By John Schaffner
johnschaffner@reporternewspapers.net

The Upper Chattahoochee Riverkeeper organization continues to find higher-than-desired levels of contamination in Tanyard Creek as it flows through Buckhead’s Tanyard Creek Park.

The Riverkeeper is working with the city of Atlanta to find the source of contamination upstream from the park. The cooperative project between the Riverkeeper and the city’s Department of Watershed Management started June 9.

“We have also done several source-tracking events where we have walked up the creek and taken samples from every outfall into the creek,” the Riverkeeper organization’s Technical Program Director Jason Ulseth wrote in an e-mail to the Collier Hills Neighborhood Association. Members of the association take water samples in the park every Thursday.

Ulseth and DWM inspectors have walked from Tanyard Creek Park to the Combined Sewer Overflow (CSO) unit’s gates at I-75, pulling water samples out of the stream and sources flowing into it.

In late May, Ulseth said he had analyzed his samples for E. coli bacteria. A sample taken at one source flowing into the stream registered 11,000 MPN/100 milliliters. Another sample registered 7,000 MPN/100 milliliters. That was before they became diluted by the stream water. MPN stands for “most probable number” and is a standard measurement of bacteria.

In his recent e-mail, Ulseth said continued samplings upstream from the park “have shown two particular outfalls with reasonably high levels. We will need to do additional sampling in these areas during dry and wet periods to properly document the outfalls. Then we can use that data to go to the city and map out the sub-watersheds and find the source.”

Ulseth reported that “in the meantime, the continuous data from samples” taken in Tanyard Creek Park by Collier Hills resident volunteers “are proving extremely helpful.”

The highest recent reading from the Tanyard Creek Park samplings was 18,270 MPN/100 milliliters. That was 77.7 times the 235 MPN/100 milliliters the Environmental Protection Agency considers standard for recreational water quality.

Every sample taken since May 20 has exceeded the 235/100 milliliters standard. The lowest level of contamination was 420/100 milliliters, recorded on July 15.

The data are available on EPD’s Adopt-A-Stream website: http://georgiaadoptastream.com/db/Sites.asp. Type Tanyard Creek in the box and it will pull up the results.