Virginia Administrative Code › Title 9 - ENVIRONMENT › Agency 25 - STATE WATER CONTROL BOARD › Chapter 260 - WATER QUALITY STANDARDS › Part I - Surface Water Standards with General, Statewide Application › Section 9VAC25-260-155 - Ammonia surface water quality criteria

Current through Register Vol. 40, No. 24, July 15, 2024
A. The Department of Environmental Quality,
				  after consultation with the Virginia Department of Wildlife Resources and the
				  U.S. Fish and Wildlife Service, has determined that the majority of Virginia
				  freshwaters are likely to contain, or have contained in the past, freshwater
				  mussel species in the family Unionidae and contain early life stages of fish
				  during most times of the year. Therefore, the ammonia criteria presented in
				  subsections B and C of this section are designed to provide protection to these
				  species and life stages. In an instance where it can be adequately demonstrated
				  that either freshwater mussels or early life stages of fish are not present in
				  a specific waterbody, potential options for alternate, site-specific criteria
				  are presented in subsection D of this section. Acute criteria are a one-hour
				  average concentration not to be exceeded more than once every three
				  years1 on the average, and chronic criteria are
				  30-day average concentrations not to be exceeded more than once every three
				  years on the average.2 In addition, the four-day
				  average concentration of total ammonia nitrogen (in mg N/L) shall not exceed
				  2.5 times the chronic criterion within a 30-day period more than once every
				  three years on the average.
1The default design flow for
					 calculating steady state wasteload allocations for the acute ammonia criterion
					 for freshwater is the 1Q10 (see
					 9VAC25-260-140
					 B footnote 6) unless statistically valid methods are employed that demonstrate
					 compliance with the duration and return frequency of the water quality
					 criteria.
2The default design flow for
					 calculating steady state wasteload allocations for the chronic ammonia
					 criterion for freshwater is the 30Q10 (see
					 9VAC25-260-140
					 B footnote 6) unless statistically valid methods are employed which demonstrate
					 compliance with the duration and return frequency of the water quality
					 criteria.
B. The acute
				  criteria for total ammonia (in mg N/L) for freshwaters with trout absent or
				  present are in the following tables:
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The acute criteria for trout present shall apply to all
					 Class V-Stockable Trout Waters and Class VI-Natural Trout Waters as listed in
					 9VAC25-260-390
					 through
					 9VAC25-260-540.
					 The acute criteria for trout absent apply to all other fresh waters.
To calculate total ammonia nitrogen acute criteria values
					 in freshwater at different pH values than those listed in this subsection, use
					 the following equations and round the result to two significant digits:
Where trout are absent:
Acute Criterion Concentration (mg N/L) =
0.7249 X (
0.0114
+
1.6181
) X MIN
1 +
								107.204-pH
1 +
								10pH-7.204
Where MIN = 51.93 or 23.12 X 100.036 X (20 -
						T), whichever is less
T = Temperature in °C
Or where trout are present, whichever of the following
					 calculation results is less:
Acute Criterion Concentration (mg N/L) =
(
0.275
+
39.0
)
1 +
								107.204-pH
1 +
								10pH-7.204
or
0.7249 X (
0.0114
+
1.6181
) X (23.12 X 100.036X(20 °
								  T))
1 +
								107.204-pH
1 +
								10pH-7.204
T = Temperature in °C
C. The chronic criteria for total ammonia
				  nitrogen (in mg N/L) where freshwater mussels and early life stages of fish are
				  present in freshwater are in the following table:
View Image
To calculate total ammonia nitrogen chronic criteria values
					 in freshwater when freshwater mussels and early life stages of fish are present
					 at different pH and temperature values than those listed in this subsection,
					 use the following equation and round the result to two significant
					 digits:
Chronic Criteria Concentration =
0.8876 X (
0.0278
+
1.1994
) X (2.126 X 100.028 X (20 -
								  MAX(T,7)))
1 + 107.688-pH
1 + 10pH-7.688
Where MAX = 7 or temperature in degrees Celsius, whichever
					 is greater
T = temperature in °C
D. Site-specific considerations and alternate
				  criteria. If it can be adequately demonstrated that freshwater mussels or early
				  life stages of fish are not present at a site, then alternate site-specific
				  criteria can be considered using the information provided in this subsection.
				  Recalculated site-specific criteria shall provide for the attainment and
				  maintenance of the water quality standards of downstream waters.
1. Site-specific modifications to the ambient
				  water quality criteria for ammonia to account for the absence of freshwater
				  mussels or early life stages of fish shall be conducted in accordance with the
				  procedures contained in this subdivision. Because the department presumes that
				  most state waterbodies have freshwater mussels and early life stages of fish
				  present during most times of the year, the criteria shall be calculated
				  assuming freshwater mussels and early life stages of fish are present using
				  subsections B and C of this section unless the following demonstration that
				  freshwater mussels or early life stages of fish are absent is successfully
				  completed. Determination of the absence of freshwater mussels requires special
				  field survey methods. This determination must be made after an adequate survey
				  of the waterbody is conducted by an individual certified by the Virginia
				  Department of Wildlife Resources for freshwater mussel identification and
				  surveys. Determination of absence of freshwater mussels will be done in
				  consultation with the Department of Wildlife Resources. Early life stages of
				  fish are defined in subdivision 2 of this subsection. Modifications to the
				  ambient water quality criteria for ammonia based on the presence or absence of
				  early life stages of fish shall only apply at temperatures below 15°C.
a. During the review of any new or existing
				  activity that has a potential to discharge ammonia in amounts that may cause or
				  contribute to a violation of the ammonia criteria contained in subsection B of
				  this section, the department may examine data from the following approved
				  sources in subdivisions 1 a (1) through (5) of this subsection or may require
				  the gathering of data in accordance with subdivisions 1 a (1) through (5) on
				  the presence or absence of early life stages of fish in the affected waterbody.
(1) Species and distribution data contained
				  in the Virginia Department of Wildlife Resources Wildlife Information System
				  database.
(2) Species and
				  distribution data contained in Freshwater Fishes of Virginia, 1994.
(3) Data and fish species distribution maps
				  contained in Handbook for Fishery Biology, Volume 3, 1997.
(4) Field data collected in accordance with
				  U.S. EPA's Rapid Bioassessment Protocols for Use in Streams and Wadeable
				  Rivers, Second Edition, EPA 841-B-99-002. Field data must comply with all
				  quality assurance and quality control criteria.
(5) The American Society for Testing and
				  Materials (ASTM) Standard E-1241-88, Standard Guide for Conducting Early
				  Life-Stage Toxicity Tests with Fishes.