As used in this article, unless the context requires a different meaning: “Annual mass load of total nitrogen” (expressed in pounds per year) means the daily total nitrogen concentration (expressed as mg/L to the nearest 0.01 mg/L) multiplied by the flow volume of effluent discharged during the 24-hour period (expressed as MGD to the nearest 0.01 MGD), multiplied by 8.34 and rounded to the nearest whole number to convert to pounds per day (lbs/day) units, then totaled for the calendar month to convert to pounds per month (lbs/mo) units, and then totaled for the calendar year to convert to pounds per year (lbs/yr) units. “Annual mass load of total phosphorus” (expressed in pounds per year) means the daily total phosphorus concentration (expressed as mg/L to the nearest 0.01mg/L) multiplied by the flow volume of effluent discharged during the 24-hour period (expressed as MGD to the nearest 0.01 MGD) multiplied by 8.34 and rounded to the nearest whole number to convert to pounds per day (lbs/day) units, then totaled for the calendar month to convert to pounds per month (lbs/mo) units, and then totaled for the calendar year to convert to pounds per year (lbs/yr) units. “Association” means the Virginia Nutrient Credit Exchange Association authorized by this article. “Attenuation” means the rate at which nutrients are reduced through natural processes during transport in water. “Best management practice,” “practice,” or “BMP” means a structural practice, nonstructural practice, or other management practice used to prevent or reduce nutrient loads associated with stormwater from reaching surface waters or the adverse effects thereof. “Biological nutrient removal technology” means (i) technology that will achieve an annual average total nitrogen effluent concentration of eight milligrams per liter and an annual average total phosphorus effluent concentration of one milligram per liter, or (ii) equivalent reductions in loads of total nitrogen and total phosphorus through the recycle or reuse of wastewater as determined by the Department. “Delivered total nitrogen load” means the discharged mass load of total nitrogen from a point source that is adjusted by the delivery factor for that point source. “Delivered total phosphorus load” means the discharged mass load of total phosphorus from a point source that is adjusted by the delivery factor for that point source. “Delivery factor” means an estimate of the number of pounds of total nitrogen or total phosphorus delivered to tidal waters for every pound discharged from a permitted facility, as determined by the specific geographic location of the permitted facility, to account for attenuation that occurs during riverine transport between the permitted facility and tidal waters. Delivery factors shall be calculated using the Chesapeake Bay Program watershed model. “Department” means the Department of Environmental Quality. “Enhanced Nutrient Removal Certainty Program” or “ENRC Program” means the Phase III Watershed Implementation Plan Enhanced Nutrient Removal Certainty Program established pursuant to subsection G of § 62.1-44.19:14. “Equivalent load” means 2,300 pounds per year of total nitrogen and 300 pounds per year of total phosphorus at a flow volume of 40,000 gallons per day; 5,700 pounds per year of total nitrogen and 760 pounds per year of total phosphorus at a flow volume of 100,000 gallons per day; and 28,500 pounds per year of total nitrogen and 3,800 pounds per year of total phosphorus at a flow volume of 500,000 gallons per day. “Facility” means a point source discharging or proposing to discharge total nitrogen or total phosphorus to the Chesapeake Bay or its tributaries. This term does not include confined animal feeding operations, discharges of stormwater, return flows from irrigated agriculture, or vessels. “General permit” means the general permit authorized by this article. “MS4″ means a municipal separate storm sewer system. “Nutrient credit” or “credit” means a nutrient reduction that is certified pursuant to this article and expressed in pounds of phosphorus or nitrogen either (i) delivered to tidal waters when the credit is generated within the Chesapeake Bay Watershed or (ii) as otherwise specified when generated in the Southern Rivers watersheds. “Nutrient credit” does not include point source nitrogen credits or point source phosphorus credits as defined in this section. “Nutrient credit-generating entity” means an entity that generates nonpoint source nutrient credits. “Permitted facility” means a facility authorized by the general permit to discharge total nitrogen or total phosphorus. For the sole purpose of generating point source nitrogen credits or point source phosphorus credits, “permitted facility” shall also mean the Blue Plains wastewater treatment facility operated by the District of Columbia Water and Sewer Authority. “Permittee” means a person authorized by the general permit to discharge total nitrogen or total phosphorus. “Point source nitrogen credit” means the difference between (i) the waste load allocation for a permitted facility specified as an annual mass load of total nitrogen, and (ii) the monitored annual mass load of total nitrogen discharged by that facility, where clause (ii) is less than clause (i), and where the difference is adjusted by the applicable delivery factor and expressed as pounds per year of delivered total nitrogen load. “Point source phosphorus credit” means the difference between (i) the waste load allocation for a permitted facility specified as an annual mass load of total phosphorus, and (ii) the monitored annual mass load of total phosphorus discharged by that facility, where clause (ii) is less than clause (i), and where the difference is adjusted by the applicable delivery factor and expressed as pounds per year of delivered total phosphorus load. “State-of-the-art nutrient removal technology” means (i) technology that will achieve an annual average total nitrogen effluent concentration of three milligrams per liter and an annual average total phosphorus effluent concentration of 0.3 milligrams per liter, or (ii) equivalent load reductions in total nitrogen and total phosphorus through recycle or reuse of wastewater as determined by the Department. “Tributaries” means those river basins listed in the Chesapeake Bay TMDL and includes the Potomac, Rappahannock, York, and James River Basins, and the Eastern Shore, which encompasses the creeks and rivers of the Eastern Shore of Virginia that are west of Route 13 and drain into the Chesapeake Bay. “Waste load allocation” means (i) the water quality-based annual mass load of total nitrogen or annual mass load of total phosphorus allocated to individual facilities pursuant to the Water Quality Management Planning Regulation (9VAC25-720) or its successor, or permitted capacity in the case of nonsignificant dischargers; (ii) the water quality-based annual mass load of total nitrogen or annual mass load of total phosphorus acquired pursuant to § 62.1-44.19:15 for new or expanded facilities; or (iii) applicable total nitrogen or total phosphorus waste load allocations under the Chesapeake Bay total maximum daily loads (TMDLs) to restore or protect the water quality and beneficial uses of the Chesapeake Bay or its tidal tributaries.