Stormwater is naturally occurring precipitation, and while some stormwater soaks into the ground, much of it turns into runoff and can pick up pollutants like chemicals, automotive fluids, sediment, and litter as it flows over various surfaces. Runoff is channeled into the Town of Paradise Valley’s Municipal Separate Storm Sewer System (MS4). The MS4 has many parts, including washes, catch basins, storm drains, curbs, inlets, scuppers, streets, gutters, retention basins, and any other Town-owned structure that conveys stormwater to waters of the US.
It is important to understand that the MS4 is separate from the sanitary sewer system. The sanitary sewer transfers waste water from residences and businesses directly to the Water Reclaimation Facility for treatment.
In contrast, the MS4 has no treatment process and empties its unfiltered contents directly into basins, drainages, and bodies of water, where it eventually infiltrates into the groundwater. This is why preventing stormwater pollution is so important. Stormwater remains unfiltered as it makes its way through the MS4, so whatever goes down the storm drain can eventually end up in our water supply.
Typical pollutants found in stormwater include trash, fertilizers, household detergents, pool water, pet waste, sediment, gasoline and petroleum products, and hazardous chemicals.