Water Quality

Stormwater management is essential for preventing soil erosion and flooding of inhabited areas. It is also vital in ensuring safe drinking water resources. In this section, access information on stormwater management and water quality. Learn all about incorporating and maintaining green infrastructures, investigating stream health, and creating an infiltration surface. Tips on green roofs, rainwater cisterns, and live staking can be found as well.

Stormwater Management, Flood Control, and Water Quality

Stormwater is rainwater that runs off roofs, lawns, and driveways and enters storm drain inlets. Along its way, stormwater can pick up various pollutants, such as fertilizers and pesticides. As it’s usually piped directly into local streams and rivers without any treatment, stormwater can lead to waterway pollution. In turn, polluted runoff can have a direct impact on drinking and residential water quality.

Increased stormwater runoff – along with impermeable surfaces in urban areas – can further lead to significant property damage and floods. This is why, over the past decade, stormwater management efforts have focused on improving the runoff’s quality. One way of accomplishing this is by directing the site runoff to low impact development practices.

Infiltration is among the most effective management practices for improving stormwater quality. It involves infiltrating stormwater into the soil or passing it through a soil/media mix such as compost or mulch. Infiltration allows stormwater to become part of the soil-water matrix, where microbes can break down organic forms of carbon and nitrogen. Also, the soil helps remove sediment, pathogens, and other particulates from the stormwater.

Other ways to control the movement of stormwater runoff and keep waterways clean include growing riparian buffers, implementing green infrastructure practices, and planting vegetated swales.

Stormwater Pollutants

As stormwater does not undergo any treatment, it can easily carry harmful materials into streams, rivers, ponds, wetlands, and other waterways. In general, stormwater pollutants are grouped into five main categories – sediment, solid waste, nutrient-rich materials, pathogens, and toxic materials.

Sediment is the largest volume pollutant. It typically comes from soil erosion and is most prominent in construction site runoff. The source of sediment pollution, however, can be any soil that is not protected from rainfall or runoff. Sediment poses a great water quality risk as it often carries other pollutants, such as bacteria, nutrients, and organic chemicals.

Other major stormwater pollutants include nitrogen and phosphorus. These nutrients can cause plant blooms in streams and rivers, including harmful algae blooms. Nutrient-rich pollutants also lower oxygen levels in state waterways, causing harm to fish and other aquatic life. Common sources include excess fertilizer applications and eroded soil.

Tips and Advice on Stormwater Quality

On this page, discover Penn State Extension resources on improving water quality, protecting water supplies, and keeping contaminants out of waterways. Gain a deeper understanding of common water pollutants through webinars on topics such as nitrates in private water supplies and iron, manganese, and hydrogen sulfide water quality issues.