City of Shepherdsville MS4 FAQ for Citizens

What Is a Municipal Separate Storm Sewer System (MS4)? An MS4 is defined as a system of publicly-owned conveyance(s), including roads, curbs, gutters, swales or ditches that discharge (outfalls) to surface waters of the Commonwealth. MS4 systems are designed or used solely for collecting or conveying stormwater. This stormwater is not routed to a wastewater treatment facility; it is directly discharged into local waterbodies. The term MS4 does not solely refer to publicly-owned storm sewer systems. Rather the term has a much broader application that can include, in addition to local jurisdictions, state departments of transportation, universities, local sewer districts, hospitals, military bases, and prisons. What is the MS4 Storm Water Program? EPA’s Stormwater Phase II Rule establishes an MS4 stormwater management program that is intended to improve the Nation’s waterways.  EPA hopes the rule will reduce the quantity of pollutants that stormwater picks up and carries into storm sewer systems during storm events. Common pollutants include oil and grease from roadways, pesticides from lawns, sediment from construction sites, and carelessly discarded trash, such as cigarette butts, paper wrappers and plastic bottles. When deposited into nearby waterways through MS4 discharges, these pollutants can harm the waterways, thereby  preventing recreational use of the resource, contaminating drinking water supplies, and impacting the habitat for fish, other aquatic organisms and wildlife In 1990, EPA established Phase I of the National Pollutant Discharge Elimination System (NPDES) stormwater program. In Kentucky, this program is known as the Kentucky Pollutant Discharge Elimination System (KPDES).  The Phase I program for MS4s requires operators of “medium” and “large” MS4s, that is, those that generally serve populations of 100,000 or greater, to implement a Stormwater Management Program.  The program is designed as a means to control polluted discharges from the MS4s. In Kentucky there are two Phase I MS4 programs; they are located in Louisville and Lexington. The Stormwater Phase II Rule extends coverage of the NPDES stormwater program to certain small MS4s. In Kentucky there are over 100 small Phase II programs. How Is A Small MS4 Designated as a Regulated Small MS4? A small MS4 can be designated by the permitting authority as a regulated small MS4 in one of three ways:

  • Automatic Nationwide Designation

The Phase II Final Rule requires nationwide coverage of all operators of small MS4s that are located within the boundaries of a Bureau of the Census-defined “urbanized area” (UA) based on the latest decennial Census. Once a small MS4 is designated into the program based on the UA boundaries, it cannot be waived from the program if in a subsequent UA calculation the small MS4 is no longer within the UA boundaries. An automatically designated small MS4 remains regulated unless, or until, it meets the criteria for a waiver. An urbanized area (UA) is a land area comprising one or more places – central place(s) – and the adjacent densely settled surrounding area – urban fringe – that together have a residential population of at least 50,000 and an overall population density of at least 1,000 people per square mile. It is a calculation used by the Bureau of the Census to determine the geographic boundaries of the most heavily developed and dense urban areas. EPA has developed a set of digitized maps for each urbanized area as defined by the 2000 U.S. Census. These maps are organized by state and are available at Additionally, information about urbanized areas is available directly from the U.S. Bureau of the Census at uaucbndy.html.

  • Potential Designation by the NPDES Permitting Authority – Required Evaluation

An operator of small MS4 located outside of a UA may have been designated as a regulated small MS4 if the NPDES permitting authority determined that its discharges cause, or have the potential to cause, an adverse impact on water quality. The Phase II Final Rule required the NPDES permitting authority to develop a set of designation criteria and apply them, at a minimum, to all small MS4s located outside of a UA serving a jurisdiction with a population of at least 10,000 and a population density of at least 1,000 people/square mile.  

Designation Criteria – EPA recommended that the NPDES permitting authority use a balanced consideration of the following designation criteria on a watershed or other local basis:
•   Discharge to sensitive waters;
•   High population density;
•   High growth or growth potential;
•   Contiguity to a UA;
•   Significant contributor of pollutants to waters of the United States and
•   Ineffective protection of water quality concerns by other programs
•   Potential Designation by the NPDES Permitting Authority – Physically Interconnected Under the final rule, the NPDES permitting authority was required to designate any small MS4 located outside of a UA that contributes substantially to the pollutant loadings of a physically interconnected MS4 regulated by the NPDES stormwater program. The final rule did not set a deadline for designation of small MS4s meeting this criterion. Physically interconnected means that one MS4 is connected to a second MS4 in such a way that it allows for direct discharges into the second system. State and EPA permitting authorities can be contacted to obtain a full list of regulated MS4s, including both automatically designated MS4s and those that were additionally designated.

What are the primary elements that are contained in a Stormwater Quality Management Plan (SWQMP)? The SWQMP includes minimum control measures that cover a broad spectrum of issues that are associated with stormwater runoff.  These measures include:

  • Public Education and Outreach
  • Public Participation and Involvement
  • Illicit Discharge Detection and Elimination
  • Construction Site Stormwater Runoff Control
  • Post-Construction Stormwater Management
  • Municipal Operations Pollution Prevention and Good Housekeeping

Why should I care? Do you know where your drinking water comes from?  In the Commonwealth, people get their water from streams, rivers, lakes and from groundwater.  Impervious surfaces, such as streets, sidewalks and parking lots cannot easily absorb water. When a pollutant is spilled on an impervious surface, it stays there until stormwater runoff washes it away. When it rains or snows, the water that runs off of land surfaces can wash sediment, oil, grease, toxins, pathogens and other pollutants into nearby water bodies. This water is normally discharged untreated into local surface water causing environmental impacts and reducing the quality of our drinking water. The pollutants associated with stormwater runoff can adversely affect the physical and biological health of Kentucky’s surface waters. Pollutants can reduce the recreational use of Kentucky’s waters and be detrimental to the habitat and diversity of aquatic organisms, fish and other wildlife. Pollutants in our water cause water treatment to be more costly, and can be bad for our health if we drink directly from the water source. Does my community have an MS4? Yes the City of Shepherdsville is a MS4 community. How can I help protect our local waterbodies? Ten easy ways you can make a difference in your community and to protect your local water resources:

  1. Don’t dump ANYTHING down storm drains. Oils, chemicals, soaps, etc. pollute our streams and lakes.
  2. Use pesticides and fertilizers sparingly and always follow label instructions.
  3. Put litter in its place (trash cans or recycling bins).
  4. Pick up after your pet.
  5. Sweep driveways (don’t spray wash) and dispose of the sweepings properly.
  6. Collect yard waste and keep it out of storm drains. Compost! Even grass clippings and excess leaves don’t belong in our streams and rivers.
  7. Use a commercial car wash (they treat and recycle wash water) or wash vehicles on grassy areas.
  8. Recycle used motor oil. Most auto parts retailers accept used motor oil for recycling.
  9. Check your car for leaks (and fix them).
  10. Have your septic tank inspected every 3 – 5 years by local septic tank companies to insure proper operation.