Nearly a year of discussion by the Denver City Council about how to build more sidewalks and fix many that are crumbling has shifted to a group of policymakers who are charged with putting together a plan.

The Sidewalk Affordability Working Group in coming months will wade through complex financial and legal issues that could result in greater enforcement of a longstanding ordinance that requires property owners to build and maintain the sidewalks out front.

The aim of several City Council members and now the mayor’s office is to couple that stepped-up crackdown on crumbling or missing concrete with more city investment and, possibly, an assistance program to aid homeowners, especially in lower-income neighborhoods. Those plans could rely in part on a new funding stream of millions of dollars a year — or even upwards of $10 million, the sum a city mobility task force plans to recommend for annual sidewalk spending.

How to pay for it? Options include a new fee or tax, though it’s not clear yet if all homeowners would have to pay or how much an assistance program would cost.

The sidewalk working group, created at the behest of Mayor Michael Hancock, met for the first time Thursday behind closed doors. The panel includes representatives from the city attorney’s office, the mayor’s office and the city’s departments of Finance and Public Works, along with Councilmen Paul Kashmann and Jolon Clark.

“It was actually a very encouraging discussion where, for the first time, we had all of the players at the table,” Kashmann said. Over the past year, he chaired a separate council panel that examined Denver’s sidewalk gaps, putting pressure on Hancock to advance an issue that the city estimates it would cost $475 million to tackle, likely over decades.

Public Works officials have estimated that 520 miles of city streets, or nearly 23 percent, have no sidewalks, while another 90 miles or so have a sidewalk on just one side. Many more sections have cracked or pavement shifting stone slabs that make them tough to navigate, especially with strollers and wheelchairs.

Kashmann said the new working group set out a timeline that calls for sending recommendations to the mayor by June for cost-sharing options with homeowners.

Among money-raising ideas that have been mentioned:

A new sidewalk fee. Assessment would be based on the length of property frontage or on square footage of pavement. It could be voluntary, like Englewood’s successful program, asking homeowners to opt-in to qualify for future assistance with repairs.

A property tax increase dedicated to sidewalks. Denver has some untapped taxing capacity remaining for possible activation without a citywide vote because of voters’ 2012 approval of a measure permanently relaxing some rules under the Taxpayer’s Bill of Rights.

One-time borrowing, perhaps as part of next year’s expected package of requests to voters for major bond issuances to raise hundreds of millions of dollars for various city building projects.

City officials also could opt for a multi-pronged approach.

“While I would hope that the 2017 bond issue lends a hand to pedestrian infrastructure as well, we have to have an ongoing funding stream for repairs and installation,” Kashmann said. “My preference would be that it’s some sort of a cost-sharing — whether it’s an opt-in fee or whether it’s a tax.

“From the talks that I’ve been having with the mayor, I would not at all be surprised if he takes a tack of a more broad-ranging infrastructure fee type of a thing.”

Other issues to sort out include whether to leave responsibility with property owners, as city attorneys advise; how to create a stronger enforcement system; what resources Public Works needs to evaluate sidewalks and prioritize assistance; and whether to offer homeowners the option to pay for their share of costs in installments.

Mike Krause, from the libertarian-leaning Independence Institute in Denver, recalled that a basement renovation at its Uptown headquarters resulted in a city order for the group to repair a sidewalk.

He opposed the council’s recent decision to raise $150 million for an affordable housing plan from property taxes and new development impact fees, but he said there was a better argument for a dedicated sidewalk fee or tax. Sidewalks, which serve everyone, are more justifiable as a basic city service, he said.

“So I think Denver might be on the right track if they can figure out some kind of opt-in impact fee,” said Krause, director of the institute’s Local Colorado Project. Even better, he said, would be to make the case to voters for a full-throated citywide tax that raises more money.

Jill Locantore, policy and program director for pedestrian advocacy group WalkDenver, said she’s encouraged by the city’s discussions.

“The ultimate goal that we’re focused on is treating sidewalks like any other type of infrastructure in the city,” she said, in “the same way we treat the streets or the sewer system — where the city takes a comprehensive approach to building a complete network and maintaining that network over time.”