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USGS Georgia Water Science Center: Chattahoochee River BacteriAlert


Chattahoochee River BacteriAlert Program

Current National Park Service Chattahoochee River Bacteria Health Advisories

Chattahoochee River at Norcross (Medlock Br. Rd)
Currently, there is not a National Park Service health advisory in effect
Chattahoochee River at Atlanta (Paces Ferry Rd)
Currently, there is not a National Park Service health advisory in effect

Current turbidity and estimated E. coli bacteria counts for the Chattahoochee River

Most recent turbidityEstimated E. coli count
SiteDate/TimeTurbidity, in NTU
Chattahoochee River at Norcross (Medlock Br. Rd) 09/05
7:15 AM EST
4 50
Chattahoochee River at Atlanta (Paces Ferry Rd) 09/05
7:45 AM EST
9 99

Chattahoochee River at Norcross: The last E.coli water sample was taken on Thursday 08/27 at 10:55 AM; the measured E. coli count was 330
Chattahoochee River at Atlanta: The last E.coli water sample was taken on Thursday 08/27 at 9:30 AM; the measured E. coli count was 132

Background:   How safe is it to swim, wade, and boat in the Chattahoochee River today? For a highly urbanized river such as the Chattahoochee, much of the answer depends on bacteria levels in the water. This website provides "real time" turbidity data, the estimated E coli bacteria count, the most recent E. coli bacteria counts (sample collected each Thursday), and National Park Service health advisories for two locations on the Chattahoochee River (view map).

Current conditions

Here are the current conditions for the Chattahoochee River sites:

Estimating E coli

E. coli predictions are based on the current turbidity values. It is important to understand how the bacteria counts are estimated using turbidity. After taking many water samples, the sampled turbidity and actual E coli counts were analyzed statistically, which showed that as turbidity went up so did E coli counts. The statistical "best fit" formula (shown below) was produced, which is used to estimate E coli counts. But, it is important to realize that the actual (sampled) E coli counts vary a great deal even at the same turbidity. Thus, the water samples taken when turbidity was at, for example, 50 could produce E coli counts of 500, 1000, or 1,500. As all of these results are from actual samples, and each E coli count is accurate.

This just means that there is a lot of variability in the data. In this Website, the estimated E coli count is produced using the average of the samples taken at any specific turbidity. To try to summarize simply, when we show the estimated E coli count, the actual E coli at that moment might be much more or much less than the estimated count, but, using past data, the estimated value is the average of the range of sampled values, for that turbidity. And, most important, E coli counts do go up as turbidity goes up, and the National park Service advisory statements should be considered valid.

Understanding the data
Find out about the bacteria
E.coli data tables (last 20 weeks)

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The Chattahoochee River BacteriALERT project is a partnership between the National Park Service, the Chattahoochee Riverkeeper, and the Cobb County Water System, and agencies and organizations playing a direct role in the Chattahoochee BacteriALERT ar
List of  agencies and organizations playing a direct role in the Chattahoochee Riverway BacteriALERT

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