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 Virginia Administrative Code (Last Updated: January 10, 2017)
 Title 9. Environment
 Agency 25. State Water Control Board
 Chapter 260. Water Quality Standards

  Section 170. Bacteria; other recreational waters  

Latest version.

  • A. The following bacteria criteria (colony forming units (CFU)/100 ml) shall apply to protect primary contact recreational uses in surface waters, except waters identified in subsection B of this section:

    E. coli bacteria shall not exceed a monthly geometric mean of 126 CFU/100 ml in freshwater.

    Enterococci bacteria shall not exceed a monthly geometric mean of 35 CFU/100 ml in transition and saltwater.

    1. See 9VAC25-260-140 C for boundary delineations for freshwater, transition and saltwater.

    2. Geometric means shall be calculated using all data collected during any calendar month with a minimum of four weekly samples.

    3. If there are insufficient data to calculate monthly geometric means in freshwater, no more than 10% of the total samples in the assessment period shall exceed 235 E. coli CFU/100 ml.

    4. If there are insufficient data to calculate monthly geometric means in transition and saltwater, no more than 10% of the total samples in the assessment period shall exceed enterococci 104 CFU/100 ml.

    5. For beach advisories or closures, a single sample maximum of 235 E. coli CFU/100 ml in freshwater and a single sample maximum of 104 enterococci CFU/100 ml in saltwater and transition zones shall apply .

    B. The following bacteria criteria per 100 ml (CFU/100 ml) of water shall apply:

    E. coli bacteria shall not exceed a monthly geometric mean of 630 CFU/100 ml in freshwater.

    Enterococci bacteria shall not exceed a monthly geometric mean of 175 CFU/100 ml in transition and saltwater.

    1. See 9VAC25-260-140 C for boundary delineations for freshwater, transition and saltwater.

    2. Geometric means shall be calculated using all data collected during any calendar month with a minimum of four weekly samples.

    3. If there is insufficient data to calculate monthly geometric means in freshwater, no more than 10% of the total samples in the assessment period shall exceed 1173 E. coli CFU/100 ml.

    4. If there is insufficient data to calculate monthly geometric means in transition and saltwater, no more than 10% of the total samples in the assessment period shall exceed 519 enterococci CFU/100 ml.

    5. Where the existing water quality for bacteria is below the geometric mean criteria in a water body designated for secondary contact in subdivision 6 of this subsection that higher water quality will be maintained in accordance with 9VAC25-260-30 A 2.

    6. Surface waters designated under this subsection are as follows:

    a. (Reserved)

    b. (Reserved)

    c. (Reserved)

Historical Notes

Derived from VR680-21-02.2, eff. May 20, 1992; amended, Volume 14, Issue 04, eff. December 10, 1997; Volume 19, Issue 07, eff. January 15, 2003; Volume 20, Issue 09, eff. February 12, 2004; Volume 26, Issue 12, eff. February 1, 2010.

Statutory Authority

§ 62.1-44.15 of the Code of Virginia; 33 USC § 1251 et seq. of the federal Clean Water Act; 40 CFR Part 131.