(BLOOMINGTON) – Treated wastewater discharged into Clear Creek in July from the Dillman Road Wastewater Treatment Plant exceeded the daily limit of 235 colony-forming units (CFUs) of E. Coli bacteria per 100 ml four times in 30 days; the limit is three times in a 30-day period. This event was reported to the Indiana Department of Environmental Management (IDEM).
Between April 1 and October 31, the Dillman plant utilizes chlorine to disinfect treated wastewater, then dechlorinates the water before releasing it into Clear Creek. This process removes E. coli from plant effluent to levels consistent with the National Pollutant Discharge Elimination System (NPDES) permit before it enters the stream. After routine testing showed higher than normal results, CBU identified a malfunction of the automated chlorine feed and immediately corrected it. A visual inspection of the creek flowing from the plant showed no indications of degraded water quality or evidence of adverse impacts to plants or wildlife.
Utilities staff monitor E. Coli levels in the treated water that flows into the creek on a daily basis. There have been no previous violations this year, and there were no violations last year. Staff are reviewing all maintenance and operating procedures, and conducting staff training to prevent a recurrence.
“CBU is vigilant in maintaining and generally surpassing the most rigorous water and wastewater quality standards,” said Utilities Director Vic Kelson. “This small aberration is the first in the last two years, and we detected and addressed it promptly. Although the level of potential impact is minimal, CBU is committed to sharing information with the community about the safety of both our wastewater and our drinking water.”