It’s safe to swim at Kenneydell Beach again. But what caused the contamination?
Thurston County lifted a swimming advisory at Kenneydell Beach on Saturday, but the cause of the contamination found last week is still unknown.
Water quality tests from Thursday and Friday indicated the levels of fecal coliform bacteria at the beach had dramatically dropped to acceptable levels, said Art Starry, director of the county’s Environmental Health Division, during Tuesday’s Board of County Commissioners meeting.
“We are going to continue to investigate to see if this is just an anomaly or if there’s something more to it,” Starry said. “At this stage, we believe the water quality has improved over the course of a couple of days and several samples, and so we were satisfied that it was appropriate to lift the warning.”
On Thursday, the county advised residents to avoid swimming at the Black Lake beach after finding heighten levels of bacteria in water quality tests from June 22. High amounts of fecal coliform bacteria, which live in the digestive tract of warm-blooded animals, can indicate sewage or feces contamination, according to a county news release.
The water quality tests from Tuesday indicated the water had average fecal coliform concentrations that exceeded the acceptable limit of 200 organisms per 100/ml for a set of samples taken on a single day.
One sample from the beach even measured over 1,000 organisms per 100/ml, the release says.
Starry said the tests conducted on Thursday and Friday indicated a dramatic improvement in fecal coliform levels.
“The good news was that the samples that we took on Thursday showed a dramatic improvement as far as water quality is concerned, dropping from the neighborhood of 1,000 organisms per 100/ml, or about 4 ounces of water, to sometime below detection limits,” Starry said. “The highest sample was around 35 (organisms per 100/ml).”
Although the water quality improved, Starry said the cause of the contamination is still unknown. He said his staff found no unusual activity at nearby properties or a small tributary that drains into the lake.
“Our staff are really well trained to be discerning about where they sample so as to not pick up a clump of debris or anything that looks as though it would be a contaminant,” Starry said. “So, it was surprising to have those high levels, especially at multiple sampling sites.”
Starry said it’s county policy to maintain the advisory until the cause of the contamination is found and addressed. If the cause cannot be found, county policy allows them to lift the advisory if two sets of samples indicate the water is safe.
Thurston County Public Health and Social Services director Schelli Slaughter assured the board that water quality at the beach is routinely monitored.
“We do routinely sample at Kenneydell during the summer months and it is currently safe for use,” Slaughter said.
Commissioner Gary Edwards asked Starry if a large flock of geese may have contaminated the water just before his staff tested the water.
“I suppose it’s a possibility, but when I was there — I did sample on Friday — it was a very nice clean park,” Starry said. “It’s well maintained. There wasn’t evidence of a lot of bird activity.”
Commissioner Tye Menser asked Starry if the contamination found last week is unusual for Black Lake overall, but Starry said the county does not routinely test the other areas of the lake.
“Our one sampling area is Kenneydell Park because that’s a county facility and we want to be cautious there,” Starry said. “I can’t tell you for sure what water quality is around the rest of the lake. When we’ve done other sampling for different purposes … we haven’t seen high numbers.”
This story was originally published June 30, 2021 at 10:41 AM.
