Numeric Criteria Development

The information presented below gives a summary of state progress towards the development of numeric criteria. The information comes from EPA’s “State Adoption of Numeric Nutrient Standards (1998-2008)” report, current water quality standards, program activity measures, and nutrient criteria development plans. Links to the Virginia’s Nutrient Criteria Plan and state water quality standards are also provided.

• Existing Numeric Criteria
• Links to the Plan and Criteria
• Milestone Information

Existing Numeric Criteria

S = Statewide    W = For selected waterbody    N ⁄ A=Not Applicable

Note: See Statewide Criteria and Site-specific Criteria tabs for more information.

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Links to Numeric Nutrient Criteria Plan and Existing Nutrient Criteria

Plans:

• Nutrient Criteria Development Plan for the State of Virginia 2010 - submission with updates to 2004, 2006, and 2008 versions
• Nutrient Criteria Development Plan for the State of Virginia 2008 - submission with updates to 2004 and 2006 versions
• Nutrient Criteria Development Plan for the State of Virginia 2006 - submission with updates to the 2004 version

• ORSANCO Nutrient Criteria Plan September 2011
• ORSANCO Nutrient Criteria Plan March 2011

WQS: Virginia Water Quality Standards
Virginia DEQ: Water Quality Standards Exit

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Milestone Information - Development of Statewide Numeric N/P Criteria

Milestone information updated July 2012.

TN: Total Nitrogen; TP: Total Phosphorus

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Statewide Criteria

The information on this tab shows EPA-approved nutrient criteria for Virginia’s waterbodies. The language presented below comes directly from state water quality standards and applies to all waterbodies within the state (unless a waterbody type or designated use is noted). Criteria applicable to specific waterbodies within the state can be found on the “Site-specific Criteria” tab. For more information, refer to the Virginia water quality standards.

The following information reflects Virginia’s water quality standards posted to the Water Quality Standards Repository as of November 2010 (EPA-approved December 2009).

9 VAC 25-260-20. General criteria.
A. State waters, including wetlands, shall be free from substances attributable to sewage, industrial waste, or other waste in concentrations, amounts, or combinations which contravene established standards or interfere directly or indirectly with designated uses of such water or which are inimical or harmful to human, animal, plant, or aquatic life.

Specific substances to be controlled include, but are not limited to: floating debris, oil, scum, and floating materials; toxic substances including those which bioaccumulate; substances that produce color, tastes, turbidity, odors, or settle to form sludge deposits; and substances which nourish undesirable or nuisance aquatic plant life.

9 VAC 25-260-140. Criteria for surface water.
B. The following table is a list of numerical water quality criteria for specific parameters.
When information has become available from the Environmental Protection Agency to calculate additional aquatic life or human health criteria not contained in the table, the board may employ these values in establishing effluent limitations or other limitations pursuant to 9 VAC 25-260-20 A necessary to protect designated uses until the board has completed the regulatory standards adoption process.

Table of Parameters⁶

¹ One hour average concentration not to be exceeded more than once every 3 years on the average, unless otherwise noted.

² Four-day average concentration not to be exceeded more than once every 3 years on the average, unless otherwise noted.

³ Criteria have been calculated to protect human health from toxic effects through drinking water and fish consumption, unless otherwise noted and apply in segments designated as PWS in 9 VAC 25-260-390-540.

⁴ Criteria have been calculated to protect human health from toxic effects through fish consumption, unless otherwise noted and apply in all other surface waters not designated as PWS in 9 VAC 25-260-390-540.

⁶ The flows listed below are default design flows for calculating steady state waste load allocations unless statistically valid methods are employed which demonstrate compliance with the duration and return frequency of the water quality criteria.

Human Health:
Non-carcinogens     30Q5

The following are defined for this section:
“30Q5” means the lowest flow averaged over a period of 30 consecutive days that can be statistically expected to occur once every five climatic years.
“Averaged” means an arithmetic mean.
“Climatic year” means a year beginning on April 1 and ending on March 31.

Site-specific Criteria

The information on this tab shows EPA-approved site-specific nutrient criteria for Virginia’s waterbodies. Criteria on this page apply only to the waterbodies listed below. Criteria applicable to all waterbodies within the state are found on the “Statewide Criteria” tab. For more information, refer to the Virginia water quality standards.

The following information reflects Virginia’s water quality standards posted to the Water Quality Standards Repository as of November 2010 (EPA-approved December 2009).

9 VAC 25-260-185 Criteria to protect designated uses from the impacts of nutrients and suspended sediment in the Chesapeake Bay and its tidal tributaries.

¹ In applying this open-water instantaneous criterion to the Chesapeake Bay and its tidal tributaries where the existing water quality for dissolved oxygen exceeds an instantaneous minimum of 3.2 mg/L, that higher water quality for dissolved oxygen shall be provided antidegradation protection in accordance with section 30 subsection A.2 of this chapter.

B. Submerged Aquatic Vegetation and Water Clarity
If the submerged aquatic vegetation (SAV) acres in this subsection are met in any individual Chesapeake Bay Program segment as described in subsection D of this section, then the shallow-water submerged aquatic vegetation use is met in that segment. If the SAV acres in this subsection are not met in any individual Chesapeake Bay Program segment, then the water clarity criteria shall apply to the water clarity acres in that segment. If these water clarity criteria are met to the bottom water-sediment interface for the number of water clarity acres in that segment, then the shallow-water submerged aquatic vegetation use is met; regardless of the number of acres of SAV in that segment.

¹ The assessment period for SAV and water clarity acres shall be the single best year in the most recent three consecutive years. When three consecutive years of data are not available, a minimum of three years within the most recent five years shall be used.

² Percent Light through Water = 100e^(-KdZ) where K_d is water column light attenuation coefficient and can be measured directly or converted from a measured secchi depth where K_d = 1.45/secchi depth. Z = depth at location of measurement of K_d.

C. Chlorophyll a

9 VAC 25-260-187. Criteria for man-made lakes and reservoirs to protect aquatic life and recreational
designated uses from the impacts of nutrients.

A. The criteria in Section B apply to the man-made lakes and reservoirs listed in that section. Additional man-made lakes and reservoirs may be added as new reservoirs are constructed or monitoring data become available from outside groups or future agency monitoring.

B. Whether or not algicide treatments are used, the chlorophyll a criteria apply to all waters on the list. The total phosphorus criteria apply only if a specific man-made lake or reservoir received algicide treatment during the monitoring and assessment period of April 1 through October 31.

The 90^th percentile of the chlorophyll a data collected at one meter or less within the lacustrine portion of the manmade lake or reservoir between April 1 and October 31 shall not exceed the chlorophyll a criterion for that water body in each of the two most recent monitoring years that chlorophyll a data are available. For a water body that received algicide treatment, the median of the total phosphorus data collected at one meter or less within the lacustrine portion of the man-made lake or reservoir between April 1 and October 31 shall not exceed the total phosphorus criterion in each of the two most recent monitoring years that total phosphorus data are available.

Monitoring data used for assessment shall be from sampling location(s) within the lacustrine portion where observations are evenly distributed over the seven months from April 1 through October 31 and are in locations that are representative, either individually or collectively, of the condition of the man-made lake or reservoir.

Part VII
Special Standards and Scenic Rivers Listings.
9 VAC 25-260-310. Special standards and requirements.

The special standards are shown in small letters to correspond to lettering in the basin tables. The special standards are as follows:

aa. The following site-specific dissolved oxygen criteria apply to the tidal Mattaponi and Pamunkey Rivers and their tidal tributaries because of seasonal lower dissolved oxygen concentration due to the natural oxygen depleting processes present in the extensive surrounding tidal wetlands. These criteria apply June 1 - September 30 to Chesapeake Bay segments MPNTF, MPNOH, PMKTF, PMKOH and are implemented in accordance with subsection D of 9 VAC 25-260-185. These criteria supercede the open-water criteria listed in subsection A of 9 VAC 25-260-185.

bb. The following site specific numerical Chlorophyll a criteria apply March 1 - May 31 and July 1 - September 30 [as seasonal means] to the tidal James River (excludes tributaries) segments JMSTF2, JMSTF1, JMSOH, JMSMH, JMSPH and are implemented in accordance with subsection D of 9 VAC 25-260-185.

cc. For Mountain Lake in Giles County, Chlorophyll a shall not exceed 6 ug/L at a depth of 6 meters and orthophosphate-
P shall not exceed 8 ug/L at a depth of one meter or less.

dd. For Lake Drummond, located within the boundaries of Chesapeake and Suffolk in the Great Dismal Swamp, chlorophyll a shall not exceed 35 ug/L and total phosphorus shall not exceed 40 ug/L at a depth of one meter or less.