Learn About Stormwater

Stormwater Key Definitions:

Channel is a long, narrow excavation or surface feature that conveys surface water and is open to the air. Channels may be constructed or natural. 

Clean Water Act is federal environmental law that includes the management of stormwater. Learn more about the Clean Water Act on the Environmental Protection Agency's website.

Detention means the temporary storage of stormwater runoff in a stormwater detention facility for the purpose of controlling the peak discharge.
 
Detention facility means a facility that collects water from developed areas and releases it at a slower rate than it enters the collection system. The excess of inflow over outflow is temporarily stored in a pond, tank, or vault and is typically released over a few hours or a few days.
 
Detention Pond is a structure to which stormwater runoff is directed, held for a period of time (detained), and slowly released to a surface water body. A dry pond is not designed to permanently contain water.
 
Erosion is a process that moves material, especially soil, from one location to another. Erosion is caused by the action of wind, water, or other forces working on the earth’s surface.
 
Impervious surface means a surface composed of any material that significantly impedes or prevents the natural infiltration of water into soil. Impervious surfaces include, but are not limited to, rooftops, buildings, streets and roads, and any concrete or asphalt surface.
 
Municipal Separate Storm Sewer System (MS4) is a storm system that flows through its own set of pipes rather than being combined with the sewer system. Johns Creek has its own storm system that discharges into streams, lakes, and rivers.
 
Sediment means solid material, both organic and inorganic, that is in suspension, is being transported or has been moved from its site of origin by air, water, ice or gravity as a product of erosion.
 
Sedimentation means the process by which eroded material is transported and deposited by the action of water, wind, ice or gravity.
 
Stormwater management facility means any infrastructure that effects stormwater management and which controls or conveys stormwater runoff.
 
Stormwater conveyance is a series of inlets and pipes (typically underground) used to collect and convey stormwater to a discharge point such as a stream, river, lake, detention/retention pond or other waterbody.
 
Stormwater runoff means the flow on the surface of the ground, resulting from precipitation.
 
Stormwater structure typically accounts for structures that make up components of stormwater facilities, such as catch basins, headwalls, culverts, and inlets.
 
Swale is a broad, shallow, gently sloped channel for conveying stormwater runoff.
 
Retention Pond is a stormwater control structure with a permanent pool of water in which stormwater runoff is directed. Runoff from each storm is retained, allowing suspended sediment particles and associated pollutants to settle out.
 
Riprap is a facing layer or protective mound of stones placed to prevent erosion or sloughing of a structure or embankment due to the flow of surface and storm water runoff. More information regarding regulation of riprap by the GA EPD can be accessed by following this link - https://epd.georgia.gov/document/publication/minor-land-disturbing-guidance-revised-4-5-17docx/download.