Almost anywhere rain falls, from the Baltimore Beltway near Towson into southern Pennsylvania, that water will probably end up in the Loch Raven Reservoir.
Likewise, if a cigarette hits the ground, or motor oil is spilled, it'll join the runoff water bound for the reservoir.
Watershed rangers, who patrol the reservoir for the Baltimore City Department of Public Works, can no more stop pollution than they can make it rain, but they do their best to protect the reservoirs themselves and the forest buffers surrounding them.
Officials say the summer season — when young people are out of school, families are looking for day trips and the reservoir beckons a respite near home — is a particularly challenging time.
Loch Raven Reservoir, like Liberty and Prettyboy reservoirs, is owned by the city and maintained by the city's Department of Public Works. The reservoirs provide water for people in Baltimore and Baltimore County, as well as parts of Anne Arundel and Harford counties.
The property around Loch Raven Reservoir is irresistible to fisherman, nature lovers, bikers and families looking to enjoy the outdoors; and for people seeking nearby refuge from the traffic, chaos, noise and pace of metropolitan life.
Still, the reservoir is not a park. It's a water supply for 1.8 million people.
"The dirtier the water is, the more it costs the customer to make that water clean," said Celeste Amato, a spokeswoman for the city's Department of Public Works. "We do allow some recreation, but we're very restrictive."
The reservoir can't function like a park because the Department of Public Works is required by law to protect the drinking water, and overuse leads to erosion and damages plant life, Amato said.
"All the trees and plants on that property make the water cleaner," she said.
Enter the watershed rangers.
"We call them rangers, but they are police officers," Amato said. "They have real handcuffs — and they'll take you to a real jail if they have to."
'I'm not a park ranger'
Currently the city employs seven rangers, shared among its reservoirs, and hopes to hire about five more.
One of them is Ranger Janos, who declined to provide a first name. Janos used to be a Baltimore City police officer.
Janos wears a Kevlar vest and a utility belt with a Taser, pepper spray and a 9mm handgun. He unholstered the gun to show a visitor the magazine, fully loaded with 16 rounds.
"I'm not a park ranger," Janos said. "I'm not handing out maps and waving to people."
On his small police boat, Janos constantly scans the water and shoreline. He says the job is, "99 percent environmental: to protect the water supply."
His binoculars are almost always at his eyes, looking at a boat or at fishermen to see that no one's drinking alcohol, smoking marijuana or littering.
On a day last week, after leaving the dock at the reservoir dam, Janos slowed the boat near Loch Raven Reservoir's famous cliff, which is off limits to the public.