Quantity + Quality
The two fundamental characteristics of stormwater are water quantity and water quality.
Water quantity is the volume of water that leaves the site during or after a storm event, which can include surface runoff, infiltration, and groundwater recharge. Well designed SCMs systems provide temporary storage, promote infiltration, and release stormwater at a rate close or equal to the pre-developed conditions of the site.
Water quality measures the chemical, biological, and physical composition of runoff. Any pollutants or contaminants that are dissolved or suspended in stormwater can impact ecosystems and pose a threat to human health. The treatment elements of a well maintained SCM system will filter and improve the water quality before it leaves the site.