Stormwater & Nutrient Management Standards

control standards

State Rules and Control Requirements for Development Projects

These apply to projects beyond single-family and duplex lots. Development thresholds are now defined within the Rules, and additional measures capture project expansion in non-residential and multi-family areas. State and federal projects not reviewed under the local program must obtain approval from the North Carolina Department of Environmental Quality (DEQ). 

All development projects must meet nutrient export limits using the Stormwater Nutrient Accounting Tool (SNAP) or an equivalent approved method:

  • Neuse River Basin: 3.6 lb N/ac/yr
  • Tar-Pamlico River Basin: 4.0 lb N/ac/yr, 0.8 lb P/ac/yr

Stormwater Treatment Requirements

  • Built-Upon Area (BUA): 
    Onsite treatment is required when project density exceeds 24% BUA and must meet low- or high-density design standards.
  • Water Supply Watersheds: 
    Additional treatment may apply under the DEMLR Water Supply Watershed Rule.
  • Regional SCMs: 
    Shared or regional Stormwater Control Measures may serve multiple unrelated projects.
  • Runoff Volume Match: 
    Projects meeting the “runoff volume match” standard are exempt from further nutrient export requirements.
  • Peak Flow: 
    While the state rule does not require a 1-year, 24-hour peak flow rate match, Pitt County continues to enforce this local standard.

Nutrient Offset Options

  • Offsets may be used when onsite treatment does not meet nutrient reduction targets.
  • Projects under 24% BUA may use offsets for all reductions but must still comply with low-density stormwater standards (15A NCAC 02H .1003).
  • Public road and sidewalk expansions may satisfy all reduction goals through offsets.
  • The SNAP Tool can automatically generate local government offset approval forms.
  • Offsets are purchased in pounds per year of nitrogen or phosphorus.
  • No retrofit identification is required under the new rules.

Program Oversight and Reporting

  • Ensure long-term maintenance of SCMs and continued compliance for the life of each development within the Neuse and Tar-Pamlico basins.
  • Submit annual reports to the Division of Water Quality (DWQ) documenting progress and including all data entered into the SNAP Tool.