The following words and terms, when used in this subchapter, shall have the following meanings, unless the context clearly indicates otherwise.
  (1) Average quality--The arithmetic average (weighted by flow value) of all the daily determinations of concentrations made during a calendar month. Daily determinations of concentrations made using a composite sample shall be the concentration of the composite sample. When grab samples are used, the daily determination of concentration shall be the arithmetic average (weighted by flow value) of all samples collected during the calendar day.
  (2) Daily composite quality--The concentration of a sample consisting of a minimum of three grab samples of effluent collected at regular intervals over a normal operating day and combined proportional to flow, or a sample continuously collected proportional to flow over a normal operating day.
  (3) Grab sample quality--The concentration of an individual sample of effluent collected in less than 15 minutes.
  (4) Hazardous metal--Includes each of the following metals in its elemental state and any of its compounds expressed as that metal: arsenic, barium, cadmium, chromium, copper, lead, manganese, mercury, nickel, selenium, silver, and zinc.
  (5) Inland waters--All surface waters in the state other than tidal waters defined in this section.
  (6) Tidal waters--Those waters of the Gulf of Mexico within the jurisdiction of the State of Texas, bays and estuaries thereto, and those portions of the river systems which are subject to the ebb and flow of the tides, and to the intrusion of marine waters.

Source Note: The provisions of this §319.21 adopted to be effective July 2, 1986, 11 TexReg 2893.