2016 Bacteria Testing—Virginia Data

Woman uses a collection bottle on a pole to collect water samples in stream.

CBF volunteer Meredeth Dash collects water samples for the summer 2016 bacteria study at the Beaverdam Creek testing site.

Kenny Fletcher/CBF Staff

In Virginia we kicked off a pilot bacteria monitoring program this year, sampling four spots in the greater Richmond area that represent the variety of waterways in the region. The sites included a popular swimming and paddling spot on a forested stretch of the James River, leafy suburban streams, and the mouth of a heavily urbanized creek near downtown Richmond.

A dedicated team of volunteers and CBF staff sampled throughout the summer, largely within 24 hours of rainfalls of one half inch or more. Testing for E. coli was completed by a certified commercial lab in Richmond.

High Bacteria Levels at Three Sites

At three of the four sites, numerous samples came in with bacteria counts well above Virginia's recommend limit for swimming or recreational contact (235 colony forming units of E. coli per 100 milliliters). Some of those samples found extremely high bacteria counts in the thousands. We plan to share our results with the Virginia Department of Environmental Quality (DEQ), contributing to the Commonwealth's efforts to track the health of our waters. Virginia's DEQ considers all four sites we sampled impaired for recreational use due to high E. coli levels.

The highest bacteria levels were found in samples taken where Gillies Creek enters the James River in Richmond. That spot is plagued by combined sewer overflows, which during heavy rains release sewage and polluted runoff into the creek. One reading there topped out at more than 100 times Virginia's limit for recreational use. Richmond is making progress with its combined sewer control program, and is currently focusing on improvements at Gillies Creek.

The Connection Between Rain and Bacteria

At three of the four sites, the majority of post-rainfall samples came in over Virginia's limit for recreational contact. This pilot project illustrates that polluted runoff could be contributing to the bacteria problem in some of the waterways we sampled.

In Virginia, support for the Stormwater Local Assistance Fund is crucial in the fight against runoff. The Fund provides matching grants to cities, towns, and counties to put in place effective and efficient projects that stop the flow of pollution into our waterways.

CBF's pilot Virginia bacteria monitoring program is one of several efforts in Central Virginia that help paint a picture of the health of our waterways. Other organizations undertaking water quality monitoring in and around Richmond include:

The map and chart below includes data for E. coli levels from sites in Richmond City, Chesterfield, and Hanover Counties in Virginia. Learn more about this project or select a site on the map below to view the results.


E. coli (cfu/100ml) Geometric Mean - Wet Weather: 0 to 126 126 to 235 235 to 2,419 2,419 to 5,497



Red values = E. coli counts greater than Virginia's standard of 235 cfu/100 mL. Swimming or other contact could pose a health risk at the time of sampling due to high bacteria levels.
Red values (underlined and italicized) = E. coli counts greater than the maximum detection limit for analysis performed that day.
Light blue background = .5 inches or more of rainfall at least 24 hours before collecting water samples


E. coli bacteria are found in the digestive system of warm-blooded animals, including all birds and mammals. Their presence in surface water indicates recent contamination with fecal waste. Counts are expressed as cfu or colony-forming units. Virginia standards suggest swimming or recreational contact should be avoided when counts are greater than 235 cfu/100 ml. Water samples were taken within 24 hours of a rainstorm of .5 inches or more. All samples tested at Microbac Laboratories in Richmond, a commercial lab certified by the Virginia Environmental Laboratory Accreditation Program for potable and non-potable water sampling and analysis. 

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