LAKE COUNTY, Calif. – Lake County’s Public Health officer offered additional information this week about testing results reported on Friday that showed the presence of the virus that causes COVID-19 in local sewage.
Last week, Lake County Special Districts received testing results showing that SARS-CoV-2, the novel coronavirus that causes COVID-19, was found in raw sewage at all four of its sewage treatment plants, as Lake County News has reported.
Biobot, a Massachusetts-based company, is conducting the testing as part of its pro bono COVID-19 response program, which is being carried out nationwide in collaboration with researchers at MIT, Harvard and Brigham and Women's Hospital.
The weekly tests began on March 26 and continued on April 1, with no virus detection. Then, samples taken on April 8 showed the presence of the virus in Special Districts’ four sewage treatment plants: Kelseyville, Middletown, Northwest Regional in north Lakeport and Southeast Regional in Clearlake, the agency reported.
The South Lakeport wastewater collection system moves effluent to the city of Lakeport’s wastewater treatment facility through a formal agreement between the two agencies. It wasn’t included in the Biobot testing to date.
Testing of sewage at the city of Lakeport’s wastewater treatment facility isn’t currently taking place, according to city Utilities Superintendent Paul Harris.
“We do intend on sampling our raw sewage for COVID-19,” Harris said. “The problem is the lab that performs these tests is currently at capacity and cannot do any additional sampling at this time. They are working on expanding their capacity and we are on a waiting list.”
In the meantime, Lakeport Public Works Director Doug Grider said they have installed the testing ports in order to be able to collect the samples once they can get a slot with the testing company.
Biobot is among a number of companies, universities and researchers studying how to monitor the presence of SARS-CoV-2 in communities by tracking its presence in sewage, as the virus is shed in the stool of those who are infected with it.
Lake County Public Health Officer Dr. Gary Pace said in a Monday statement that in a followup call with Biobot, county officials learned the company has researched fecal stools of COVID-19 patients at a Boston hospital and found the virus does not shed consistently in all patients.
Some patients shed more one day, less the next and more the third day. Pace said some patients also shed the virus in stools for a few days, while others shed it up to two weeks.
“Because of these variables, it is not possible to know the number of cases in the county by detections,” Pace said. “This tool is most useful as an indicator of whether cases are increasing or decreasing. By continuing the testing, it will also become a valuable tool to gauge COVID-19 activity when we open the economy back up.”
Pace said all four sewage treatment plants had estimated cases at less than 1 percent of catchment so the numbers are relatively small.
The date of the April 8 test, he added, “does coincide with the six confirmed cases in the county.”
In response to concerns from members of the public about sewage, Pace said raw sewage has many contaminants that are hazardous.
“This is why our staff must always take precautions and sewer spills are always considered an extreme emergency. Although staff will continue to treat all raw sewage as hazardous, it is believed the virus is killed by the amount of detergent and bleach present in raw sewage,” he said.
He said some have also expressed concern about water supplies. “Sewer and water are not related, and what is in the raw sewage at the treatment plant has nothing to do with any public water system. Also, it has been proven this virus will not survive the treatment process of public water systems.”
Pace said other concerns have focused on the lake. “Public sewer systems do not discharge into the lake, so these findings do not affect Clear Lake,” he said.
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Health officer discusses raw sewage testing that revealed presence of COVID-19 virus
- Elizabeth Larson
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