(a) Environmental Protection Agency (EPA) registration. A sanitizer, disinfectant, or other chemical used to treat the water shall be EPA-registered under the Federal Insecticide, Fungicide, and Rodenticide Act if it is a pesticide as defined by the EPA.
(b) NSF/ANSI listing. A non-pesticide chemical used to treat the water shall be listed and labeled to NSF/ANSI Standard 50 or NSF/ANSI Standard 60.
(c) Manufacturer's instructions. Chemicals shall be used according to the manufacturer's instructions.
(d) Required water quality. Unless the department has approved an alternate form of disinfectant, water quality shall meet the following criteria at all times the lagoon is open.
Attached Graphic
(e) Water clarity. Water clarity shall be sufficient such that an eight-inch black disk or Secchi Disk on the floor at the deepest part of the swimming areas of the lagoon can be clearly and immediately seen by an observer on the water surface above the disk or by someone standing on the shore closest to the disk.
(f) Swimming area testing frequency.
  (1) When a swimming area of a lagoon is open, tests for sanitizer levels (free available chlorine or bromine) and pH shall be made in each swimming area at least three times a day. One of the tests for sanitizer levels and pH shall be made before opening.
  (2) Test samples in a swimming area shall be taken where the water is a minimum of three feet in depth.
  (3) Alkalinity and calcium hardness testing frequency. Unless the department has approved an alternate method of disinfectant when a lagoon is open, tests for alkalinity shall be performed weekly and tests for calcium hardness shall be performed monthly in all swimming areas of the lagoon.
(g) Non-swimming area testing and frequency.
  (1) Unless the department has approved an alternate method of disinfectant when a non-swimming area of a lagoon is open, tests for sanitizer levels (free available chlorine, bromine) and pH shall be performed at least three times a day. One of the tests for sanitizer levels and pH shall be performed before opening.
  (2) Test samples in a non-swimming area of the lagoon shall be taken at a minimum of two locations located on opposite sides of the lagoon.
  (3) Alkalinity testing frequency. Unless the department has approved an alternate method of disinfectant when a lagoon is open, tests for alkalinity shall be performed weekly and tests for calcium hardness shall be performed monthly.
(h) ORP reading frequency. Readings shall be recorded at the same time sanitizer and pH tests are performed where in-line ORP meters are used.
(i) Reliable testing methods. A reliable means of testing for pH, free available chlorine, combined chlorine, cyanuric acid (if used), bromine, alkalinity, and calcium hardness, shall be maintained for the lagoon. The test method shall be capable of measuring chemical ranges as detailed in subsection (d) of this section.
(j) DPD chemical test. Free available chlorine levels shall be determined by the use of the DPD method or its equivalent.
(k) Storage of test kits and reagents. Test kits and reagents shall be stored according to the manufacturer's instructions and protected from extreme heat and cold and from exposure to water, chemicals, petroleum products or any other element or environment that could adversely affect the efficacy of water quality test results.
(l) Testing reagents. Testing reagents shall be changed at frequencies recommended by the manufacturer to ensure accuracy of the tests.
(m) Chemical balance. Unless an alternate method of disinfectant has been approved by the department, water in a lagoon shall be chemically balanced. Testing methods to determine the chemical balance of the water in the lagoon, such as the Langelier Saturation Index, shall be conducted once a week at a minimum.
(n) Operation record retention. Operational records, including results of required chemical testing under this section, shall be kept for three years and be made available during an inspection.
(o) Off-season chemical levels. When a lagoon is not in use for at least 30 days (such as off-season), clarity shall be maintained, and algae growth shall be prevented, however, other water quality parameters as required in this section need not be maintained.

Source Note: The provisions of this §265.166 adopted to be effective March 1, 2020, 45 TexReg 1024