Low levels of a microscopic parasite called cryptosporidium were detected in water tested from Druid Lake Reservoir, Baltimore City officials announced Thursday morning.
Parts of Baltimore City, Baltimore County, and Howard County are impacted by the portion of the Baltimore region’s water system affected by the parasite.
Cryptosporidium levels were at about 0.09% in the most recent results, “a very low percentage,” said Richard Luna, interim director of Baltimore City’s Department of Public Works.
That also means it presents a low risk to the health of the general public, said Dr. Tamara Green, the Baltimore City Health Department’s chief medical officer.
“For most people, if they have a healthy immune system, they will not have any symptoms,” Green said. “But we want people to be vigilant and to monitor their symptoms.”
However, children, the elderly, and immunocompromised individuals (such as those with HIV, AIDS, cancer, or other illnesses affecting the immune system) are at a greater risk of illness from the parasite.
Symptoms of illness related to the parasite can include diarrhea, gastrointestinal upset, vomiting, and fever.
“Any incidence of high fever or severe pain, we ask that you contact your primary care provider or reach out to seek advice,” Green said.
City Administrator Faith Leach stressed “This is not E. Coli,” referring to the incident over Labor Day weekend, when the city detected E. coli in water collected in West Baltimore.
“I don’t want to conflate E. coli with cryptosporidium; these are two completely different things,” Leach said. “Again, I think the big takeaway from this call is that we believe that our drinking water remains safe for the general population.”
She added that “out of an abundance of caution,” the city has put out recommendations for immunocompromised individuals and other sensitive populations.
The city has not issued a boil water advisory for the general population in the affected areas, but they do advise individuals with compromised immune systems and other sensitive populations to drink bottled water; boil water for one minute before consuming it; or use filtered water.
For those individuals, tap water should be filtered using a filter labeled ANSI/NSF 53 or 58 standards, or a filter designed to remove objects 1 micron or larger, including those labeled “absolute 1 micron.” Brita filters and other similar items should not be used.
Green also encouraged residents to wash their hands regularly, especially when interacting with someone who is showing symptoms, including diarrhea and vomiting, or when handling dirty diapers.
Impacted areas include: central, northeastern, and southwestern parts of Baltimore City; central, eastern and southern parts of Baltimore County; and a smaller portion of eastern Howard County. See the map below for specific boundaries.
The parasites were detected during routine monthly sampling conducted earlier this month.
City workers collected water samples from the Ashburton and Druid Lake reservoirs on Sept. 19, and sent those samples to a laboratory for testing. They were returned on Tuesday, Sept. 26, with the Druid Lake samples showing a positive result for cryptosporidium.
Baltimore City on Tuesday notified the Environmental Protection Agency and the Maryland Department of the Environment of the positive results, and on Wednesday coordinated with the EPA and other partners on next steps. Howard and Baltimore counties were also alerted on Wednesday.
The city collected another sample Wednesday, which was again sent to a laboratory. Test results are typically returned in 5-7 days, Luna said.
The water that was in the reservoir Sept. 19, when this month’s initial samples were collected, has already been distributed into the portion of the Baltimore region’s water system that serves the affected areas.
The Sept. 19 sampling was the second monthly testing that Baltimore City has conducted as part of a new requirement from the Environmental Protection Agency. The first tests were conducted in late July and early August. Those first samples, taken both at Ashburton and Druid Lake, indicated no positive results.
Baltimore City and its partners have not determined how the water became contaminated with cryptosporidium.
“The sample that was collected and the results back were so low that it was even hard for the laboratory analysts to detect that bacteria, the crypto, in that sample,” Luna said. “Per their guidance, they said it would be too difficult to pinpoint the exact source.”
Cryptosporidium, as well as another parasite called giardia, are typically found in raw water.
Raw water reservoirs, like Liberty, Prettyboy, and Loch Raven, are tested and treated before their water enters the Baltimore treatment system and distribution center.
Druid Lake is an open air reservoir, where treated water has already gone through the city’s filtration process and then goes out into the distribution system.
“We’re currently working as part of the EPA order to get that lake, as well as Ashburton, into a covered tank that would be completely protected from the elements,” Luna said.
Luna said those projects are currently on schedule, with the Ashburton covered tank planned for completion by Nov. 30, and the one at Druid Lake to be completed by Dec. 30.
Bryan Doherty, director of communications for the Mayor’s Office, said information will be released to the public via the Department of Public Works and the mayor’s channels.
