Small MS4 General Permit TPDES General Permit TXR040000 Part I
Permittee - The MS4 operator authorized under this general permit.
Point Source - (from 40 CFR § 122.22) any discernible, confined, and discrete conveyance,
including but not limited to, any pipe, ditch, channel, tunnel, conduit, well, discrete fissure,
container, rolling stock, concentrated animal feeding operation, landfill leachate collection
system, vessel or other floating craft from which pollutants are or may be discharged. This term
does not include return flows from irrigated agriculture or agricultural stormwater runoff.
Pollutant(s) of Concern – For the purpose of this permit, includes biochemical oxygen
demand (BOD), sediment or a parameter that addresses sediment (such as total suspended
solids (TSS), turbidity or siltation), pathogens, oil and grease, and any pollutant that has been
identified as a cause of impairment of any water body that will receive a discharge from an MS4.
(Definition from 40 CFR § 122.32(e)(3)).
Redevelopment - Alterations of a property that changed the ”footprint” of a site or building in
such a way that there is a disturbance of equal to or greater than one (1) acre of land. This term
does not include such activities as exterior remodeling, routine maintenance activities, and
linear utility installation.
Semiarid Areas - Areas with an average annual rainfall of at least ten (10) inches, but less
than 20 inches.
Small Municipal Separate Storm Sewer System (MS4) – A conveyance or system of
conveyances (including roads with drainage systems, municipal streets, catch basins, curbs,
gutters, ditches, manmade channels, or storm drains):
(a) Owned or operated by the U.S., a state, city, town, borough, county, district,
association, or other public body (created by or pursuant to State law) having
jurisdiction over disposal of sewage, industrial wastes, stormwater, or other wastes,
including special districts under state law such as a sewer district, flood control district
or drainage district, or similar entity, or an Indian tribe or an authorized Indian tribal
organization, or a designated and approved management agency under CWA § 208;
(b) Designed or used for collecting or conveying stormwater;
(c) Which is not a combined sewer;
(d) Which is not part of a publicly owned treatment works (POTW) as defined in 40 CFR §
(e) Which was not previously regulated under a National Pollutant Discharge Elimination
System (NPDES) or a Texas Pollutant Discharge Elimination System (TPDES)
individual permit as a medium or large municipal separate storm sewer system, as
defined in 40 CFR §§122.26(b)(4) and (b)(7).
This term includes systems similar to separate storm sewer systems at military bases, large
hospitals or prison complexes, and highways and other thoroughfares. This term does not
include separate storm sewers in very discrete areas, such as individual buildings. For the
purpose of this permit, a very discrete system also includes storm drains associated with certain
municipal offices and education facilities serving a nonresidential population, where those
storm drains do not function as a system, and where the buildings are not physically
interconnected to a small MS4 that is also operated by that public entity.
Stormwater and Stormwater Runoff - Rainfall runoff, snow melt runoff, and surface
runoff and drainage.
Stormwater Associated with Construction Activity - Stormwater runoff from an area
where there is either a large construction or a small construction activity.