Storm Water


Introduction to Storm Water in Olmsted County

Within the Urbanized Area of Olmsted County, when rain falls or snow melts, the runoff washes off paved streets, driveways, parking lots, building rooftops, and lawns picking up sediment, metals, oil, grease, litter, bacteria, and other pollutants that threaten water quality. What most people don't realize is that this storm water runs into the County's road ditches, which drain into our rivers, lakes, and streams and this runoff is not treated in any way.


This type of runoff pollution is called non-point source pollution because it comes from many different sources spread across the landscape. The symptoms of non-point pollution are very recognizable: muddy streams that flood frequently, excessive weeds and algae in our lakes and rivers, and an over-abundance of rough fish in our favorite fishing spots. From farmlands to suburban lawns, people use the land in ways that jeopardize the quality of our water resources.


What Can You Do To Help Prevent Storm Water Pollution?

The first step toward keeping our rivers, lakes, and streams clean is to think about what we do on the land. Each of us contributes to storm water pollution and each of us can help prevent it. Here are some ways you can help:

  • Don't allow grass clippings, leaves, fertilizer, pet waste, or soil to wash off your property.
  • Test your soil and apply fertilizer at the correct rate.
  • If your property adjoins a drainageway or waterway, try to allow for a 15 to 20 foot "buffer" strip of unmowed grass along its edge (see Figure 1 above).
  • Divert roof water to lawns where it can soak in.

10 smart salting tips that protect Minnesota waters (28KB)

For more lawn and garden tips, check out the University of Minnesota Extension Service - Yard and Garden.

Keep your road ditch clean of debris and/or volunteer for the County's Adopt-a-Highway Program (for more information call Olmsted County Public Works at 507 328-7070)

Other Ways You Can Help

What is the County Doing?

In December 1999, the U.S. Environmental Protection Agency (EPA) issued regulations that placed Olmsted County on a list of communities that must comply with new federal storm water requirements (What is NPDES Phase II). Over the next several years, the County will be adopting new regulations and implementing new measures for controlling and treating storm water pollution.

In 2003, the County developed a Storm Water Pollution Prevention Plan that is designed to reduce the discharge of pollutants and protect water quality in the Rochester Urbanized Area (UA Map (160KB) ). The goal of the plan is to eliminate and minimize storm water contact with pollutants through the use of six minimum control measures:

  • Public education and outreach
  • Public participation and involvement
  • Illicit discharge detection and elimination
  • Construction site storm water runoff control
  • Post-construction storm water management
  • Pollution prevention and good housekeeping practices

This plan was last updated in 2006. Olmsted County is currently working to revise it's SWPPP.

Olmsted County's Storm Water Pollution Prevention Plan (2013-2018)

SWPPP-2013-2018 (578 KB) 

Illicit Discharge Ordinance adopted by County Board in December 2017 

To comply with the requirements of the National Pollutant Discharge Elimination System (NPDES) permit process, Olmsted County enacted an illicit discharge ordinance to establish methods for controlling the introduction of pollutants into the County Municipal Separate Storm Sewer System (MS4).

The purpose of this ordinance is to provide for the health, safety, and general welfare of the citizens of Olmsted County through the regulation of non-storm water discharges to the storm drainage system to the maximum extent practicable as required by federal and state law.

On December 20, 2017 the Illicit Discharge Ordinance was updated and approved by the Olmsted County Board to become effective on January 1, 2018.  This ordinance was updated to coincide with the Olmsted County Enforcement and Appeals Ordinance and reflects changes in how a notice of violation, denial of request for exception/challenge and of a suspension or revocation of County license or permit issued may be appealed.  The full context of the ordinance may be found here:  Chapter 3800 Illicit Stormwater Discharge Ordinance (64 KB) and additional information relating to the Enforcement and Appeals Ordinance may be found on Olmsted County's Attorney's page.