There are a few key terms that need to be understood when it comes to a stormwater pollution prevention plan (SWPPP), and one of the most notable here is "impaired waters." What does this term actually mean, and why is it extremely important for both maintaining a safe jobsite and staying in compliance with local and federal regulations?

At Silver Leaf SWPPP, we're happy to assist Idaho clients with a wide range of SWPPP needs, from SWPPP inspections to dewatering, street sweeping and numerous other services. What exactly are we talking about when we refer to impaired waters, what are some of the pollutants that most often contribute to impaired waters, and which other factors impact this important area? Here's a general primer.

What Are Impaired Waters?

For those who are new to the SWPPP world and just learning about some of its ins and outs, the term impaired waters refers to any body of water identified by state or local authorities as containing pollutants or materials in excess of levels permitted by local, state and/or federal regulations. These pollutants can come from a variety of sources – some are naturally occurring, some are induced by human activity – but the result is the same: waters that don't meet drinking or recreational quality standards.

Not a Single Level to Consider

It's important to realize that the realm of impaired waters isn't typically defined by a single acceptable level of any given pollutant. Rather, the rating of impaired waters will also depend on how that body of water is being used.

For example, bodies that are used for swimming, fishing or other recreational activities, as well as sources used for drinking water will require much stricter standards than those not used for such purposes. This means that a body of water deemed impaired by one state may not be considered impaired in another due to the different regulations governing each area's usage.

This is perhaps the single area that most often gets glossed over or misunderstood when it comes to SWPPP. Knowing the regulations that govern each particular body of water is absolutely essential in order to ensure compliance.

Pollutants Contributing to Impaired Waters

The pollutants contributing to impaired waters can vary from state to state and region to region, but there are a few universal offenders:

  • Sediment runoff: This is the most common pollutant in impaired waters, and is caused by improperly managed stormwater runoff or untreated wastewater. A number of different forms of sediment can end up in impaired waters, and the most common are fine sediments such as silt and clay.
  • Heavy metals: This can either be naturally occurring or caused by human activities like mining, smelting, etc. Examples of heavy metals that have been known to turn up in impaired waters include mercury, lead, chromium and cadmium.
  • Organic compounds: Organic compounds, including oil and grease, can also find their way into impaired waters through runoff or sewer overflow.
  • Nutrients: Too much of a good thing can be bad in this case as well – nutrients like phosphorous and nitrogen are essential to keeping organisms healthy in our waterways, but too much of them can lead to an imbalance in the ecosystem and impair water quality.
  • Fertilizer: Used on both agricultural and residential properties, fertilizer can also lead to an influx of nutrients and impair water quality.

Other Factors Contributing to Impaired Waters

Of course, these are just the most common pollutants – there can be a wide variety of other sources that contribute to impaired waters. These include things like pathogens from animal waste, acid mine drainage, urban runoff and more.

It's also important to note that while the pollutants themselves are a key factor in determining how impaired a body of water is, there are other factors at play as well. These include things like temperature and dissolved oxygen levels, which can have an effect on the overall health of local ecosystems.

Impact of Drought on Impaired Waters

As many of our clients in both Idaho and especially Utah are well aware, droughts take place in both of these locations. Unfortunately, prolonged periods of drought can have a devastating impact on impaired waters.

When we experience a drought, surface water evaporates more quickly than it can be replenished, leaving behind an impermeable layer of dust and dirt. This layer serves to prevent rainfall or other sources of moisture from reaching the water table, which can cause a cascade of problems.

Additionally, when natural rainwater is scarce the water resources that do remain become more vulnerable to pollution from runoff and other sources. This means that even when it rains, the amount of water available isn't enough to dilute pollutants or replenish them back into healthier levels. This means higher levels of contaminants will be found in the water, which could lead to serious health and environmental issues.

In order to protect impaired waters during a drought, it is essential that all sources of pollution are kept under control. This means taking extra steps like using alternative watering methods for construction sites, using sediment fencing and turbidity curtains to prevent runoff from entering waterways, and ensuring that all wastewater is properly treated.

In conclusion, impaired waters are a serious environmental issue that must be taken seriously. It's important to understand what the term means and what the contributing factors are so that we can take the necessary steps to protect our water resources. Additionally, it's essential to keep an eye on how drought conditions can affect water quality, as this can have a tremendous impact on ecosystems.

For more here, or to learn about any of our Idaho SWPPP services and solutions, speak to our team at Silver Leaf SWPPP today.

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