Port Perry Stormwater Management Plan
What is a stormwater management plan?
Stormwater management plans provide a mechanism whereby agencies, stakeholders and the general public can develop solutions that mitigate the impact of stormwater runoff on the environment.
Urban areas can greatly impact the water cycle by contributing pollutants to water systems, with a significant proportion of these contaminants coming from stormwater runoff. Urban stormwater can be defined as rainfall and snowmelt that seeps into the ground or runs overland into storm sewers, streams or lakes. It may also include runoff from activities such as watering lawns, washing cars and draining pools.
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Effects of Development on Runoff and the Hydrological Cycle (From: Understanding Stormwater Management, MOE 2007) |
In urban areas, large areas of hard surfaces such as asphalt and concrete prevent the natural transfer of water from the surface into the ground causing the water cycle to be interrupted. As such, stormwater often flows overland until it enters storm sewer pipes, swales and ditches, to be drained into lakes and rivers. As the stormwater flows over surface routes like parking lots and roads it picks up contaminants, which are subsequently flushed into the sewer system, eventually ending up in rivers and lakes. Examples of contaminants include oil and metals, sediments, chlorides, nitrates and phosphorous.
In the past, stormwater was drained to lakes and rivers directly. Now, however, upon knowing the implications of this practice, a standard engineering approach is to treat stormwater before it enters the lake and river systems through management controls such as filter systems, infiltration trenches and quality and quantity control ponds.
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