Information provided for reference purposes only

Note: This information is provided for reference purposes only. Although the information provided here was accurate and current when first created, it is now outdated. All the links in the document have been removed.


NPDES Storm Water MSGP: Visual Examinations

All facilities covered by the MSGP (except for Sector S - Air Transportation Facilities) are required to perform quarterly visual examinations of their storm water discharges for the purpose of visually inspecting storm water quality associated with storm water runoff or snow melt.  Visual examinations provide a simple and inexpensive means of obtaining a rough assessment of the effectiveness of a facility's SWPPP.  

Visual examinations should be: 

  • Performed at least once per quarter for the life of the permit (quarters are defined as: Jan-Mar, Apr-Jun, Jul-Sep and Oct-Dec)
  • Completed in a well lit area
  • Based on samples collected within the first 30 minutes of discharge (or as soon as practical, not to exceed 60 minutes)
  • Performed by the same person each quarter for the duration of the permit (where practical)
  • Examined for odor, color, clarity, floating solids, settled solids, suspended solids, foam, oil sheen and other obvious indicators of storm water pollution
  • Recorded in the Storm Water Pollution Prevention Plan


Coal mining-related facilities (Sector H) must perform visual monitoring within the first 60 minutes of discharge (or as soon thereafter as practical, but not to exceed 2 hours). Visual examinations are not required for inactive areas not under Surface Mining Control and Reclamation Act (SMCRA) bond. However, visual examinations must be performed:

  • Quarterly for active areas under SMCRA bond located in areas with annual precipitation greater than 20 inches; and
  • Semi-annually for inactive areas under SMCRA bond, and active areas under SMCRA bond located in areas with average annual precipitation of 20 inches or less. At least one examination must be performed during each of the following periods: January through June and July through December.


What Documentation Should be Prepared?

Visual examination reports must include:

  • Examination date and time
  • Examination personnel
  • Nature of discharge (i.e., runoff or snowmelt)
  • Visual quality of the storm water discharge
  • Probable sources


Do Visual Examination Results Need to be Reported?

No, unless specifically requested to do so by EPA. All results must be recorded and kept with the Storm Water Pollution Prevention Plan.

Do All Discharge Points Need to be Visually Examined?

No. Under certain conditions, a facility may determine one outfall to be a Representative Discharge. That is, the facility reasonably believes the discharge from two or more outfalls is substantially identical and therefore only inspects one outfall. Facilities must document their rationale for considering two outfalls to be identical and contain that explanation in the Storm Water Pollution Permit.  Also, for each representative outfall, an estimate the size of the drainage and an estimate of the runoff coefficient of the drainage area must also be provided in the SWPPP.  More information on Representative Discharges can be found in the Introductory Fact Sheet to the MSGP (Section VI.E.6).

What If a Visual Examination Can't be Performed?

The MSGP allows for waivers from visual examination requirements under two circumstances: adverse weather conditions, and unstaffed and inactive sites. It should be noted that these waivers cannot be used for compliance monitoring requirements associated with effluent limitations.

Adverse Weather Waiver

Adverse weather conditions that may prohibit the collection of samples include weather conditions that create dangerous conditions for personnel (such as local flooding, high winds, hurricanes, tornadoes, electrical storms, etc.) or otherwise make the collection of a sample impracticable (drought, extended frozen conditions, etc.).

The facility must document reasons for not performing the visual examination if adverse climate conditions preclude the discharger from performing the visual examination.  The facility must retain these records with the SWPPP.

Unstaffed and Inactive Sites

The facility must maintain a certification with the storm water pollution prevention plan stating that the site is inactive and unstaffed and that performing visual examinations during a qualifying event is not feasible.



Disclaimer: The information contained on these pages is a general statement of policy. It does not establish or affect legal rights or obligations. It does not establish a binding norm and is not finally determinative of the issues addressed. Agency decisions in any particular case will be made by applying the law and regulations to the specific facts of the case. This applies to all pages in the NPDES Storm Water Program web hierarchy (