Education Outreach

Stormwater Public Education, Outreach and Involvement

Why be concerned about Stormwater?

Why be concerned about Stormwater? Stormwater runoff can have a number of impacts. As development and imperviousness increase in an area, the natural capacity of the soil and vegetation to infiltrate and take up rainfall decreases, and more rainfall becomes stormwater runoff. This can produce negative impacts by causing erosion of land areas and stream banks, by causing or increasing flooding and also by carrying pollutants to surface waters. As Willoughby grows, development increases. When more houses, roads and businesses are constructed, water has nowhere to go and can cause serious drainage, pollutant, and sanitation problems. The following diagram demonstrates how development can cause:

• Increased Imperviousness
• Increased Runoff
• Increased Pollutants
• Impact to Streambanks
• Erosion/Sedimentation

Pollutants Commonly Found in Stormwater Runoff and Their Impacts
The Table below summarizes common stormwater pollutants and also provides information on potential sources of these pollutants and types of impacts they may cause.

Sediment	Sediment is often viewed as the largest pollutant load associated with stormwater runoff in an urban setting. The loadings have been shown to be exceptionally high in the case of construction activity. Sediment is associated with numerous impacts in surface waters including increased turbidity, effects on aquatic and benthic habitat and reduction in capacity of impoundments. A number of other pollutants often attach to, and are carried by, sediment particles.
Nutrients	The nutrients most often identified in stormwater runoff are phosphorus and nitrogen. In surface waters, these nutrient loads can lead to heavy algae growth, eutrophication (especially in impoundments) and low dissolved oxygen levels. Nutrients enter the urban system in a variety of ways, including landscaping practices (commercial and home), leaks from sanitary sewers and septic systems, and animal wastes.
Organic Matter	Various forms of organic matter may be carried by stormwater in urban areas. Decomposition of this material by organisms in surface waters results in depleted oxygen levels. Low levels of dissolved oxygen severely impact water quality and life within surface waters. Sources of organic matter include leaking septic systems, garbage, yard waste, etc.
Bacteria	High bacterial levels may be found in stormwater runoff as a result of leaking sanitary systems, garbage, pet waste, etc. The impacts of bacteria on surface waters may affect recreational uses and aquatic life as well as impose health risks.
Oil and Grease	Numerous activities in urban areas produce oil, grease, and lubricating agents that are readily transported by stormwater. The intensity of activities, including vehicle traffic, maintenance and fuelling activities, leaks and spills, and manufacturing processes within an urban setting contribute heavily to the level of these pollutants present in adjacent surface waters.
Toxic Substances	Many toxic substances are potentially associated with urban stormwater including metals, pesticides, herbicides and hydrocarbons. Toxic compounds may affect biological systems, and accumulate in bottom sediments of surface waters.
Heavy Metals	Heavy metals such as copper, lead, zinc, arsenic, chromium and cadmium may be typically found in urban stormwater runoff. Metals in stormwater may be toxic to some aquatic life and may accumulate in aquatic animals. Urban sources of metals in stormwater may include automobiles, paints, preservatives, motor oil and various urban activities.
Temperature	Stormwater runoff increases in temperature as it flows over impervious surfaces. In addition, water stored in shallow, unshaded ponds and impoundments can increase in temperature. Removal of natural vegetation (such as tree canopy) opens up water bodies to direct solar radiation. Elevated water temperatures can impact a water body’s ability to support certain fish and aquatic organisms.

How Stormwater Is Carried

Stormwater runoff may be carried through natural or manmade drainage ways or conveyance systems. In some cases stormwater runoff leaves a site spread out over a large dispersed area as “sheet flow.” It may also be conveyed through natural ditches, swales and natural drainage features. In most developing and urbanizing areas, stormwater is conveyed through a system of catch basins and pipes commonly referred to as a storm sewer system.