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25 Pa. Code § 93.1. Definitions.


§ 93.1. Definitions.

 The following words and terms, when used in this chapter, have the following meanings, unless the context clearly indicates otherwise:

   BMP—Best management practices

     (i)   Schedules of activities, prohibitions of practices, maintenance procedures and other management practices to prevent or reduce pollution to surface waters of this Commonwealth.

     (ii)   The term includes:

       (A)   Treatment requirements.

       (B)   Operating procedures.

       (C)   Practices to control plant site runoff, spillage, or leaks, sludge or waste disposal, or drainage from raw material storage.

   Carcinogen—A substance that causes an increased incidence in benign or malignant neoplasms, or a substantial decrease in the latency period between exposure and the onset of neoplasms in man or other species as evidenced by toxicological or epidemiololgical studies, or both.

   Class A wild trout water—A surface water classified by the Fish and Boat Commission, based on species-specific biomass standards, which supports a population of naturally produced trout of sufficient size and abundance to support a long-term and rewarding sport fishery.

   Clean Streams Law—The Clean Streams Law (35 P.S. § §  691.1—691.1001).

   Clean Water Act—The Federal Water Pollution Control Act (33 U.S.C.A. § §  1251—1376).

   Conventional treatment—For the purpose of surface water protection of the Potable Water Supply (PWS) use, coagulation, followed by filtration for the removal of solids, and disinfection for the control of pathogens to produce water for drinking and other human consumption.

   Coordinated water quality protective measures

     (i)   Legally binding sound land use water quality protective measures coupled with an interest in real estate which expressly provide long-term water quality protection of a watershed corridor.

     (ii)   Sound land use water quality protective measures include: surface or groundwater source protection zones, enhanced stormwater management measures, wetland protection zones or other measures which provide extraordinary water quality protection.

     (iii)   Real estate interests include:

       (A)   Fee interests.

       (B)   Conservation easements.

       (C)   Government owned riparian parks or natural areas.

       (D)   Other interests in land which enhance water quality in a watershed corridor area.

   Daily average—The arithmetic average of the samples collected during a continuous 24-hour period.

   Designated uses—Those uses specified in § §  93.4(a) and 93.9a—93.9z for each water body or segment whether or not they are being attained.

   Epilimnion—Warm upper layer of nearly uniform temperature in a stratified body of water, such as a lake or impoundment.

   Exceptional Value Waters—Surface waters of high quality which satisfy §  93.4b(b) (relating to antidegradation).

   Existing uses—Those uses actually attained in the water body on or after November 28, 1975, whether or not they are included in the water quality standards.

   Four-day average—The arithmetic average of the samples collected during a consecutive 4-day period.

   High Quality Waters—Surface waters having quality which exceeds levels necessary to support propagation of fish, shellfish, and wildlife and recreation in and on the water by satisfying §  93.4b(a).

   Hypolimnion—The cooler, denser, lower layer in a naturally stratified lake, pond or impoundment.

   Margin of safety—The combination of uncertainty and modifying factors applied to the results of toxicity tests to compensate for incomplete characterization of the effect on the population to be protected.

   Monthly average—The arithmetic average on the samples collected during a calendar month.

   Natural quality—The water quality conditions that exist or that would reasonably be expected to exist in the absence of human related activity.

   Nonpoint source—A pollution source which is not a point source discharge.

   Nonthreshold effect—An adverse impact, including carcinogenic effects, for which no exposure greater than zero assures protection to the exposed individual.

   One-hour average—The arithmetic average of the samples collected during a continuous 1-hour period.

   Osmotic pressure—The pressure which, when applied to a solution, will just prevent the passage of solvent—usually water—from an area of low solute concentration through a semipermeable membrane to an area of high solute concentration.

   Outstanding National, State, regional or local resource water—A surface water for which a National or State government agency has adopted water quality protective measures in a resource management plan, or regional or local governments have adopted coordinated water quality protective measures along a watershed corridor.

   Point source discharge—A pollutant source regulated under the National Pollutant Discharge Elimination System (NPDES) as defined in §  92a.2 (relating to definitions).

   Priority pollutants—The chemicals identified by the EPA for priority in water pollution control, under section 307(a)(1) of the Clean Water Act (33 U.S.C.A. §  1317(a)(1)).

   Risk assessment—The characterization of the potential adverse effects of exposure to environmental hazards. The term includes hazard identification, dose-response assessment, exposure assessment and risk characterization.

   Risk management—The process of evaluation and selection between alternative regulatory options. Risk management decisions may include consideration of risk assessment, analytical, socio-economic and political factors.

   Seven-day average—The arithmetic average of the samples collected during a consecutive 7-day period.

   State game propagation and protection area—An area established by the Game Commission for the propagation and protection of game or wildlife wherein game or wildlife may not be hunted, pursued, disturbed, molested, killed or taken at any time except as authorized by the Game Commission.

   Surface water of exceptional ecological significance—A surface water which is important, unique or sensitive ecologically, but whose water quality as measured by traditional parameters (for example, chemical, physical or biological) may not be particularly high, or whose character cannot be adequately described by these parameters. These waters include:

     (i)   Thermal springs.

     (ii)   Wetlands which are exceptional value wetlands under §  105.17(1) (relating to wetlands).

   Surface water of exceptional recreational significance—A surface water which provides a water-based, water quality-dependent recreational opportunity (such as fishing for species with limited distribution) because there are only a limited number of naturally occurring areas and waterbodies across the State where the activity is available or feasible.

   Surface waters—Perennial and intermittent streams, rivers, lakes, reservoirs, ponds, wetlands, springs, natural seeps and estuaries, excluding water at facilities approved for wastewater treatment such as wastewater treatment impoundments, cooling water ponds and constructed wetlands used as part of a wastewater treatment process.

   Threshold effect—An adverse impact that occurs in the exposed individual only after a physiological reserve is depleted. For these effects there exists a dose below which no adverse response will occur.

   Thirty-day average—The arithmetic average of the samples collected during a consecutive 30-day period.

   Toxic substance—A chemical or compound in sufficient quantity or concentration which is, or may become, harmful to human, animal or plant life. The term includes, but is not limited to, priority pollutants and those substances, which are identified in Tables 5 and 6. Additional toxic substances are also described in Chapter 16 Appendix A, Table 1A (relating to site-specific water quality criteria for toxic substances).

   WER—Water Effect Ratio—A factor that expresses the difference between the measures of the toxicity of a substance in laboratory water and the toxicity in site water. The WER provides a mechanism to account for that portion of a metal that is toxic under certain physical, chemical or biological conditions.

   Water quality criteria—Numeric concentrations, levels or surface water conditions that need to be maintained or attained to protect existing and designated uses.

   Wetlands—Areas that are inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions, including swamps, marshes, bogs and similar areas.

   Wilderness trout stream—A surface water designated by the Fish and Boat Commission to protect and promote native trout fisheries and maintain and enhance wilderness aesthetics and ecological requirements necessary for the natural reproduction of trout.


   The provisions of this §  93.1 amended under sections 5(b)(1) and 402 of The Clean Streams Law (35 P.S. § §  691.5(b)(1) and 691.402); section 1920-A of The Administrative Code of 1929 (71 P.S. §  510-20).


   The provisions of this §  93.1 amended May 30, 1980, effective May 31, 1980, 10 Pa.B. 2157; amended March 10, 1989, effective March 11, 1989, 19 Pa.B. 968; amended February 11, 1994, effective February 12, 1994, 24 Pa.B. 832; amended December 26, 1997, effective December 27, 1997, 27 Pa.B. 6799; amended July 16, 1999, effective July 17, 1999, 29 Pa.B. 3720; amended November 17, 2000, effective November 18, 2000, 30 Pa.B. 6059; amended February 11, 2005, effective February 12, 2005, 35 Pa.B. 1197; amended May 15, 2009, effective May 16, 2009, 39 Pa.B. 2523; amended July 19, 2013, effective July 20, 2013, 43 Pa.B. 4080; amended July 10, 2020, effective July 11, 2020, 50 Pa.B. 3426. Immediately preceding text appears at serial pages (384081) to (384082) and (367527) to (367529).

Cross References

   This section cited in 25 Pa. Code §  250.309 (relating to MSCs for surface water); 25 Pa. Code §  250.406 (relating to relationship to surface water quality requirements); 25 Pa. Code §  290.102 (relating to use as structural fill); 25 Pa. Code §  290.103 (relating to use as a soil substitute or soil additive); 25 Pa. Code §  290.105 (relating to beneficial use at abandoned mine lands); and 25 Pa. Code §  290.404 (relating to areas where coal ash storage is prohibited).

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