Stormwater | Municipal Separate Storm Sewer System (MS4)

Western Lake Erie Basin MapThe three rivers of Defiance are a vital asset; providing drinking water, wildlife habitat and recreational opportunities for residents and visitors alike. The Maumee River Watershed is the largest in the Great Lakes system, covering more than 8,300 square miles in Ohio, Indiana and Michigan. The Maumee River is formed in Fort Wayne by the Saint Joseph and Saint Marys Rivers, flowing in a northeasterly direction through Defiance where it is joined by the Tiffin and Auglaize Rivers before arriving in Toledo where it empties into Maumee Bay and Lake Erie. Read more about the Maumee Watershed.

Urbanization within our watershed brings an increase of pavement and rooftops, increasing the stormwater runoff which has a negative impact on the water quality of Lake Erie and also causes rivers to flood more quickly. Stormwater runoff collects dirt, debris, salt and other pollutants as it flows into storm drains that lead directly into our streams and rivers. Pollution and flooding are both reduced when runoff slows down, allowing rainwater to filter through grasses and soil.

Water Cycle Diagram

Stormwater Management

Storm Water Management Program 2021 to 2026The City of Defiance holds a stormwater permit with the Ohio Environmental Protection Agency for the Municipal Separate Storm Sewer System (MS4) under the National Pollutant Discharge Elimination System (NPDES). This permit requires the City to develop and follow a Stormwater Management Plan (SWMP) to preserve, protect and improve the water quality in the City of Defiance. Details are included in the full plan:

Storm Water Management Program (SWMP)

The City of Defiance Stormwater Division is responsible for implementing a Storm Water Management Program (SWMP) in accordance with Ohio Environmental Protection Agency (EPA) National Pollutant Discharge Elimination System (NPDES) Small MS4 General Permit. A Municipal Separate Storm Sewer System (MS4) is defined as a publicly-owned system used solely for conveying storm water; including storm drains, catch basins, curbs, gutters, ditches and man-made channels. The MS4 conveys water directly into surface water, such as rivers and streams.

EPA's MS4 Program

The purpose of the Ohio EPA's MS4 Program is to regulate sources to protect water quality and to establish a comprehensive storm water management program in each community. In this program, small MS4s like Defiance, have flexibility to determine the best management practices and measurable goals that are most appropriate for their system, based on each of the six minimum control measures described below. The Ohio EPA is the permitting authority for MS4's that are regulated by the U.S. EPA's Federal Water Pollution Control Act, commonly referred to as the Clean Water Act. The objective of the CWA is to restore and maintain the chemical, physical, and biological integrity of the nation's waters by preventing point and nonpoint pollution sources, providing assistance to publicly owned treatment works for the improvement of wastewater treatment, and maintaining the integrity of wetlands.

Storm Water: A Vital Natural Resource

Our quality of life and health is greatly dependent on the quality of our fresh water. Fish and other wildlife also rely on the responsible stewardship of our natural resources. Activities in our homes, yards and communities have an effect on the quality of our water supplies. A watershed is an area of land which drains to a common basin, such as a stream or river. Surface water, through rain or melting snow, tends to pick up contaminants as it flows untreated through a watershed directly into streams and rivers creating non-point source pollution. Most sources of point-pollution such as factories have been regulated and stormwater is the leading cause of water pollution today. Preventing this stormwater pollution entering our rivers and streams is of critical importance to our community and our habitats. Everyone can make small changes that will make a big difference!

Slow It Down, Spread It Out, Soak It In

What You Can Do to Prevent Stormwater Pollution

Disposal of Yard Waste

Dumping yard waste into storm drains or waterways adds excess nutrients to the water. Build healthy soil by recycling organic material for plant growth by using natural compost as opposed to chemical fertilizer. Many gardeners maintain their own compost pile. The City of Defiance also has programs for composting and leaf collection for City residents. More information can be found in this Home Composting Guide (PDF) or at the City Composting Site.


Try organic or non-toxic fertilizer as an alternative to chemicals. The runoff of chemicals from fertilizers, herbicides and pesticides is a major cause of non-point source pollution. Follow the instructions carefully, apply only the recommended amount and use these products as sparingly as possible by spot treating problem areas. Soil testing can provide information for proper nutrient application and reduce fertilizer use, reducing pollution and saving money. Check the weather forecast to avoid having to repeat the application.