Dearborn County, Indiana
A unique mixture of agriculture and industrial enterprises with easy access to surrounding areas
What is an MS4?
A Municipal Separate Storm Sewer System, or MS4, is defined by the Indiana Department of Environmental Management as "a conveyance or system of conveyances owned by a state, city, town, or other public entity that discharges to waters of the United States and is designed or used for collecting or conveying stormwater. Regulated conveyance systems include roads with drains, municipal streets, catch basins, curbs, gutters, storm drains, piping, channels, ditches, tunnels, and conduits. It does not include combined sewer overflows and publicly owned treatment works."
The History Behind Federal Water Regulations
In 1948 the Federal Water Pollution Control Act was created with the goal to "enhance the quality and value of our water resources and to establish a national policy for the prevention, control, and abatement of water pollution". The act was later amended in 1956 and again in 1965 to include enforcement provisions.
In 1970 the United States Environmental Protection Agency was established, and the Clean Water Act was created.
In 1972 the Clean Water Act was amended to include enforceable permit requirements for point sources of pollution. The goal of the Clean Water Act is to "restore and maintain the chemical, physical, and biological integrity of America's waters".
A pollutant is defined by the Clean Water Act as: dredged soil, solid waste, incinerator residue, filter backwash, sewage, garbage, sewage sludge, munitions, chemical wastes, biological materials, radioactive materials (with the exception of those regulated under the Atomic Energy Act), heat, wrecked or discarded equipment, rock, sand, cellar dirt, industrial waste, agricultural waste, municipal waste discharged into water.
A point source is defined as any discernible, confined and discrete conveyance including but not limited to any pipe, ditch, channel, tunnel, conduit, well, discrete fissure, container, rolling stock, concentrated animal feeding operation, vessel or other floating craft, from which pollutants are or may be discharged.
In 1987 storm water became recognized as a conditionally regulated point source under the Clean Water Act. National Pollutant Discharge Elimination System Permits began to be developed for certain industrial activities, construction sites greater than 5 acres, and municipalities with populations greater than 100,000.
In 1992 the Individual MS4 Permit was created for municipalities with populations greater than 100,000 people. This was Phase I.
In 1999 the MS4 General Permit was created for municipalities with populations greater than 50,000 but less than 100,000 based on specific designation criteria. This was Phase II. For additional information regarding designation criteria click here.
Is Dearborn County an MS4?
The designation of MS4s is determined by the US Census data. In 2020 the US Census was conducted. Following the results in April of 2022, Dearborn County, along with Lawrenceburg, Greendale, and Aurora received letters from the Indiana Department of Environmental Management notifying the municipalities of their statuses as newly designated MS4s.
Newly Designated MS4 email from IDEM 7102023.docx
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