An Aberdeen Proving Ground wastewater treatment plant overflowed Tuesday and sent about 250,000 gallons of partly treated sewage into the Bush River, the Army reported Thursday.
"The bypass was caused by extreme rainfall totaling 3.66 inches in 24 hours," spokesman Kelly Luster said in a press release.
The sewage bypassed the second clarifier tanks into the chlorine contact chamber, according to the press release. The treatment plant is in the Edgewood area of the post.
The spill happened between 4:30 and 7:30 p.m., Harford County Health Department spokesman Bill Wiseman said.
Signs were posted reading, "No Fishing, No Crabbing, No shellfish harvesting, No Swimming, in the area until further notice."
Luster said such an overflow last happened this winter, when two inches of rain in a short time caused 3,000 gallons of sewage to spill.
"While every precaution is taken to avoid such occurrences, this bypass occurred due to an extraordinary amount of rainfall," he said, noting 3.66 inches were measured within six hours.
"Regardless of what measures are in place, the extreme amount of rainfall is an uncommon and uncontrollable event," he said.
Luster said the health of the community and environment are top priorities and noted that any wastewater that was released was partially treated and chlorinated.
"Samples taken from the affected area are being sent for analysis," he said.
Army experts continue to monitor the area and the Harford County Health Department and Maryland Department of the Environment were notified, according to the release.
The Health Department does not have jurisdiction over the federal property, Wiseman said.
Maryland Department of Environment spokeswoman Adrienne Diaczok said via e-mail that the main environmental and public health threat from an overflow is bacteria in waterways.
"Wastewater treatment facilities must report overflows within 24 hours and submit more detailed reports within five days," she also said.
She said it is too soon to say what impact this specific spill may have.