GLEN COVE, N.Y. (CBSNewYork) — Long Island officials are crediting a Glen Cove resident with diagnosing a serious pollution problem.

The man was able to pinpoint the source of leaking sewage that was threatening part of Long Island Sound.

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“From my childhood years, I knew that the water is always clean, it didn’t smell,” Glen Cove resident Joe Douso told CBS2’s Carolyn Gusoff.

Douso knows his native Glen Cove. He grew up there, exploring the ponds and creeks and an underground drainage tunnel that carries rain water from the center of the city to Long Island Sound. And he knows when something doesn’t smell right.

“The water was a whitish color. It had a very bad odor, just like sewage,” Douso said.

The smell was especially concerning because all summer bacterial levels leading to the Sound were alarmingly high. Monitoring by environmental groups for three decades was suddenly spiking.

“The levels were really high, and it was very concerning. I mean, we have a lot of fishermen here,” Glen Cove Harbor Patrol Chief John Testa said.

Monitoring teams with Coalition to Save Hempstead Harbor saw their weekly bacteria results as much as 60 times higher.

“This just would degrade the water quality of Hempstead Harbor that we’ve been working so hard to clean up,” said Carol DiPaolo with Coalition to Save Hempstead Harbor.

So Douso decided to go exploring again, this time as good Samaritan on a mission to find the source of the pollution.

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“So I walked where the entrance is with my boots and iPhone and flashlight,” Douso said, “and found a large sewer pipe that was broken dumping sewage right into this drainage tunnel. Raw sewage right into the stream.”

Hidden beneath Glen Cove’s roads was a break in a sewer line, spewing raw sewage into the waterways.

City officials alerted Nassau County, which immediately bypassed the broken pipe, bringing bacteria levels back down.

“If the break had not been found, this could have gone on for years and years, contributing more and more bacteria to the creek, which leads into the harbor, right where there’s beaches, shellfish beds and could jeopardize them for the long term,” said Eric Swenson, with the Hempstead Harbor Protection Committee. “He’s a hero to find it, but it really was teamwork.”

Officials credit a citizen detective and teamwork.

“Great save,” DiPaolo said. “This is the way it’s supposed to work.”

Proving that water monitoring works.

“Sometimes it’s small, like I did, but it comes out with big results,” Douso said.

And so does caring about your hometown.

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The waste waster treatment plant in Glen Cove has set up a bypass while they make permanent repairs to the broken sewage pipe.

Carolyn Gusoff