Receiving waters are natural or man-made surface water bodies that receive stormwater discharges from drainage systems, outfalls, or other conveyance structures. In stormwater management, the term refers to the ultimate destination of runoff after it has been collected and conveyed through systems such as ditches, swales, pipes, or a municipal separate storm sewer system (MS4).
Receiving waters include a wide range of water bodies, such as streams, rivers, lakes, ponds, wetlands, estuaries, and coastal waters. These systems serve as the endpoint for stormwater flows and are directly affected by the quantity and quality of the discharged runoff.
Because stormwater is often discharged to receiving waters without treatment, these water bodies are particularly vulnerable to pollution. Runoff can carry sediment, nutrients, metals, hydrocarbons, pathogens, and other contaminants generated from urban, agricultural, and construction activities. As a result, the condition of receiving waters is a primary concern in stormwater management and regulatory programs, including those established under the National Pollutant Discharge Elimination System.
The concept of receiving waters is central to water quality protection because it defines where impacts occur. Regulatory standards, such as water quality criteria and total maximum daily loads (TMDLs), are often established based on the condition and designated uses of receiving waters, including drinking water supply, recreation, and aquatic habitat.
Effective stormwater management aims to minimize adverse impacts to receiving waters by reducing pollutant loads, controlling runoff volumes and peak flows, and implementing treatment practices before discharge. Protecting receiving waters is a fundamental objective of watershed planning and environmental regulation.