By John Schaffner
The Upper Chattahoochee Riverkeeper organization plans to expand its testing of E.coli levels along Tanyard Creek after a sampling from the urban stream in Tanyard Creek Park March 11 registered more than 220 times the standard level.
The U.S. Environmental Protection Agency says water used for recreation should not contain more than 235 cfu/100 millileters, according to Riverkeeper watershed protection specialist Jason Ulseth. During the March 11 measurement, Tanyard Creek water was found to contain 52,310 mpn/100 milliliters, Ulseth said.
The Riverkeeper uses the mpn (most probable number) measurement, which is virtually the same as the cfu (colony forming units) measurement, Ulseth said.
Ulseth said he met with officials of Atlanta’s Department of Watershed Management on March 22 to try to determine the cause of the high readings after another sampling registered a high reading during a relatively dry period.
On March 18, a test recorded more than 2,000 cfu/100milleters. Ulseth said other recent readings at the Tanyard Creek Park sampling area have ranged from 200 to 300 cfu/100 millileters during dry periods.
The March 11 sampling, according to Ulseth, was taken “after a couple of days of moderate to heavy rain.” He said they had never before gotten a reading as high as the March 11 reading of 52,300.
Ulseth said that when he met with the city Watershed Management officials “we got out a map and determined some other spots upstream from Tanyard Creek Park for taking additional samplings in the future.”
He said they likely will add two or three new sampling locations, but they do not have the funds to sample in those areas on a weekly basis, as is being done in Tanyard Creek Park.
Collier Hills neighborhood volunteers sample the water from the creek at the same location in Tanyard Creek Park every Thursday around 1 p.m. and deliver the samples to the Riverkeeper’s offices in Puritan Mill on Joseph Lowery Boulevard.
The initial concern was that there may have been an overflow at the Tanyard Creek Combined Sewer Overflow (CSO) station, which is upstream of Tanyard Creek Park and off Deering Road in the Loring Heights neighborhood.
Ulseth said that DWM reported that there was not an overflow that would have been associated with the recent high E.coli readings.
After the meeting with city water officials, Ulseth said new sampling locations will be added to determine if the contamination may be coming from places upstream where large numbers of geese congregate, from two major tributaries that flow into Tanyard Creek on the other side of I-75 or from several apartment complexes along the creek on both sides of I-75.