Warning signs posted on bright orange markers in Glencarlyn Park caution visitors such as Hussein Rojas to avoid drinking from the stream and to keep pets away from the water.
"My dog usually loves the water, and he just drinks and drinks," Rojas said.
Sewage that spilled out of a manhole at the park over the weekend may still be contaminating the water flowing downstream from the area.
Officials said the contaminated area of the Upper Long Branch stream begins near the Long Branch Nature Center and continues through Four Mile Run, down to the Potomac.
Bob Mace, the Water, Sewer, Streets bureau chief for Arlington County, said the county would issue the safety advisory through next weekend.
The county may need to re-line the pipe that caused the sewage leak, Mace said.
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