Section 40. Implementing Nitrogen and Phosphorus Waste Load Allocations in the Chesapeake Bay Watershed

A. Nitrogen and phosphorus waste load allocations assigned to individual significant dischargers in 9VAC25-720-50 C, 9VAC25-720-60 C, 9VAC25-720-70 C, 9VAC25-720-110 C, and 9VAC25-720-120 C may be exchanged in accordance with the Chesapeake Bay Watershed Nutrient Credit Exchange Program established under Article 4.02 (§ 62.1-44.19:12 et seq.) of Chapter 3.1 of Title 62.1 of the Code of Virginia. Exchanges must account for the delivery factor applicable to each discharge based upon its location within the river basin and calculated by the Chesapeake Bay Program watershed model.

B. The nitrogen and phosphorus waste load allocations assigned to individual significant dischargers in 9VAC25-720-50 C, 9VAC25-720-60 C, 9VAC25-720-70 C, 9VAC25-720-110 C, and 9VAC25-720-120 C are considered to be bioavailable to aquatic life. On a case-by-case basis, a discharger may demonstrate to the satisfaction of the board that a significant portion of the nutrients discharged by the facility is not bioavailable to aquatic life. In these cases, the board may limit the permitted discharge to reflect only that portion of the assigned waste load allocation that is bioavailable. Such limits shall be consistent with the assumptions and methods used to derive the allocations through the Chesapeake Bay watershed and water quality models.

C. Unless otherwise noted, the nitrogen and phosphorus waste load allocations assigned to individual significant dischargers in 9VAC25-720-50 C, 9VAC25-720-60 C, 9VAC25-720-70 C, 9VAC25-720-110 C, and 9VAC25-720-120 C are considered total loads including nutrients present in the intake water from the river, as applicable. On a case-by-case basis, an industrial discharger may demonstrate to the satisfaction of the board that a significant portion of the nutrient load originates in its intake water. In these cases, the board may limit the permitted discharge to reflect only the net nutrient load portion of the assigned waste load allocation. Such limits shall be consistent with the assumptions and methods used to derive the allocations through the Chesapeake Bay watershed and water quality models.

D. The board may amend this regulation to adjust individual nitrogen and phosphorus waste load allocations. Reasons for considering such an adjustment include, but are not limited to:

1. A discharger completes or does not complete a plant expansion as evidenced by issuance of a Certificate To Operate by December 31, 2010; or

2. A river basin nutrient load allocation is not achieved.

Any adjustment to an individual waste load allocation must ensure water quality standards are maintained.

Historical Notes

Derived from Volume 22, Issue 03, eff. November 16, 2005.

Statutory Authority

§ 62.1-44.15 of the Code of Virginia; § 303 of the federal Clean Water Act.