ASHLAND — An advisory against water contact at a popular Ashland Creek swimming hole will remain in place after tests Wednesday showed unhealthy levels of E. coli bacteria — but the contamination was apparently not associated with Tuesday's spill from an upstream sewer line, authorities said.
Test results from where 500 gallons of water used to cleanse filters at the city's water treatment plant spilled into the creek showed extremely low levels of E. coli, according to city and state officials.
But tests of the swimming hole showed red-hot levels of E. coli that exceed state Department of Environmental Quality standards for a single sample, said Greg Whittenburg, chief operator of the city's wastewater treatment plant.
"The swimming hole amounts were astronomical," Whittenburg said.
More tests are planned today, and the voluntary advisory against swimming or wading there will remain in effect, Whittenburg said.
DEQ engineer Jon Gasik said the low test results at the spill site show that that water does not appear to have been the source of the E. coli.
No source, however, has been detected, Whittenburg said.
E. coli, a form of fecal coliform bacteria, is closely associated with human and animal waste. People who ingest E. coli-infected water can develop abdominal cramping, diarrhea and nausea. It is most dangerous to younger and older people, as well as those with poor immune systems.
E. coli levels in Ashland Creek and several creeks in the upper Rogue River Basin commonly test above unhealthy levels during low-flow summer periods. Streams such as Griffin Creek and Jackson Creek in Central Point currently sport similar E. coli-related advisories against water contact.
Water samples in Ashland Creek were taken Tuesday after water treatment plant workers noticed that a pipe delivering so-called "backwash" — water used to clean sediment from filters — clogged, spewing the water out of a manhole cover and into the creek.
Sediment is flushed from filters in the later stages of treating water before it is piped to city users. The backwash water is then piped directly to the wastewater treatment plant.
The water that leaked into the creek normally contains sediments and was not expected to have E. coli in it, but the DEQ ordered the tests just to be sure.
Reach reporter Mark Freeman at 541-776-4470 or firstname.lastname@example.org.