Sewage-treatment workers earn an average of about $42,000 a year, a figure unchanged since 2001. Los Angeles pays a starting salary of $71,000 for similar work.

The other union, Local 3 of the International Brotherhood of Electrical Workers, declined to discuss the status of its effort. It represents two categories of workers at the plants, including the plant managers, who have not seen a cost-of-living raise since 1995 and make an average of $59,600 a year — less than many of the people they supervise.

“That’s a travesty,” said Frank Esposito, a plant manager who retired this month after 36 years with the Department of Environmental Protection. “But in the last 10 years, we turned around the Hudson River and the East River. And you never heard about us causing a job action. That’s what I’m proud of. We did our jobs.”

The job today is a mix of old-world toil and a modern technician’s skills.

Raw sewage flows into the 14 treatment plants scattered around the city’s waterfront. Solid matter settles in holding tanks and is sold as fertilizer. The remaining water undergoes treatment before being released into the surrounding waterways.

The workers take federally required water and solid-matter samples at specific intervals. They monitor levels of dangerous gases, including methane and hydrogen sulfide, and handle chemical and biological agents.

That predictable routine goes on every day. But the workers are also the jack-of-all-trades repairmen when something goes wrong. They perform emergency repairs on climate control systems, chlorination devices and huge pumps. Most come from construction backgrounds; they must have skills in plumbing, welding, masonry and carpentry. They take holding tanks off line and wade in to perform repairs.

“I’ve been knee deep in raw sewage at 7:15 in the morning, and let me tell you, it don’t smell like Folgers in your cup,” said Anthony Mongiello, who has been in the job for nine years. “That is one of those smells you just don’t get used to.”