What is Stormwater?

Stormwater is referred to as “non-point source” pollution because you can’t determine the exact source of the pollutants. “Point source” pollution, on the other hand, can be readily identified (i.e., a factory discharging chemical through a pipe). To make matters worse, stormwater does not go into the sewer where it can be filtered. Instead, pollutants can be flushed directly into waterways causing detrimental effects on the environment and water quality.

According to the U.S. Environmental Protection Agency, “Stormwater runoff is generated from rain and snowmelt events that flow over land or impervious surfaces, such as paved streets, parking lots, and building rooftops, and does not soak into the ground. The runoff picks up pollutants like trash, chemicals, oils, and dirt/sediment that can harm our rivers, streams, lakes, and coastal waters.” In urban areas, after long dry periods rainwater runoff can contain heavy accumulations of pollutants that have built up over time. In more natural areas including forests and wetlands, stormwater can soak into the ground, or be stored and filtered. (If you’ve ever seen someone wash their car on the grass, and thought “how weird”, it’s actually not. They are washing the pollutants off their car directly to the ground where they can be filtered.)

Typical stormwater runoff pollutants include:

  • Fertilizer
  • Pesticides/Herbicides
  • Heavy Metals
  • Oil and grease
  • Bacteria/viruses
  • Sediment
  • Construction Waste
  • Trash

View the video below produced by Silver Creek High School media students and Thriving Iris Productions to bring awareness to nonpoint source pollution.

How do impervious surfaces affect stormwater?

Impervious (does not allow liquid to pass through it) surfaces such as roads, parking lots, and roofs, which come with urban development, significantly change natural water flow patterns and the recharge of groundwater supplies.

Groundwater is the water found underground in the cracks and spaces in soil, sand and rock. It is stored in and moves slowly through geologic formations of soil, sand and rocks called aquifers. Why worry about groundwater?

  • Groundwater supplies drinking water for 51% of the total U.S. population and 99% of the rural population.
  • Groundwater helps grow our food. 64% of groundwater is used for irrigation to grow crops.
  • Groundwater is an important component in many industrial processes.
  • Groundwater is a source of recharge for lakes, rivers, and wetlands.

When rainfall cannot soak into the ground through impervious surfaces, not only is groundwater not recharged, but many other problems result: the amount and speed of water entering rivers and other water bodies increases causing the severity and frequency of floods to increase; the habitat for fish and other aquatic species is displaced and destroyed; and a decrease in base flows in our streams and water in our aquifers is seen.

What are the effects of polluted water?

Fast-moving polluted runoff (by-passing a filtering system as we’ve said) can flow into our rivers and streams, or overwhelm local infrastructure and cause sewage overflows. The health and environmental impact of sewage overflows is tremendous: our waters are polluted with pathogens, excess nutrients, heavy metals, and other toxins; aquatic life is killed and algal blooms are created that can suffocate fisheries; pathogens (disease-causing microorganisms that cause diarrhea, vomiting, respiratory, and other infections, hepatitis, dysentery, and other diseases) can end up in our drinking water supplies and swimming areas.

“I recognize the right and duty of this generation to develop and use the natural resources of our land but I do not recognize the right to waste them, or to rob by wasteful use, the generations that come after us.” 

~Theodore Roosevelt

How should we manage stormwater?

Traditionally, our water infrastructure— such as storm drains and culverts — has dealt with precipitation as something to get rid of rather than to protect. Storm drains and pipes channel rainfall and snowmelt into receiving waters, often far from its place of origin, losing groundwater recharge, reducing base flows in streams, increasing flooding, and lowering water quality as they do.

Recently, a more forward way of thinking considers natural methods of water management, replacing the pipes and drains, and having benefits to the environment and economy. These natural approaches include:

  • Using soil and vegetation in a constructed technique, such as rain gardens or green roofs, to mimic natural hydrologic processes like percolation through soil and plant uptake and transpiration.
  • Preserve natural features, such as floodplains with a natural vegetation buffer along streams that can slow, filter, and store polluted runoff.
  • Minimize or disconnect impervious surfaces (such as pavement), using methods such as rain barrels, narrower streets and permeable paving.

These techniques protect the natural water cycle by slowing or infiltrating precipitation rather than sending it directly into storm sewers or nearby streams. These approaches, when used properly, help maintain a more natural watershed, which in turn keeps our rivers clean and our communities healthy.

What is being done in Indiana to control stormwater?

Indiana’s efforts to clean up the waters in the State have been going on for a long while now. Beginning with the Stream Pollution Control Law of 1943, followed by the Clean Water Act of 1972, limits have been placed on the amount of pollutants that may be discharged into the waters of the State. These limits are set at levels protective of both the aquatic life in the waters which receive the discharge and protective of human health.

In 1990, EPA tightened the rules, and set up a basic stormwater control program for states to adopt, known as the National Pollutant Discharge Elimination System (NPDES) Permit Program. “Phase I” of this program regulated:

  • Construction activities that disturbed 5 or more acres.
  • Industrial activities depending on their pollutant potential
  • Municipal activities serving over 100,000 people

In 1999, the EPA implemented “Phase II” of the NPDES program, and published new regulations that covered:

  • Construction activities disturbing one (1) or more acres of land area.
  • Incentives for facilities to protect their operations from stormwater exposure.
  • Municipalities with less than 100,000 people.

As a result of regulating construction activities, communities would benefit with:

  • Improved water quality
  • Safer waters for boating, swimming and fishing.
  • Reduced local drinking water treatment costs.
  • Fewer recreational beach closures.
  • A more desirable environment in which to live.

What’s happening in Indiana as a result of Phase II?
Indiana established a Municipal Separate Storm Sewer System Program (MS4 Program), based on Phase II of the EPA’s NPDES stormwater regulations. Under this program, communities are required to apply for and obtain a NPDES permit. The permit requires them to develop a stormwater management plan and to implement best management practices (stormwater pollution prevention measures).

The MS4 regulations apply to any entity that discharges into the waters of Indiana and that owns and/or operates a stormwater conveyance that is separate and not connected to a publicly owned treatment works or part of a combined sewer system. This covers not only cities and towns, but also public entities such as universities, military bases, and departments of transportation. By the way, a conveyance is just that – a means of conveying or carrying water flow such as:

  • Roads with drainage systems
  • Municipal streets
  • Catch basins (curbside openings)
  • Curbs
  • Gutters
  • Ditches
  • Channels
  • Storm drains

What’s happening in Clark County?
The municipalities of Jeffersonville, Sellersburg, Clark County (as a whole), and Clarksville all fall under the new Phase II and MS4 regulations. In order to comply with program requirements, these communities will be:

  • Increasing public awareness of stormwater pollution.
  • Eliminating illegal connections and discharges to storm sewer systems.
  • Increasing sediment controls at construction sites.
  • Requiring controls in new development to remove pollutants from stormwater.
  • Improving pollution prevention from community facilities, such as maintenance garages, equipment areas, and work areas.

Details of the Phase II regulations can be found on the Indiana Department of Environmental Management (IDEM) – Office of Water Quality web site:

Homeowners – learn more about what steps you can take to reduce non-point source pollution.

Developers – find information on plan reviews, site inspections, and Qualified Professional Inspector (QPI) training.