LIS

Virginia Law

Administrative Code

Creating a Report: Check the sections you'd like to appear in the report, then use the "Create Report" button at the bottom of the page to generate your report. Once the report is generated you'll then have the option to download it as a pdf, print or email the report.

Virginia Administrative Code
Title 9. Environment
Agency 25. State Water Control Board
Chapter 260. Water Quality Standards
11/23/2024

9VAC25-260-170. Bacteria; other recreational waters.

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

In freshwater, E. coli bacteria shall not exceed a geometric mean of 126 counts/100ml and shall not have greater than a 10% excursion frequency of a statistical threshold value (STV) of 410 counts/100 ml, both in an assessment period of up to 90 days.

In transition and saltwater, Enterococci bacteria shall not exceed a geometric mean of 35 counts/100ml and shall not have greater than a 10% excursion frequency of a statistical threshold value (STV) of 130 counts/100ml, both in an assessment period of up to 90 days.

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

2. In VPDES discharges to freshwater, bacteria in effluent requiring disinfection shall not exceed a monthly geometric mean of E. coli bacteria of 126 counts/100ml. Alternative performance standards may be established where an approved long term control plan establishes an alternative level of disinfection for a combined sewer system.

In VPDES discharges to transition and saltwater, bacteria in effluent requiring disinfection shall not exceed a monthly geometric mean of enterococci bacteria of 35 counts/100ml.

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)

Statutory Authority

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

Historical Notes

Derived from VR680-21-02.2, eff. May 20, 1992; amended, Virginia Register Volume 14, Issue 4, eff. December 10, 1997; Volume 19, Issue 7, eff. January 15, 2003; Volume 20, Issue 9, eff. February 12, 2004; Volume 26, Issue 12, eff. February 1, 2010; amended Virginia Register Volume 36, Issue 6, eff. October 21, 2019.

Website addresses provided in the Virginia Administrative Code to documents incorporated by reference are for the reader's convenience only, may not necessarily be active or current, and should not be relied upon. To ensure the information incorporated by reference is accurate, the reader is encouraged to use the source document described in the regulation.

As a service to the public, the Virginia Administrative Code is provided online by the Virginia General Assembly. We are unable to answer legal questions or respond to requests for legal advice, including application of law to specific fact. To understand and protect your legal rights, you should consult an attorney.