Criteria for Class I Waters — Water Contact Recreation and Protection of Nontidal Warmwater Aquatic Life. Bacteriological. Table 1. Bacteria Indicator Criteria Magnitudes The geometric mean of samples taken over a 90 day period shall not exceed the steady state geometric mean values for the given indicator. 10 percent of samples taken over a 90 day period shall not exceed the statistical threshold value. When a sanitary survey and an epidemiological study approved by the Department disclose no significant health hazard, the criteria in Table 1 do not apply. Dissolved Oxygen. The dissolved oxygen concentration may not be less than 5 milligrams/liter at any time. Temperature. The maximum temperature outside the mixing zone determined in accordance with Regulation .05 of this chapter or COMAR 26.08.03.03—.05 may not exceed 90°F (32°C) or the ambient temperature of the surface waters, whichever is greater. A thermal barrier that adversely affects aquatic life may not be established. Ambient temperature is the water temperature that is not impacted by a point source discharge. Ambient temperature shall be measured in areas of the stream representative of typical or average conditions of the stream segment in question. The Department may determine specific temperature measurement methods, times, and locations. pH. Normal pH values may not be less than 6.5 or greater than 8.5. Turbidity. Turbidity may not exceed levels detrimental to aquatic life. Turbidity in the surface water resulting from any discharge may not exceed 150 units at any time or 50 units as a monthly average. Units shall be measured in Nephelometer Turbidity Units. Color. Color in the surface water may not exceed 75 units as a monthly average. Units shall be measured in Platinum Cobalt Units. Toxic Substance Criteria. All toxic substance criteria to protect: Fresh water aquatic organisms apply in waters designated as fresh water in Regulation .03-1B; Estuarine or salt water aquatic organisms apply in waters designated as estuarine or salt waters as specified in Regulation .03-1B; and The wholesomeness of fish for human consumption apply in fresh, estuarine, and salt waters. Criteria for Subcategory Class I-P Waters — Water Contact Recreation, Protection of Nontidal Warmwater Aquatic Life and Public Water Supply. The following criteria apply: The criteria for Class I waters in §A(1)—(6); and Toxic Substance Criteria. All toxic substance criteria: For protection of fresh water aquatic organisms apply; and To protect public water supplies and the wholesomeness of fish for human consumption apply. Criteria for Class II Waters — Support of Estuarine and Marine Aquatic Life and Shellfish Harvesting. Bacteriological Criteria. These criteria are the same as for Class I, criteria for protection of recreational use, except, in Shellfish Harvest Waters, the following criteria also apply. In Shellfish Harvest waters, there may not be any pathogenic or harmful organisms in sufficient quantities to constitute a public health hazard in the use of waters for shellfish harvesting. A public health hazard for the consumption of raw shellfish will be presumed: If the most probable number (MPN) of fecal coliform organisms exceeds a median concentration of 14 MPN per 100 milliliters; If more than 10 percent of samples taken exceed 43 MPN per 100 milliliters for a 5-tube decimal dilution test or 49 per 100 milliliters for a 3-tube decimal dilution test; or Except when a sanitary survey approved by the Department of the Environment discloses no significant health hazard, §C(1)(a) and (b) do not apply and a public health hazard from the consumption of shellfish will not be presumed. Classification of Class II Waters for Harvesting. Approved classification means that the median fecal coliform MPN of at least 30 water sample results taken over a 3-year period to incorporate inter-annual variability does not exceed 14 per 100 milliliters; and: In areas affected by point source discharges, not more than 10 percent of the samples exceed an MPN of 43 per 100 milliliters for a five tube decimal dilution test or 49 MPN per 100 milliliters for a three tube decimal dilution test; or In other areas, the 90th percentile of water sample results does not exceed an MPN of 43 per 100 milliliters for a five tube decimal dilution test or 49 MPN per 100 milliliters for a three tube decimal dilution test. Conditionally approved classification means that the Department has determined that under certain conditions an area is restricted, but when not restricted, meets the conditions for the approved classification. Restricted classification means that the median fecal coliform MPN of at least 30 water sample results taken over a 3-year period does not exceed 88 per 100 milliliters or that the Department has determined that a public health hazard exists; and: In areas affected by point source discharges, not more than 10 percent of the samples exceed an MPN of 260 per 100 milliliters for a five tube decimal dilution test or 300 MPN per 100 milliliters for a three tube decimal dilution test; or In other areas, the 90th percentile of water sample results does not exceed an MPN of 260 per 100 milliliters for a five tube decimal dilution test or 300 MPN per 100 milliliter for a three tube decimal dilution test. Prohibited classification means that the fecal coliform values exceed those required for the restricted classification or is an area designated by the Department as a closed safety zone adjacent to a sewage treatment facility outfall or is an area closed due to a known pollution source. Temperature — same as Class I waters. pH — same as Class I waters. Turbidity — same as Class I waters. Color — same as Class I waters. Toxic Substance Criteria. All toxic substance criteria to protect: Estuarine or salt water aquatic organisms apply in accordance with the requirements of Regulation .03-1B; and The wholesomeness of fish for human consumption apply. Dissolved Oxygen Criteria for Class II Waters. This criteria is the same as for Class I waters, except for the Chesapeake Bay mainstem and associated tidal tributary subcategories. Seasonal and Migratory Fish Spawning and Nursery Subcategory. The dissolved oxygen concentrations in areas designated as migratory spawning and nursery seasonal use shall be: Greater than or equal to 6 milligrams/liter for a 7-day averaging period from February 1 through May 31 (salinity less than or equal to 0.5 parts per thousand); Greater than or equal to 5 milligrams/liter as an instantaneous minimum from February 1 through May 31; and Applicable to the open-water fish and shellfish subcategory criteria from June 1 to January 31. The seasonal shallow-water submerged aquatic vegetation subcategory is the same as for the open-water fish and shellfish subcategory year-round. Open-Water Fish and Shellfish Subcategory. The dissolved oxygen concentrations in areas designated as open-water fish and shellfish subcategory shall be: Greater than or equal to 5.5 milligrams/liter for a 30-day averaging period year-round in tidal fresh waters (salinity less than or equal to 0.5 parts per thousand); Greater than or equal to 5 milligrams/liter for a 30-day averaging period year-round (salinity greater than 0.5 parts per thousand); Greater than or equal to 4.0 milligrams/liter for a 7-day averaging period year-round; Greater than or equal to 3.2 milligrams/liter as an instantaneous minimum year-round; For protection of the endangered shortnose sturgeon, greater than or equal to 4.3 milligrams/liter as an instantaneous minimum at water column temperatures greater than 29°C (77°F); and For the Upper Pocomoke River Tidal Fresh (POCTF) and the Maryland portion of the Middle Pocomoke River Oligohaline (POCOH), greater than or equal to 4.0 milligrams/liter for a 30-day averaging period year-round. Seasonal Deep-Water Fish and Shellfish Subcategory. The dissolved oxygen concentrations in areas designated as seasonal deep-water fish and shellfish subcategory shall be: Greater than or equal to 3.0 milligrams/liter for a 30-day averaging period from June 1 through September 30; Greater than or equal to 2.3 milligrams/liter for a 1-day averaging period from June 1 through September 30; Greater than or equal to 1.7 milligrams/liter as an instantaneous minimum from June 1 through September 30; The open-water fish and shellfish subcategory criteria apply from October 1 to May 31; and For the dissolved oxygen criteria restoration variance for Chesapeake Bay Mainstem Segment 4 mesohaline (CB4MH) seasonal deep-water fish and shellfish subcategory, not lower for dissolved oxygen in segment CB4MH than the stated criteria for the seasonal deep-water seasonal fish and shellfish use for more than 5 percent spatially and temporally (in combination), from June 1 to September 30. Seasonal Deep-Channel Refuge Subcategory. The dissolved oxygen concentrations in areas designated as deep-channel seasonal refuge use shall be: Greater than or equal to 1.0 milligrams/liter as an instantaneous minimum from June 1 through September 30 except for Chesapeake Bay segments subject to variances; For dissolved oxygen criteria restoration variance for Chesapeake Bay Mainstem Segment 4 mesohaline (CB4MH) deep-channel refuge subcategory, not lower for dissolved oxygen in segment CB4MH than the stated criteria for the seasonal deep-channel refuge for more than 6 percent spatially or temporally (in combination), from June 1 to September 30; For the dissolved oxygen criteria restoration variance for Eastern Bay Mesohaline (EASMH) seasonal deep-channel refuge subcategory, not lower for dissolved oxygen in segment EASMH than the stated criteria for the seasonal deep-channel refuge use for more than 2 percent spatially and temporally (in combination), from June 1 to September 30; and The same as for the open-water fish and shellfish subcategory from October 1 to May 31. Implementation of the Dissolved Oxygen Water Quality Standard. The attainment of the dissolved oxygen criteria that apply to the Chesapeake Bay and tidally influenced tributary waters shall be determined using the guidelines established in the U.S. Environmental Protection Agency publications “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries (EPA 903-R-03-002), Chapter III”; “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries — 2004 Addendum (EPA 903-R-04-005), Chapter V”; “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries — 2007 Addendum (EPA 903-R-07-003), Chapter IV”; “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries — 2008 Technical Support for Criteria Assessment Protocols Addendum (EPA 903-R-08-001), Chapter III”; “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries — 2010 Technical Support for Criteria Assessment Protocols Addendum (EPA 903-R-10-002), Chapters II and III”; and “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries — 2017 Technical Addendum (EPA 903-R-17-002), Chapters II and III”; which are incorporated by reference. Restoration Variance. The percentage of allowable exceedance for restoration variances is based on water quality modeling and incorporates the best available data and assumptions. The restoration variances are temporary, and will be reviewed at a minimum every three years, as required by the Clean Water Act and EPA regulations. The variances may be modified based on new data or assumptions incorporated into the water quality model. Water Clarity Criteria for Seasonal Shallow-Water Submerged Aquatic Vegetation Subcategory. Water Clarity Criteria Measurement. A Bay segment has attained the shallow water designated use if: Submerged aquatic vegetation (SAV) acreage meets or exceeds the SAV acreage restoration goal in Table 3 of this regulation; The shallow-water acreage that meets or exceeds the water clarity criterion expressed in Secchi depth equivalence from Table 2 of this regulation at the segment specific application depth specified in Regulation .08 of this chapter (excluding SAV no grow zones) is 2.5 times greater than the SAV Acreage Restoration Goal from Table 3 of this regulation; or A combination of the actual SAV acreage attained and meeting the applicable water clarity criteria in an additional, unvegetated shallow water surface area equals 2.5 times the remaining SAV acreage necessary to meet the segment's restoration goal. If none of §C(9)(a)(i), (ii), or (iii) applies, the segment has not attained the water clarity designated use. Table 2. Numerical Water Clarity Criteria (in Secchi Depth Equivalents) for General Application to Shallow Water Aquatic Vegetation Bay Grass Designated Use (Application Depths Given in 0.5 Meter Attainment Intervals1). Table 3. SAV Acreage Restoration Goals. SAV No Grow Zones. Certain Chesapeake Bay segments contain areas designated as shallow water use that are not suitable for growth of submerged aquatic vegetation due to natural conditions and permanent physical alterations. Tables V-1 and Figures V-1 to V-12 in the 2004 U.S. Environmental Protection Agency publication “Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability — 2004 Addendum (EPA 903-R-04-006)”, which is incorporated by reference, indicate the SAV No Grow Zones. The segments Upper Choptank River (CHOTF), Upper Nanticoke River (NANTF), Upper Pocomoke River (POCTF), and Middle Pocomoke River Oligohaline (POCOH) are entirely SAV no grow zones, therefore, the shallow-water designated use does not apply to these segments. Implementation. The attainment of the water clarity criteria that apply to the seasonal shallow-water submerged aquatic vegetation use subcategory in the Chesapeake Bay and tidally influenced tributary waters will be determined using the guidelines documented within the U.S. Environmental Protection Agency publications “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries (EPA 903-R-03-002)”, “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and its Tidal Tributaries — 2004 Addendum (EPA 903-R-04-005)”, “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and it Tidal Tributaries — 2007 Addendum (EPA 903-R-07-003)”, “Ambient Water Quality Criteria for Dissolved Oxygen, Water Clarity and Chlorophyll a for the Chesapeake Bay and Its Tidal Tributaries — 2008 Technical Support for Criteria Assessment Protocols Addendum (EPA 903-R-08-001)”, “Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability (EPA 903-R-03-004)”, and “Technical Support Document for Identification of Chesapeake Bay Designated Uses and Attainability — 2004 Addendum (EPA 903-R-04-006)” which are incorporated by reference. Chlorophyll a. Concentrations of chlorophyll a in free-floating microscopic aquatic plants (algae) may not exceed levels that result in ecologically undesirable consequences that would render tidal waters unsuitable for designated uses. Compliance Schedules for Protection of Downstream Uses in Tidal Waters. The compliance schedule provisions of COMAR 26.08.04.02C are applicable to discharge permits issued to existing dischargers which contain new or revised effluent limitations based on water quality standards contained in §C(8) and (9) of this regulation. An upstream state issuing discharge permits to existing dischargers which contain new or revised effluent limitations based on the water quality standards contained in §C(8) and (9) of this regulation may apply the compliance schedule provisions of COMAR 26.08.04.02C. Criteria for Class II-P Waters—Support of Estuarine and Marine Aquatic Life and Shellfish Harvesting and Public Water Supplies. The following criteria apply: The criteria for Class II waters in §C(1)—(8), (9)(a)—(c), (10), and (11); and All toxic substance criteria: For protection of fresh water and freshwater-adapted estuarine aquatic organisms apply; and To protect public water supplies and the wholesomeness of fish and shellfish for human consumption. Criteria for Class III Waters — Nontidal Cold Water. Bacteriological — Dissolved Oxygen. The dissolved oxygen concentration may not be less than 5 milligrams/liter at any time, with a minimum daily average of not less than 6 milligrams/liter. Temperature. The maximum temperature outside the mixing zone determined in accordance with Regulation .05 of this chapter or COMAR 26.08.03.03—.05 may not exceed 68°F (20°C) or the ambient temperature of the surface waters, whichever is greater. Ambient temperature — Same as Class I. A thermal barrier that adversely affects salmonid fish may not be established. It is the policy of the State that riparian forest buffer adjacent to Class III waters shall be retained whenever possible to maintain the temperatures essential to meeting this criterion. pH — same as Class I waters. Turbidity — same as Class I waters. Color — Same as Class I-P waters. Total Residual Chlorine (TRC). Except as provided in COMAR 26.08.03.06, the Department may not issue a permit allowing the use of chlorine or chlorine-containing compounds in the treatment of wastewaters discharging to Class III and Class III-P waters. Toxic Substance Criteria. All toxic substance criteria to protect: Fresh water aquatic organisms apply; and The wholesomeness of fish for human consumption apply. Criteria for Class III-P Waters — Nontidal Cold Water and Public Water Supplies. Exception. Authorized operation of the Little Seneca Creek Dam means that all operational activities permitted are met under the conditions of a dam operating permit issued by the Department of Natural Resources under Natural Resources Article, §§8-801—8-814, Annotated Code of Maryland, and COMAR 08.05.03. Injury resulting from the authorized operation of Little Seneca Creek Dam to the Class III natural trout fishery recognized in the stream use designation assigned to Little Seneca Creek in Regulation .08 of this chapter is not considered a violation of this chapter. The following criteria apply: The criteria for Class III waters in §D(1)—(7); and All toxic substance criteria to protect: Fresh water aquatic organisms; and Public water supplies and the wholesomeness of fish for human consumption. Criteria for Class IV Waters — Recreational Trout Waters. Bacteriological — same as Class I waters. Dissolved oxygen — same as Class I waters. Temperature. The maximum temperature outside the mixing zone determined in accordance with Regulation .05 of this chapter or COMAR 26.08.03.03—.05 may not exceed 75°F (23.9°C) or the ambient temperature of the surface waters, whichever is greater. Ambient temperature — Same as Class I. A thermal barrier that adversely affects salmonid fish may not be established. It is the policy of the State that riparian forest buffer adjacent to Class IV waters shall be retained whenever possible to maintain the temperatures essential to meeting this criterion. pH — same as Class I waters. Turbidity — same as Class I waters. Color — same as for Class I waters. Toxic Substance Criteria. All toxic substance criteria to protect: Fresh water aquatic organisms apply; and The wholesomeness of fish for human consumption apply. Criteria for Class IV-P Waters — Recreational Trout Waters and Public Water Supplies. The following criteria apply: The criteria for Class IV waters in §F(1)—(6); and Toxic Substance Criteria. All toxic substance criteria to protect: Fresh water aquatic organisms, and Public water supplies and the wholesomeness of fish for human consumption. Criteria for Public Water Supply Reservoirs. The following criteria apply in freshwater reservoirs designated Class I-P, III-P or IV-P: The arithmetic mean of a representative number of samples of chlorophyll a concentrations, measured during the growing season (May 1 to September 30) as a 30-day moving average may not exceed 10 micrograms per liter; and The 90th-percentile of measurements taken during the growing season may not exceed 30 micrograms per liter.