Someone pried a 100-pound manhole cover off a sewer line in South Carroll, broke it into pieces, then jammed it and other debris into the line, causing about 2 million gallons of raw sewage to overflow into a nearby tributary of Piney Run.
Carroll County health officials spent much of yesterday afternoon posting 200 signs two miles along the stream to the Patapsco River, advising swimmers and anglers to stay out of the water.
"To have the loss or the degradation of these very rare, pristine and naturally clean streams is just a terrible thing," said Richard McIntire, spokesman for the Maryland Department of the Environment.
Before the incident, the stream had been classified by the state as having among the highest water quality in Maryland. Yesterday, 200 yards downstream from the spill, environmental experts encountered chunks of gray matter, clumps of toilet paper and a lack of fish.
Drinking water was not affected. Carroll's Bureau of Utilities is offering a $1,000 reward for the arrest and conviction of the vandals.
Raw sewage poses a health threat to humans because it contains viruses and other pathogens carried by human waste, said Edwin F. Singer, Carroll's assistant director of environmental health. He expects his office will lift the health advisory within a few weeks. Carroll officials believe the spill occurred between May 7 and Monday.
The extent of the damage to the environment caused by the spill, near Sykesville, won't be determined for weeks. Environmental officials can't clean up the sewage. They are waiting for the stream to flush out the wastewater on its own and will continue testing the water to determine when aquatic life has returned to normal.
"It's not like we can take some magic sponge and soak this stuff up," McIntire said. "Mother Nature takes a while to correct herself."
The crime, which county officials termed an act of "malicious, premeditated destruction," was detected Monday afternoon in the county's right of way through Springfield Hospital Center property off Slacks Road.
The Piney Run pumping station, which serves 7,200 customers in the Freedom area, generally pumps between 1 million and 1.4 million gallons of wastewater a day to the treatment plant 1.5 miles away. On Monday, however, a Carroll mechanic noticed the volume of water being pumped was lower than usual.
After discovering the treatment plant was also operating at a lower volume than usual, the mechanic returned to the pumping station and discovered the overflow. Workers spread lime on the ground affected by sewage to reduce the possibility of bacterial contamination. They worked for hours to remove pieces of metal, bricks, rocks and mortar blocking the line and to restore the collection system, according to Gary Horst, director of Carroll enterprise and recreation services who estimated damage to the utilities site at $5,000 to $10,000.
"It's a terribly thoughtless thing to have done," Horst said. He urged anyone with tips or questions about the spill to call the Bureau of Utilities at 410-386-2164.
The spill was reported yesterday morning to the Maryland Department of the Environment.
South Carroll customers did not experience backups in their plumbing as a result of the vandalism because the sewer line was 20 percent to 30 percent blocked, Horst said.
Vandals, if convicted, could be charged with malicious destruction of property, which carries a maximum penalty of three years in prison and a fine of $2,500, according to the Carroll state's attorney's office.
Sewage overflows caused by vandalism occur a few times a year, McIntyre said. Twice in one week in March, vandals in Anne Arundel County clogged sewer lines, sending more than 20,000 gallons of wastewater into tributaries of the Little Magothy River and Forked Creek.