Were this a matter of simple mathematics, the city of Manchester would fork over the $123,300 that Maple Street residents Josh and Allison Greenstein are demanding.

After all, the sum is a lot less than the $1 million that city officials plan to spend on several stopgap measures to keep raging stormwater from further damaging the couple’s property (and blood pressure). They’ve weathered damaging floods four times in the last two years.

And even if their neighbors who are in similar circumstances — there are at least three — made similar demands, the city would end up a little bit ahead.

But the city has rejected the Greensteins’ demands. (The couple made them earlier this month in a letter with legal citations and arguments.)

Rather, the official in charge of the city’s stormwater and sewer systems said he expects the $1 million project on Maple Street and surrounding streets will be completed by year’s end. The work involves higher curbs, more storm drains, street crowning and nearly doubling the size of a buried eight-inch pipe currently in place to handle storm runoff.

“That sounds like a promising change,” Greenstein said. “First and foremost, we want the flooding stopped.”

Greenstein has become adept at generating media interest in what he claims is the city’s inability to protect his two-bedroom home after heavy rains.

Reporters, city officials and firefighters have visited his home during lashing storms. He delineates the high-water marks on his cellar wall and furnace. He has created PowerPoint presentations to show the impact.

His credibility rose as quickly as floodwaters during a July 17 storm when city workers, armed with pumps and sandbags, could not control the floodwaters.

“(Until then), the attitude was always there was no quick fix and climate change was the cause,” Greenstein said. “Someone somewhere gave them the wrath of God.”

Long-term residents say the area has flooded before, but not as frequently as now.

“The No. 1 contributing factor to our problems here is climate change,” said Fred McNeill, the chief engineer in the city’s wastewater and stormwater system.

Climate change has spawned three 100-year storms in Manchester since 2005, he said. And storms such as Sandy, Harvey and Katrina have caused problems across the United States, he said.

McNeill said other factors include the increase in impervious surfaces such as driveways, rooftops and streets which don’t absorb water, and the age of the city’s 380 miles of sewer pipes. Many were installed in the 1930s, and most are only eight inches in diameter.

The city is addressing the problem through two EPA-mandated programs that require maintenance of existing systems and separation of storm and sewer pipes. But that will take time.

It took 10 years to separate sewers on the West Side. It will take 40 years on the east side of the river, he said.

But will it fix Maple Street?

Residents say stormwater runs down Webster Street and onto Maple. The water quickly overflows storm drains. Driveways become riverbeds and water rushes into their backyards with whitewater ferocity.

Renee Daniels said the last storm ripped up her front yard, pushed in a privacy fence and moved an outdoor tool shed a foot. Once the water climbs high enough, it seeps into the cellars, rising perilously close to electrical panels.

Washers, dryers, furnaces, freezers have been damaged. When the floodwaters subside, cigarette butts and other street litter remain.

Greenstein said it’s odd how Washington officials deny climate change, but Manchester officials embrace it when they need an explanation.

“It’s comical,” said Greenstein, a television engineer, who said he believes climate change is real, but doubts whether it is to blame here.

“My feeling is the DPW doesn’t know what the problem is.” He shows me the picture of a catch basin at the Manchester VA Medical Center that is higher than surrounding lawn. The problem could be as simple as that, he said.

The Greensteins want the city to pay bills to stabilize their foundation, waterproof the cellar and regrade their property. Daniels said her family is preparing a similar demand.

If McNeill’s solution doesn’t work, the residents are expected to move forward with their claim.

Meanwhile, McNeill said flooding takes place in other areas — a Mammoth Road neighborhood near the CVS pharmacy, Commercial Street, eastern Lake Avenue, Pickering Street and Riverdale Avenue. He needs to talk to aldermen about paying for solutions.

Because while the EPA has ordered cities across the country to maintain and upgrade their systems, the federal government isn’t paying for it.

“They’re failing,” he said, “all over the country.”

Mark Hayward’s City Matters appears Saturday in the New Hampshire Union Leader and UnionLeader.com. He can be reached at mhayward@unionleader.com.