The City of Westfield Storm Water Division is responsible for making sure our community complies with the Federal Clean Water Act by managing the storm water discharged from urbanized areas. Consistent with other State water programs, the cities' goal is to protect human health, aquatic life, and existing water resources. Storm water discharges, if uncontrolled, allow hazardous wastes such as pesticides, motor oil, and antifreeze to enter our waterways. Soil from erosion and other pollution that end up in streams, rivers, and lakes have a profound effect on our water quality. The Storm Water Division's responsibilities include roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels or storm drain.
Because impervious surfaces (parking lots, roads, buildings, compacted soil) do not allow rain to infiltrate into the ground, more runoff is generated than in the undeveloped condition. This additional runoff can erode watercourses (streams and rivers) as well as cause flooding after the stormwater collection system is overwhelmed by the additional flow. Because the water is flushed out of the watershed during the storm event, little infiltrates the soil, replenishes groundwater, or supplies stream baseflow in dry weather.
A first flush is the initial runoff of a rainstorm. During this phase, polluted water entering storm drains in areas with high proportions of impervious surfaces is typically more concentrated compared to the remainder of the storm. Consequently these high concentrations of urban runoff result in high levels of pollutants discharged from storm sewers to surface waters.
Pollutants entering surface waters during precipitation events is termed polluted runoff. Daily human activities result in deposition of pollutants on roads, lawns, roofs, farm fields, etc. When it rains or there is irrigation, water runs off and ultimately makes its way to a river, lake, or the ocean. While there is some attenuation of these pollutants before entering the receiving waters, the quantity of human activity results in large enough quantities of pollutants to impair these receiving waters.