Storm Water Management

Storm Water Management

Traditionally, storm water management focused primarily on flood and erosion control. With increasing concern over water quality, groundwater recharge, stream bank protection, aquatic species and habitats, and other environmental concerns, storm water management now focuses on both storm water runoff quality and quantity.

What is Storm Water Runoff

Storm water runoff is rainfall or snow melt that does not soak into the ground (infiltrate due to impervious surfaces such as roof tops, roads, parking lots, and compacted lawns). Storm water runoff is collected and conveyed through storm sewer systems directly into streams, rivers, and lakes without being treated.

Storm Water Management Objectives for New Developments

1. Prevent loss of life and minimize property damage and health hazards.
2. Minimize inconvenience from flooding and surface ponding.
3. Minimize adverse impact on local groundwater systems and base flows in receiving watercourses.
4. Minimize downstream flooding.
5. Minimize pollution discharge to watercourses.
6. Minimize soil losses and sediments to sewer systems and water bodies from construction activity.
7. Promote orderly development in a cost-effective manner.

State of Iowa NPDES Phase II Storm Water Permitting

The U.S. Environmental Protection Agency has published final regulations for National Pollutant Discharge Elimination System (NPDES) Phase II Storm Water Permitting (40CFR parts 122 and 123). Included in the Federal Register is a listing of municipalities which will be required to comply with the regulations. The Iowa Department of Natural Resources (IDNR) has issued Draft "Individual Permits" which cover the municipal separate storm sewer system (MS4) of these municipalities. The IDNR Permit application contains information that will direct the municipal compliance efforts for a period of five years following issuance, at which time the permit is renewed. The Draft "Individual Permit" addresses the proposed regulatory requirements through a storm water discharge control program that specifies Best Management Practices (BMP) that meets the requirements of six minimum control measures. These six minimum control measures are designed to reduce pollutants to the Maximum Extent Possible (MEP) to protect water quality. The six minimum control measures are as follows: 

• Public Education and Outreach 
• Public Involvement and Participation 
• Illicit Discharge Detection and Elimination 
• Post-Construction Storm Water Management in New Development and Redevelopment 
• Pollution Prevention and Good Housekeeping for Municipal Operations
• Construction Storm Water Management

Each minimum control measure has "mandatory components" that must be addressed in the IDNR Permit, as well as "suggested components" that are deemed desirable by the USEPA/IDNR and would be voluntary on the part of the municipality. These six minimum controls measures are final at the present time, but may be modified by the Federal Government or the IDNR permitting authority. The released IDNR Draft permits for regulated MS4 are attached below for your review.


Storm Water Management and Erosion Control Documents

Individual Home Site SWPPP Guide
Post Construction Application
Storm Water Runoff Problems
Storm Water Pollution Solution
Home Building Erosion Control
Erosion Control Practices (BMP)

Public Service Announcements on Storm Water Pollution Prevention

Urban Stormwater Management ...Out of Sight Out of Mind
Sump Pump Discharge
2018 Stormwater Public Education
Short Videos on How You Can Help Prevent Pollution

Links to Additional Resources

Iowa Department of Natural Resources
Iowa Department of Natural Resources Storm Water Page
Iowa Storm Water Manual
Iowa Storm Water Education Partnership
Environmental Protection Agency (EPA)