It’s not often that a city has the chance to vote whether to flush nearly $4 billion in economic activity down the toilet, eliminate tens of thousands of jobs, and throw away $70 million tax dollars per year — with effects lasting as long as 10 years.

Even more rarely does the opportunity come to drive housing costs farther out of range for the middle class.

However, a report from Beacon Economics on the economic impact of Measure S, the so-called Neighborhood Integrity Initiative scheduled for the March 7 ballot, suggests that Los Angeles voters will face exactly that choice in the 2017 city election.

Measure S declares a ban on any new building that requires zoning changes or General Plan amendments.

With the least affordable rents in the United States, Los Angeles needs thousands of new units of housing to ease its housing crisis. Many of those can only be realized with the help of such zoning changes. Our planning documents are badly out of date, and our city can’t afford to sit on its hands while we update them.

Measure S’s backers claim it will force Los Angeles to update its plans during the period of the ban — but instead of providing the funds to do that, the initiative shrinks our economy, slashes jobs, makes rents higher and homelessness worse, and starves the public of needed funds.

After reviewing permit data, Beacon concluded that the ban would shrink L.A.’s economy by $3.8 billion in two years. Construction spending and the services it supports would dry up. The effects would ripple out, hurting spending throughout the local economy.

The brunt of that pain would be felt by construction workers — both the current workers who would be out of a job and the future workers who would never have the chance to put their foot on the first rung of the ladder to the middle class. Two years of Measure S would cost 13,800 of those jobs, and ripple effects would bring that job loss to more than 24,000 citywide. The loss in wages would top $1.2 billion.

At the same time that this housing ban punishes the economic activity of ordinary Angelenos, it would also starve the city of the revenue that construction brings — such as permit fees, Quimby fees (for parks) and Finn fees (for schools). Sales, property taxes and hotel taxes would all diminish. A single year of banning construction would sacrifice $70 million from the public treasury — enough, as Beacon points out, to hire 1,000 new police officers or firefighters.

And though it’s written as a two-year ban, loopholes and poison pills written into the law could drag it out for up to 10 years, costing billions more. Our housing and our economy could take more than a decade to recover.

It’s hard to point to any one of Measure S’s impacts and call it the worst effect of all. But its effect on Angelenos trying to make their rent may have to do.

Our economic recovery is fragile. Our renters are disproportionately “rent-burdened,” with 270,000 Angeleno households paying half or more of their income in rent.

Measure S prevents us from building the housing we need to turn the tide of the housing crisis. The new apartments that will ease competition for scarce units — gone. The mixed-income apartments, built with the kind of inclusive agreements that often follow zoning changes — gone. And it’s not hard to see how pulling $3.8 billion in wages out of the economy will push a number of Angelenos over the edge into homelessness.

Worst of all, the very housing that Los Angeles voters demanded we build for the homeless with last November’s Prop HHH could not be built. Measure S claims to have an exemption for 100 percent affordable housing — but Measure S bans construction on 90 percent of city-owned sites proposed for affordable housing.

As representatives of Los Angeles’s business and labor communities, we often take opposite sides on election day. But we will always unite to defend the economic health of our city and its middle class. There’s no greater threat to that health than Measure S on the March 7 ballot.

Gary Toebben is president & CEO of the Chamber of Commerce of Greater Los Angeles. Ron Miller is executive secretary of the Los Angeles/Orange Counties Building & Construction Trades Council.