Swimming and Water Testing

Purcell City Lake Swimming Area: Water Testing Frequently Asked Questions (FAQs)

Oklahoma Department of Environmental Quality (DEQ) Swimming in Oklahoma’s Lakes, Rivers, and Streams PDF
Follow this link to read: DEQ Offers Tips to Keep You Safe at Lakes, Rivers, and Streams

Why does the City of Purcell test for E. coli in City Lake?
Lake water is tested to determine if the amount of bacteria reaches a level that the Environmental Protection Agency advises a posting of quality.

Notice Sign Will Be Placed In Swimming Beach Area if Test Results Exceed 320 CFU of E. coli.
The Environmental Protection Agency (EPA) research recommended a value of 410 colony forming units (CFU) of E. coli per 100 mL as the threshold for an advisory for recreation waters use. The City of Purcell has chosen to use the more conservative value of 320 CFU that was offered in the research for a lower threshold. The extensive research conducted by the EPA can be found in the document https://www.epa.gov/sites/production/files/2015-10/documents/rwqc2012.pdf  

The National Park Service at the Chickasaw Recreation Area states on their website "Bacteria levels may fluctuate from day to day. When collected samples exceed E. coli limits, the public health standard requires the previous four weeks be averaged with the current readings to monitor long term trends. If the five week average and/or geometric mean is above the action level, the beach is posted with a sign notifying the public of high bacterial levels in the swimming area. When both the five week average and geometric mean fall below the action level, the notices signs are removed.”  The City of Purcell follows that measurement and posting protocol, using the EPA recommendation of 320 E. coli CFU threshold.

Other visitors are swimming even though a notice sign is posted. Is it safe?
The City of Purcell will post test records on this page and when above 320 E. coli CFU on the beach to inform the public.  This policy allows visitors to make their own decisions about recreation in the Lake.  As always, consider your level of health before a choice of activity in the Lake.

Blue-green Algae presence: The Oklahoma Department of Health recommends avoiding swimming if seen in the area. https://www.ok.gov/health/Prevention_and_Preparedness/Acute_Disease_Service/Disease_Information/Blue-Green_Algae.html

Follow this link to view TravelOK's Lake Conditions website.