range. There shall be no change from natural background conditions that would impair any use assigned to this Class.

4.Bacteria.

a. Waters designated for shell fishing shall not exceed a fecal coliform median or geometric mean MPN of 88 organisms per 100 mL, nor shall more than 10% of the samples exceed an MPN of 260 per 100 mL or other values of equivalent protection based on sampling and analytical methods used by the Massachusetts Division of Marine Fisheries and approved by the National Shellfish Sanitation Program in the latest revision of the Guide For The Control of Molluscan Shellfish (more stringent regulations may apply, see314 CMR 4.06(1)(d)5.); and

b. For protection of primary contact recreation, surface waters shall meet the minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)2. and 3.

5.Solids. These waters shall be free from floating, suspended and settleable solids in concentrations or combinations that would impair any use assigned to this class, that would cause aesthetically objectionable conditions, or that would impair the benthic biota or degrade the chemical composition of the bottom.

6.Color and Turbidity. These waters shall be free from color and turbidity in concentrations or combinations that are aesthetically objectionable or would impair any use assigned to this class.

7.Oil and Grease. These waters shall be free from oil, grease and petrochemicals that produce a visible film on the surface of the water, impart an oily taste to the water or an oily or other undesirable taste to the edible portions of aquatic life, coat the banks or bottom of the water course, or are deleterious or become toxic to aquatic life.

8.Taste and Odor. None in such concentrations or combinations that are aesthetically objectionable, that would impair any use assigned to this class, or that would cause tainting or undesirable flavors in the edible portions of aquatic life.

(b)Class B. Those Inland Waters so designated pursuant to 314 CMR 4.06; including, without limitation, certain wetlands designated in 314 CMR 4.06(2); certain other waters designated in 314 CMR 4.06(5); and certain qualified waters designated in 314 CMR 4.06(6)(b). These waters are designated as a habitat for fish, other aquatic life, and wildlife, including for their reproduction, migration, growth and other critical functions, and for primary and secondary contact recreation. Where designated in 314 CMR 4.06(1)(d)6. and (6)(b) as a "Treated Water Supply", they shall be suitable as a source of public water supply with appropriate treatment. Class B waters shall be suitable for irrigation and other agricultural uses and for compatible industrial cooling and process uses. These waters shall have consistently good aesthetic value.

2.Temperature.

a. Shall not exceed 68°F (20°C) based on the mean of the daily maximum temperature over a seven-day period in cold water fisheries, unless naturally occurring. Where a reproducing cold water aquatic community exists at a naturally occurring higher temperature, the temperature necessary to protect the community shall not be exceeded and the natural daily and seasonal temperature fluctuations necessary to protect the community shall be maintained. Temperature shall not exceed 83°F (28.3°C) in warm water fisheries. The rise in temperature due to a discharge shall not exceed 3°F (1.7°C) in rivers and streams designated as cold water fisheries nor 5°F (2.8°C) in rivers and streams designated as warm water fisheries (based on the minimum expected flow for the month); in lakes and ponds the rise shall not exceed 3°F (1.7EC) in the epilimnion (based on the monthly average of maximum daily temperature);

d. in the case of a cooling water intake structure regulated by EPA under 33 U.S.C. § 1251 (FWPCA § 316(b)), the Department has the authority under 33 U.S.C. § 1251 (FWPCA § 401), M.G.L. c. 21, §§ 26 through 53 and 314 CMR 3.00: Surface Water Discharge Permit Program to condition the cooling water intake structure to assure compliance of the withdrawal activity with 314 CMR 4.00 including, but not limited to, compliance with narrative and numerical criteria and protection of existing and designated uses.

3.pH. Shall be in the range of 6.5 through 8.3 standard units and not more than 0.5 units outside of the natural background range. There shall be no change from natural background conditions that would impair any use assigned to this Class.

4.Bacteria. For protection of primary contact recreation, surface waters shall meet the minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)1. and 3.

5.Solids. These waters shall be free from floating, suspended and settleable solids in concentrations and combinations that would impair any use assigned to this Class, that would cause aesthetically objectionable conditions, or that would impair the benthic biota or degrade the chemical composition of the bottom.

6.Color and Turbidity. These waters shall be free from color and turbidity in concentrations or combinations that are aesthetically objectionable or would impair any use assigned to this Class.

8.Taste and Odor. None in such concentrations or combinations that are aesthetically objectionable, that would impair any use assigned to this Class, or that would cause tainting or undesirable flavors in the edible portions of aquatic life.

(c)Class SC. These Coastal and Marine Waters are designated as a habitat for fish, other aquatic life and wildlife including, for their reproduction, migration, growth and other critical functions, and for secondary contact recreation. They shall also be suitable for certain industrial cooling and process uses. These waters shall have good aesthetic value.

1.Dissolved Oxygen. Shall not be less than 5.0 mg/L at least 16 hours of any 24-hour period and not less than 4.0 mg/L at any time. Where natural background conditions are lower, DO shall not be less than natural background. Natural seasonal and daily variations that are necessary to protect existing and designated uses shall be maintained.

2.Temperature.

a. Shall not exceed 85°F (29.4°C) nor shall the rise due to a discharge exceed 5°F (2.8°C);

b. there shall be no change from natural background conditions that would impair any use assigned to this class, including those conditions necessary to protect normal species diversity, successful migration, reproductive functions or growth of aquatic organisms;

c. alternative effluent limitations established in connection with a variance for a thermal discharge issued under 33 U.S.C. § 1251 (FWPCA, § 316(a)) and 314 CMR 3.00 are in compliance with 314 CMR 4.00. As required by 33 U.S.C. § 1251 (FWPCA, § 316(a)) and 314 CMR 3.00: Surface Water Discharge Permit Program, for permit and variance renewal, the applicant must demonstrate that alternative effluent limitations continue to comply with the variance standard for thermal discharges; and

3.pH. Shall be in the range of 6.5 through 9.0 standard units and not more than 0.5 standard units outside of the natural background range. There shall be no change from natural background conditions that would impair any use assigned to this Class.

4.Bacteria. In lieu of meeting the minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)2. and 3., concentrations of enterococci bacteria in Class SC Surface Waters shall satisfy 314 CMR 4.05(4)(c)4.a. and b., whenever necessary for the protection of secondary contact recreation. It shall hereby be presumed that such protection is necessary year-round, provided, however, in the context of the issuance of a particular permit or approval by the Department, this presumption may be rebutted for a particular surface water or segment during periods of reduced frequency of use due to cold weather or otherwise (e.g., during the winter months, generally November through March). All such permits or approvals will be publicly available for review in accordance with the applicable regulations for that permit or approval.

a. Concentrations shall not exceed 175 colony forming units (cfu) per 100 mL, calculated as a geometric mean of all samples collected within any 90-day or smaller interval.

b. No more than 10% of all such samples described in 314 CMR 4.05(4)(c)4.a. shall exceed 350 cfu per 100 mL.

5.Solids. These waters shall be free from floating, suspended and settleable solids in concentrations and combinations that would impair any use assigned to this class, that would cause aesthetically objectionable conditions, or that would impair the benthic biota or degrade the chemical composition of the bottom.

6.Color and Turbidity. These waters shall be free from color and turbidity in concentrations or combinations that are aesthetically objectionable or would impair any use assigned to this class.

7.Oil and Grease. These waters shall be free from oil, grease and petrochemicals that produce a visible film on the surface of the water, impart an oily taste to the edible portions of aquatic life, coat the banks or bottom of the water course, or are deleterious or become toxic to aquatic life.

(4)Coastal and Marine Classes.

(a)Class SA. Those Coastal and Marine Waters so designated pursuant to 314 CMR 4.06; including, without limitation, 314 CMR 4.06(2) and (5), and certain qualified waters designated in 314 CMR 4.06(6)(b). These waters are designated as an excellent habitat for fish, other aquatic life and wildlife, including for their reproduction, migration, growth and other critical functions, and for primary and secondary contact recreation. In certain waters, excellent habitat for fish, other aquatic life and wildlife may include, but is not limited to, seagrass. Where designated for shell fishing in 314 CMR 4.06(6)(b), these waters shall be suitable for shellfish harvesting without depuration (Approved and Conditionally Approved Shellfish Areas). These waters shall have excellent aesthetic value. In the case of a water intake structure at a desalination facility, the Department has the authority under 33 U.S.C. § 1251 (FWPCA § 401), M.G.L. c. 21, §§ 26 through 53 and 314 CMR 3.00: Surface Water Discharge Permit Program to condition the water intake structure to assure compliance of the withdrawal activity with 314 CMR 4.00 including, but not limited to, compliance with the narrative and numerical criteria and protection of existing and designated uses.

1.Dissolved Oxygen. Shall not be less than 6.0 mg/L. Where natural background conditions are lower, DO shall not be less than natural background. Natural seasonal and daily variations that are necessary to protect existing and designated uses shall be maintained.

2.Temperature.

a. Shall not exceed 85°F (29.4°C) nor a maximum daily mean of 80°F (26.7°C), and the rise in temperature due to a discharge shall not exceed 1.5°F (0.8°C);

b. there shall be no change from natural background that would impair any uses assigned to this class, including those conditions necessary to protect normal species diversity, successful migration, reproductive functions or growth of aquatic organisms;

c. alternative effluent limitations established in connection with a variance for a thermal discharge issued under 33 U.S.C. § 1251 (FWPCA, § 316(a)) and 314 CMR 3.00: Surface Water Discharge Permit Program are in compliance with 314 CMR 4.00. As required by 33 U.S.C. § 1251 (FWPCA, § 316(a)) and 314 CMR 3.00, for permit and variance renewal, the applicant must demonstrate that alternative effluent limitations continue to comply with the variance standard for thermal discharges; and d. in the case of a cooling water intake structure regulated by EPA under 33 U.S.C. § 1251 (FWPCA § 316(b)), the Department has the authority under 33 U.S.C. § 1251 (FWPCA § 401), M.G.L. c. 21, §§ 26 through 53 and 314 CMR 3.00: Surface Water Discharge Permit Program to condition the cooling water intake structure to assure compliance of the withdrawal activity with 314 CMR 4.00 including, but not limited to, compliance with narrative and numerical criteria and protection of existing and designated uses.

3.pH. Shall be in the range of 6.5 through 8.5 standard units and not more than 0.2 standard units outside of the natural background range. There shall be no change from natural background conditions that would impair any use assigned to this Class.

4.Bacteria.

a. Waters designated for shell fishing: fecal coliform shall not exceed a geometric mean Most Probable Number (MPN) of 14 organisms per 100 mL, nor shall more than 10% of the samples exceed an MPN of 28 per 100 mL, or other values of equivalent protection based on sampling and analytical methods used by the Massachusetts Division of Marine Fisheries and approved by the National Shellfish Sanitation Program in the latest revision of the Guide for the Control of Molluscan Shellfish (more stringent regulations may apply, see314 CMR 4.06(1)(d)5.); and

b. For protection of primary contact recreation, surface waters shall meet the minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)2. and 3.

6.Color and Turbidity. These waters shall be free from color and turbidity in concentrations or combinations that are aesthetically objectionable or would impair any use assigned to this class.

7.Oil and Grease. These waters shall be free from oil and grease and petrochemicals.

8.Taste and Odor. None other than of natural origin.

(b)Class SB. Those Coastal and Marine Waters so designated pursuant to 314 CMR 4.06; including, without limitation, 314 CMR 4.06(2) and certain surface waters designated in 314 CMR 4.06(6)(b). These waters are designated as a habitat for fish, other aquatic life and wildlife, including for their reproduction, migration, growth and other critical functions, and for primary and secondary contact recreation. In certain waters, habitat for fish, other aquatic life and wildlife may include, but is not limited to, seagrass. Where designated for shell fishing in 314 CMR 4.06(6)(b), these waters shall be suitable for shellfish harvesting with depuration (Restricted and Conditionally Restricted Shellfish Areas). These waters shall have consistently good aesthetic value. In the case of a water intake structure at a desalination facility, the Department has the authority under 33 U.S.C. § 1251 (FWPCA § 401), M.G.L. c. 21, §§ 26 through 53 and 314 CMR 3.00: Surface Water Discharge Permit Program to condition the water intake structure to assure compliance of the withdrawal activity with 314 CMR 4.00 including, but not limited to, compliance with the narrative and numerical criteria and protection of existing and designated uses.

1.Dissolved Oxygen. Shall not be less than 5.0 mg/L. Where natural background conditions are lower, DO shall not be less than natural background. Natural seasonal and daily variations that are necessary to protect existing and designated uses shall be maintained.

2.Temperature.

a. Shall not exceed 85°F (29.4°C) nor a maximum daily mean of 80°F (26.7°C), and the rise in temperature due to a discharge shall not exceed 1.5°F (0.8°C) during the summer months (July through September) nor 4°F (2.2°C) during the winter months (October through June);

b. there shall be no changes from natural background that would impair any uses assigned to this class, including those conditions necessary to protect normal species diversity, successful migration, reproductive functions or growth of aquatic organisms;

4.Bacteria.

b. For protection of primary contact recreation, surface waters shall meet the minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)2. and 3.

6.Color and Turbidity. These waters shall be free from color and turbidity in concentrations or combinations that are aesthetically objectionable or would impair any use assigned to this class.

2.Temperature.

a. Shall not exceed 85°F (29.4°C) nor shall the rise due to a discharge exceed 5°F (2.8°C);

a. Concentrations shall not exceed 175 colony forming units (cfu) per 100 mL, calculated as a geometric mean of all samples collected within any 90-day or smaller interval.

b. No more than 10% of all such samples described in 314 CMR 4.05(4)(c)4.a. shall exceed 350 cfu per 100 mL.

6.Color and Turbidity. These waters shall be free from color and turbidity in concentrations or combinations that are aesthetically objectionable or would impair any use assigned to this class.

(5)Additional Minimum Criteria Applicable to All Surface Waters.

(a)Aesthetics. All surface waters shall be free from pollutants in concentrations or combinations that settle to form objectionable deposits; float as debris, scum or other matter to form nuisances; produce objectionable odor, color, taste or turbidity; or produce undesirable or nuisance species of aquatic life.

(b)Bottom Pollutants or Alterations. All surface waters shall be free from pollutants in concentrations or combinations or from alterations that adversely affect the physical or chemical nature of the bottom, interfere with the propagation of fish or shellfish, or adversely affect populations of non-mobile or sessile benthic organisms.

(c)Nutrients. Unless naturally occurring, all surface waters shall be free from nutrients in concentrations that would cause or contribute to impairment of existing or designated uses and shall not exceed the site-specific criteria developed in a TMDL or as otherwise established by the Department pursuant to 314 CMR 4.00 including, but not limited to, those established in 314 CMR 4.06(6)(c): Table 28: Site-specific Criteria. Any existing point source discharge containing nutrients in concentrations that would cause or contribute to cultural eutrophication, including the excessive growth of aquatic plants or algae, in any surface water shall be provided with the most appropriate treatment as determined by the Department, including, where necessary, highest and best practical treatment (HBPT) for POTWs and BAT for non-POTWs, to remove such nutrients to ensure protection of existing and designated uses. Human activities that result in the nonpoint source discharge of nutrients to any surface water may be required to be provided with cost effective and reasonable best management practices for nonpoint source control.

(d)Radioactivity. All surface waters shall be free from radioactive substances in concentrations or combinations that would be harmful to human, animal or aquatic life or the most sensitive designated use; result in radionuclides in aquatic life exceeding the recommended limits for consumption by humans; or exceed Massachusetts Drinking Water Regulations as set forth in 310 CMR 22.09A: Maximum Radionuclide Contaminant Levels, Monitoring Requirements and Analytical Methods Effective as of December 8, 2003.

(e)Toxic Pollutants. All surface waters shall be free from pollutants in concentrations or combinations that are toxic to humans, aquatic life or wildlife.

1.Generally Applicable Criteria. For each pollutant identified in 314 CMR 4.06(6)(d): Table 29: Generally Applicable Criteria, the concentrations identified or calculated for that pollutant in or pursuant to Table 29 shall be generally applicable criteria for all categories of surface waters, as specified therein; unless the Department determines that naturally occurring background concentrations are higher. Where the Department determines that naturally occurring background concentrations are higher, those concentrations shall be the allowable receiving water concentrations. (For purposes of convenience, Table 29 also references certain pollutants for which 314 CMR 4.05(3), (4) or (5)(a), (5)(b), (5)(c), (5)(d) or (5)(f) establish criteria.)

2.Use of Toxic Pollutant Criteria. For any discharge of a pollutant described in 314 CMR 4.05(5)(e) requiring a permit or approval:

a.Accumulation of Pollutants. Where appropriate, the Department shall use an additional margin of safety when establishing water quality based effluent limits to assure that pollutants do not persist in the environment or accumulate in organisms to levels that:

i. are toxic to humans, wildlife or aquatic life; or

ii. result in unacceptable concentrations in edible portions of marketable fish or shellfish or for the recreational use of fish, shellfish, other aquatic life or wildlife for human consumption.

b.Public Notice. Where toxic pollutant criteria as established under 314 CMR 4.00 are used to determine water quality based effluent limitations in a permit or approval, these effluent limitations and the criteria used shall be documented and subject to all applicable public notice requirements for the permit or approval.

c.Expression of Metal Concentrations. Metal concentrations in effluent limitations shall be expressed as total recoverable metals. Translation from dissolved metals criteria to total recoverable metals concentrations shall be based on the conversion factors set forth in Appendix F of Table 29a at 314 CMR 4.06(6)(d): Table 29: Generally Applicable Criteria.

d.Methods for Data Collection and Calculation of Instantaneous and Final Equation- and Model-based Criteria Values. Use of pollutant criteria established in 314 CMR 4.05(5)(e)1. which are equation- or model-based to develop water quality based effluent limits shall be subject to the following:

i. where ambient water quality data are required as inputs to equation- or modelbased criteria to calculate instantaneous criteria values, sampling and analysis shall be conducted in compliance with a quality assurance project plan (QAPP) approved by MassDEP which shall include collection of sufficient and representative data to reflect the impact of spatial, temporal, and hydrological variability on water chemistry in the receiving water at locations outside the influence of effluent discharge including, but not limited to, upstream samples or measurements, which shall be developed using applicable approved procedures as set forth in 314 CMR 4.03(6); and

ii. all final criteria values shall be calculated by MassDEP from multiple instantaneous criteria values using procedures that MassDEP has determined provide protection over the full range of seasonal and flow conditions throughout the year, including when the pollutant is most bioavailable and therefore is likely to have increased toxic effect.

e.Unlisted Pollutants; Combinations of Pollutants. Any pollutant or combination of pollutants within the meaning of 314 CMR 4.05(5)(e) for which 314 CMR 4.05(5)(e)1. does not establish a generally applicable criterion shall not be discharged to surface waters in a quantity or manner that would:

i. exceed safe exposure levels for aquatic life as determined by toxicity testing using methods approved by MassDEP pursuant to 314 CMR 4.03(6); or

ii. cause adverse human health effects due to the ingestion, inhalation or dermal absorption of such toxins attributable to such waters during their reasonable use as designated in 314 CMR 4.00; or

iii. result in a human health excess lifetime cancer risk level greater than 10^-6 for individual carcinogens.

(f)Bacteria.

1.Inland Waters. Concentrations of bacteria in Inland Waters, subject to the reduced interval requirements set forth in 314 CMR 4.05(5)(f)3. as applicable, and except as otherwise provided in the seasonal exception set forth in 314 CMR 4.05(5)(f)4. as applicable, shall, on a year-round basis, satisfy either 314 CMR 4.05(5)(f)1.a. or b:

a. for E. coli:

i. concentrations shall not exceed 126 colony-forming units (cfu) per 100 mL, calculated as the geometric mean of all samples collected within any 90-day or smaller interval; and

ii. no more than 10% of all such samples shall exceed 410 cfu per 100 mL (a statistical threshold value); or

b. for enterococci:

i. concentrations shall not exceed 35 cfu per 100 mL, calculated as the geometric mean of all samples collected within any 90-day or smaller interval; and

ii. no more than 10% of all such samples shall exceed 130 cfu per 100 mL (the statistical threshold value).

c. The preceding requirements are summarized in the following table:

Bacterial Indicator	Bacterial Criteria for Inland Waters (cfu/100mL)*
Bacterial Indicator	Geometric Mean*	Statistical Threshold Value*
E. coli	<=126	<=410
enterococci	<=35	<=130
*The geometric mean for at least one indicator shall not be exceeded in any 90-day or smaller interval. No more than 10% of all samples collected within that interval shall exceed the statistical threshold value for that indicator.

2.Coastal and Marine Waters. Concentrations of bacteria in Coastal and Marine Waters, subject to the reduced interval requirements set forth in 314 CMR 4.05(5)(f)3. as applicable, and except as otherwise provided in the seasonal exception set forth in 314 CMR 4.05(5)(f)4. as applicable, shall, on a year-round basis, satisfy 314 CMR 4.05(5)(f)2.a.:

a. for enterococci:

i. concentrations shall not exceed 35 cfu per 100 mL, calculated as the geometric mean of all samples collected within any 90-day or smaller interval; and

ii. no more than 10% of all such samples shall exceed 130 cfu per 100 mL (the statistical threshold value).

b. The preceding requirements are summarized in the following table:

Bacterial Indicator	Bacterial Criteria for Coastal and Marine Waters (cfu/100mL)*
	Geometric Mean*	Statistical Threshold Value*
enterococci	<=35	<=130
*The geometric mean for this indicator shall not be exceeded in any 90-day or smaller interval. No more than 10% of all samples collected within that interval shall exceed the statistical threshold value for this indicator.

3.Reduced Interval Requirements. The geometric mean and statistical threshold value used for calculating the minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)1. and 2., shall be calculated and assessed, respectively, over a 30-day or smaller interval in lieu of any otherwise applicable longer interval, if either of the conditions set forth in 314 CMR 4.05(5)(f)3.a.i. or ii. is met.

a. Conditions which require a reduced interval:

i. criteria are being applied to waters adjacent to any public or semi-public beach, at a location used for bathing and swimming purposes, and for the dates of operation of any such beach as posted or as otherwise established by the operator pursuant to 105 CMR 445.020: Operation; or

ii. criteria are being applied to segments impacted by CSO-, B(CSO)-, SB(CSO)-, or POTW-discharges.

b. Massachusetts Department of Public Health definitions: the terms "public bathing beach", "semi-public bathing beach" and "operator" as used in paragraph 314 CMR 4.05(5)(f)3.a.i. shall have the meanings as defined in 105 CMR 445.010: Public Bathing Beach; Semi-Public Bathing Beach; and Operator. (Standards and procedures for bathing water closures have been established by the Massachusetts Department of Public Health, at 105 CMR 445.000: Minimum Standards for Bathing Beaches (State Sanitary Code, Chapter VII).)

4.Seasonal Exception. The year-round minimum criteria for bacteria set forth in 314 CMR 4.05(5)(f)1. and 2., as subject to the reduced interval requirements set forth in 314 CMR 4.05(5)(f)3., as applicable, may be applied on a seasonal basis in lieu of a year-round basis upon MassDEP's determination that, because of a reduction in primary contact recreation during a specified period of time, such criteria are not needed to be protective. Bases for such determinations may include identification of periods when frequency of use is reduced due to cold weather (typically, from November through March); and/or consideration of other relevant and appropriate factors. Any such determinations shall be documented in writing (e.g., by the relevant provisions of surface water discharge permits issued pursuant to 314 CMR 3.00: Surface Water Discharge Permit Program) and made publicly available for review (e.g., through MassDEP's Surface Water Discharge Permit webpage).

5.Additional Bacteria Requirements. For additional bacteria requirements other than for primary contact recreation, see 314 CMR 4.05(3) and (4).

(g)Organoleptic Effect Pollutant Criteria. All surface waters shall be free from pollutants in concentrations that would exceed the organoleptic effect (e.g., taste and odor) criteria established in 314 CMR 4.06(6)(e): Table 30: Organoleptic Effect Criteria. Provided, however, that the more stringent of the following organoleptic effect criteria, as applicable, shall control:

1. the numeric criteria set forth in said Table 30; and

2. the following narrative criteria:

a. the taste and odor criteria set forth in 314 CMR 4.05(3) and (4); and

b. the aesthetic criteria set forth in 314 CMR 4.05(5)(a).

(6)Determining Aquatic Life Criteria Applicability Where Fresh Water and Coastal and Marine Waters Mix. 314 CMR 4.05(6) establishes whether fresh water or coastal and marine water aquatic life criteria, which are set forth in 314 CMR 4.05(3), (4) and (5), and in Table 29a at 314 CMR 4.06(6)(d): Table 29: Generally Applicable Criteria, shall apply. 314 CMR 4.05(6) shall apply, regardless of the designated class of water pursuant to 314 CMR 4.06.

(a) For surface waters and segments in which the salinity is equal to or less than 1 part per thousand (ppt) 95% or more of the time, fresh water criteria shall apply.

(b) For surface waters and segments in which the salinity is equal to or greater than 10 ppt 95% or more of the time, coastal and marine criteria shall apply.

(c) For surface waters and segments in which the salinity is between 1 and 10 ppt 95% or more of the time, the more stringent of the fresh water or the coastal and marine criteria shall apply, except as provided in 314 CMR 4.05(6)(d).

(d) For surface waters and segments in which the salinity is between 1 and 10 ppt 95% or more of the time, as an alternative to 314 CMR 4.05(6)(c), either the fresh water or the coastal and marine criteria may be applied, respectively, where a scientific analysis demonstrates that the biology of the surface water is dominated either by fresh water aquatic life or by coastal and marine aquatic life.

(7)Site-specific Criteria. Where the Department has established site-specific numerical minimum criteria for a pollutant, as described in 314 CMR 4.05(2), such criteria shall supersede any otherwise applicable minimum numerical criteria established in 314 CMR 4.00. For each pollutant identified in 314 CMR 4.06(6)(c): Table 28: Site-specific Criteria, the concentrations listed for that pollutant for each specified surface water or segment shall constitute site-specific criteria. Such site-specific criteria shall control over the generally applicable criteria listed in 314 CMR 4.06(6)(d). If, however, the Department determines that a more stringent requirement for a particular pollutant is necessary for the same surface water or segment pursuant to the narrative criteria set forth in 314 CMR 4.05(3), (4) or (5), the more stringent requirement shall be the criteria for that surface water or segment.

314 CMR, § 4.05

Amended by Mass Register Issue 1456, eff. 11/12/2021.

Amended by Mass Register Issue 1458, eff. 11/12/2021.

Amended by Mass Register Issue 1460, eff. 11/12/2021.