There are a few terms that signal possible concerns within a stormwater pollution prevention plan (SWPPP), and "impaired waters" is one that's recognizable to any SWPPP professional. Impaired waters refer to those that have unacceptable levels of pollutants in them - which kinds of pollutants are commonly being referred to here, and why are they problematic?

At Silver Leaf SWPPP, we're here to assist clients around Utah with all their stormwater management needs, including SWPPP inspections, plan creation, street sweeping services and more. While there can be hundreds of different pollutants that contribute to impaired waters, a few stand out in terms of frequency and severity. Let's go over some of these most notable contaminants, why they cause impairment in waters, and what will often be done as part of your SWPPP setup to reduce their likelihood and impact.


Likely the single most common pollutant in this setting, sediment is created from construction sites and disturbed land areas that lack water runoff control. Sediment refers to any particles of soil, sand, clay or rock created as a result of human activity.

While it may not seem like a big deal on its own, large amounts of sediment can drastically affect water quality by blocking sunlight and oxygen needed for fish and other aquatic life. Not only that, but it can clog pipes, fill in channels and impair recreational activities like swimming or fishing.

As such, sediment control is a major priority when creating any stormwater pollution prevention plan. This usually means incorporating solutions such as silt fencing, sediment basins, and stabilized construction entrances.


Excessive nutrients such as nitrates and phosphorous can be introduced to waters through human activities like agricultural runoff or sewage overflow events. These can lead to algal blooms that deplete oxygen supplies in the water, leading to fish kills and other serious ecological impacts.

Common solutions for nutrient control involve incorporating various buffers such as buffer strips, stormwater wetlands or rain gardens into your plan. These can reduce the amount of runoff entering a body of water, helping to limit nutrient loading and the potential for algal blooms.

Road Pollutants

When performing construction work on or near any roadway, certain additional pollutants may contribute to impaired waters. These include:

  • Road salt: Used to treat snow and ice build-up on roads, road salt can be particularly problematic in waterways as it doesn’t evaporate like it does with snow. It can lead to salinization, or an increase of the amount of salts present in a body of water.
  • Oil and other hydrocarbons: This is another common pollutant resulting from road runoff. It can originate from cars, trucks and other motorized vehicles that pass through the area.
  • Grease: Again, this usually originates from vehicles. It can leave a slick coating on the surface of the water, preventing it from absorbing oxygen and light.

Substances That Consume Oxygen

In other cases, certain pollutants may be introduced that directly consume oxygen in the water. These include:

  • Wastewater from industrial discharges: This is often composed of organic wastes which can reduce levels of dissolved oxygen in a body of water, making it difficult for aquatic life to survive.
  • Excess organic materials from lawns and gardens: Leaves, grass clippings, and other organic materials can accumulate in waterways. As they decompose, they use oxygen which can cause serious issues for the aquatic environment.

Chemical Runoff

There are also several ways that chemical runoff can contribute to impairment. This includes:

  • Pesticides and herbicides: These are used in agricultural settings or on residential lawns and gardens. When not managed properly, they can lead to increased levels of certain chemicals in a body of water which can cause impairment.
  • Heavy metals: Heavy metals can be introduced through industrial sites and manufacturing processes. In high concentrations, they can cause serious damage to aquatic life or even human health.
  • In order to prevent impairment of local waters, it’s important to have a robust stormwater pollution prevention plan that includes measures for controlling each of these pollutants. Disinfectants: Anytime wastewater is discharged into a water body, there’s the potential for bacteria and other contaminants to be introduced. To prevent this from happening, it’s important to include measures such as disinfection or chemical clarification in your plan.

Fecal Coliform Bacteria

Finally, while not as common, it’s important to be aware of fecal coliform bacteria. This can originate from animal or human waste and lead to serious health issues if introduced into water supplies. It’s important to include monitoring for this type of pollutant in any plan.

Impaired waters are a serious concern that can lead to serious ecological and health issues. By understanding the sources of these pollutants, their effects on local waters, and ways to mitigate them through a stormwater pollution prevention plan, it’s possible to help keep our waterways healthy and safe for everyone to enjoy.

At Silver Leaf SWPPP, we understand the importance of protecting our local water from pollutants. Our team is highly experienced in helping you create an effective stormwater pollution prevention plan that includes measures to reduce and control these contaminants. Contact us today to learn more about our services for clients around Utah.

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