United States

Environmental Protection

Agency

Office of Water

Washington, D.C.

EPA 832-F-99-024

September 1999

Storm Water

Management Fact Sheet

Storm Water Contamination Assessment

DESCRIPTION

A Storm Water Contamination Assessment (SWCA)

reviews a facility and/or a site to find materials or

practices that may contaminate storm water. This

assessment helps target the most important pollutant

sources for correction or prevention.

A SWCA program is closely related to other BMPs,

such as materials inventory, non-storm water

discharges, record keeping, and visual inspections.

APPLICABILITY

An SWCA program is applicable to any industrial

facility which contains areas, activities, or materials

which may contribute pollutants to storm water

runoff from the total site. An assessment for storm

water purposes may also be applicable in situations

where a formal site assessment for hazardous waste

purposes is being performed.

ADVANTAGES AND DISADVANTAGES

A comprehensive SWCA program can eliminate

pollution sources that can impair receiving water

quality. However, there are limitations associated

with a contamination assessment program,

including:

C Assessments need to be performed by

qualified personnel.

C Assessments are useful only if there is

corporate commitment to reduce any

contamination sources discovered.

C Assessments need to be periodically

updated.

KEY PROGRAM COMPONENTS

A SWCA program should include:

C Assessing potential pollutant sources and

associated high risk activities such as

loading and unloading operations, outdoor

storage activities, outdoor manufacturing or

processing activities, dust- or particulategenerating activities, and on-site waste

disposal practices.

C Determining which of these sources pose the

greatest risks of polluting storm water

runoff from the site.

C Selecting other cost-effective BMPs to

prevent or control pollution from the highrisk sources at the site.

IMPLEMENTATION

In addition to identifying problems within the storm

sewer system, it is even more important to prevent

problems from developing at all, and to provide an

environment in which future problems can be

avoided. Thus, an effective storm water assessment

program should include follow-up activities

including: 

C Educating the public about the

consequences of misusing storm sewers. 

C Pretreating industrial storm water or

disconnecting commercial and industrial

storm water entries into the storm drainage

system.

C Tackling the problem of widespread septic

system failure.
For more information contact:

Municipal Technology Branch

U.S. EPA

Mail Code 4204

401 M St., S.W.

Washington, D.C., 20460

C Disconnecting direct sanitary sewerage

connections from the storm sewer system.

C Rehabilitating storm or sanitary sewers to

abate infiltration by contaminated water.

C Developing zoning and other ordinances.

In some communities that are assumed to have

separate sanitary and storm sewer systems, the

storm sewer system may actually act as a combined

sewer system. In these cases, the community may

consider designating the storm sewer system a

combined sewer and treating the discharge. 

A SWCA program and the related correction

program need to be periodically updated, based on

their effectiveness and on the introduction of new

raw materials or changes in processes at the site.

Because the results and performance of a SWCA

program depend on the severity of the risks

uncovered and the corrective actions taken, it is

difficult to quantify the water quality benefits of a

risk assessment program. Clearly, however, a

program that identifies potential pollution sources

and corrects them will improve water quality. 

COSTS

Costs for the initial assessment may be high.

However, by pinpointing high risk areas, a risk

assessment may reduce overall costs associated with

a complete BMP implementation program. The

costs associated with a risk assessment program for

storm water are small when compared with those of

an overall hazardous waste site assessment.

REFERENCES

1. Pitt, R., D. Barbe, D. Adrian, and R. Field,

1992. Investigation of Inappropriate

Pollutant Entries into Storm Drainage

System - A User’s Guide, U.S. EPA,

Edison, New Jersey.

2. U.S. EPA, 1981. NPDES Best

Management Practices Guidance

Document.

3 U.S. EPA, Pre-print, 1992. Storm Water

Management for Industrial Activities:

Developing Pollution Prevention Plans and

Best Management Practices. EPA 832-R92-006.

ADDITIONAL INFORMATION

Center for Watershed Protection

Tom Schueler

8391 Main Street

Ellicott City, MD 21043

Northern Virginia Planning District Commission

David Bulova

7535 Little River Turnpike, Suite 100

Annandale, VA 22003

Oklahoma Department of Environmental Quality

Don Mooney

Water Quality Division, Storm Water Unit

P.O. Box 1677

Oklahoma City, OK 73101-1677

Southeastern Wisconsin Regional Planning

Commission

Bob Biebel

916 N. East Avenue, P.O. Box 1607

Waukesha, WI 53187

United States Postal Service

Charles Vidich

6 Griffin Road North

Windsor, CT 06006-7030

The mention of trade names or commercial products

does not constitute endorsement or recommendation

for the use by the U.S. Environmental Protection

Agency.