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Illicit Discharges

The Texas Commission on Environmental Quality ("TCEQ") regulates known discharges of contaminants to surface waters in the state of Texas. In an effort to address this type of pollution, stormwater management regulations were established to reduce the impact of contaminated stormwater runoff from certain MS4s. Under the regulations outlined in 40 CFR 122.26(b)(8), the District is required to comply with these requirements.

As a condition of the stormwater regulations, regulated MS4s are required to prohibit illicit discharges. An illicit discharge is any discharge to the District's storm sewer system that is not composed entirely of stormwater with the exceptions of State recognized exclusions or activities covered by a specific discharge permit. Examples of illicit discharges include overland drainage from car washing or cleaning paint brushes in or around a catch basin.

As part of the District's commitment to environmental stewardship, all illicit discharges to the District's stormwater system are prohibited, as set forth in the District's Rate Order, and the District has the legal authority to carry out inspection surveillance and monitoring procedures to comply with this policy

No District public service employee, visitor, resident, business, commercial or industrial facility, contractor, or construction site personnel shall cause or allow discharges into the District's storm sewer drainage system which are not composed entirely of stormwater, except for the allowed discharges listed in Section B.

Prohibited discharges include but are not limited to: oil, anti-freeze, grease, chemicals, wash water, paint, animal waste, garbage, and litter.


Types and Sources of Illicit Discharges

Stormwater runoff contains pollutants that can harm human health, degrade water quality and aquatic habitat, and impair ecosystem functions. On its way to streams and other bodies of water, stormwater runoff accumulates pollutants such as oil, gas, and other hydrocarbons, heavy metals, deicers, pesticides, fine sediment, fertilizers, and bacteria, all of which can impair water quality. Runoff from fertilized lawns contributes excess nutrients to waterbodies, which can lead to algal blooms and in extreme cases, fish kill events due to low dissolved oxygen levels. Elevated fecal coliform levels impair water quality and can lead to restrictions on the use and enjoyment of natural resources, such as, shellfish beds and swimming areas. Other stormwater pollution of concern includes toxic contaminants, such as heavy metals and pesticides, which can originate from vehicles and businesses or from homeowner activities.

All of these pollutants have the potential to wash into receiving waterbodies during storm events. Understanding the sources of these pollutants and the impacts each pollutant has can help inform municipal planning and assist in identifying priority goals and objectives when managing stormwater. The following table summarizes common stormwater pollutants, their sources and potential impact.


Common Stormwater Pollutants, Sources and Impacts
Pollutants Sources Impacts
Sediments Construction sites; eroding stream banks; and vehicle/boat washing. Destruction of plant and fish habitat; transportation of attached oils, nutrients and other pollutants; increased maintenance costs, flooding.
Nutrients (phosphorus, nitrogen) Fertilizers; bird and pet waste; vehicle/boat washing; grey water; decaying grass and leaves; sewer overflows; leaking trash containers; leaking sewer lines. Increased potential for nuisance or toxic algal blooms, increased potential for hypoxia/anoxia (low levels of dissolved oxygen which can kill aquatic organisms).
Hydrocarbons (petroleum compounds) Vehicle and equipment leaks; vehicle and equipment emissions; pesticides, fuel spills; equipment cleaning; improper fuel storage and disposal. Toxic to humans and aquatic life at low levels.
Heavy metals Vehicle brake and tire wear; vehicle/equipment exhaust; batteries; galvanized metal; paint and wood preservatives; fuels; pesticides; and cleaners. Toxic at low levels; drinking water contamination.
Pathogens (Bacteria) Bird and pet wastes; sewer overflows; and damaged sanitary lines. Risk to human health leading to closure of shellfish areas and swimming areas; drinking water contamination.
Toxic Chemicals Pesticides, dioxins, Polychlorinated Biphenyls; spills; illegal discharges; and leaks. Toxic to human and aquatic life at low levels.
Debris/litter Improper waste disposal and storage; fishing gear; leaking rubbish containers; cigarette butts, littering. Potential risk to human and aquatic life and aesthetically displeasing.

SOURCE Modified from Illicit Discharge Detection and Elimination: A Guidance Manual for Program Development and Technical Assessments Center for Watershed Production, 2004, p. 12, Table 2.


The following connections are prohibited, except as provided in Section (B) below:

Any drain or conveyance, whether on the surface or subsurface, which allows any non-stormwater discharge, including but not limited to sewage, process water, waste water, or wash water, to enter the stormwater drainage system, and any connections to the storm drain system from indoor drains or sinks.

Allowed Non-Storm Water Discharges
The District adopted the Allowable Non-Stormwater Discharges identified in the TPDES General Permit No. TXR040000 for coverage of small (Phase II) municipal separate storm sewer systems (MS4s). The listing of Allowable Non-Stormwater Discharges, as specified in Part II.C of the permit, includes the following discharge types:

  1. Water line flushing (excluding discharges of hyperchlorinated water, unless the water is first dechlorinated and discharges are not expected to adversely affect aquatic life);
  2. Runoff or return flow from landscape irrigation, lawn irrigation, and other irrigation utilizing potable water, groundwater, or surface water sources;
  3. Discharges from potable water sources that do not violate Texas Surface Water Quality Standards;
  4. Diverted stream flows;
  5. Rising ground waters and springs;
  6. Uncontaminated ground water infiltration;
  7. Uncontaminated pumped ground water;
  8. Foundation and footing drains;
  9. Air conditioning condensation;
  10. Water from crawl space pumps;
  11. Individual residential vehicle washing;
  12. Flows from wetlands and riparian habitats;
  13. Dechlorinated swimming pool discharges that do not violate Texas Surface Water Quality Standards;
  14. Street wash water excluding street sweeper waste water;
  15. Discharges or flows from emergency fire fighting activities (fire fighting activities do not include washing of trucks, run-off water from training activities, test water from fire suppression systems, and similar activities);
  16. Other allowable non-stormwater discharges listed in 40 CFR ยง 122.26(d)(2)(iv)(B)(1);
  17. Non-stormwater discharges that are specifically listed in the TPDES Multi Sector General Permit (MSGP) TXR050000 or the TPDES Construction General Permit (CGP) TXR150000;
  18. Discharges that are authorized by a TPDES or NPDES permit or that are not required to be permitted; and
  19. Other similar occasional incidental non-stormwater discharges such as spray park water, unless the TCEQ develops permits or regulations addressing these discharges.

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