It’s a gorgeous spring evening in Allston, and the Aeronaut Beer Garden on Western Avenue is slowly filling up with patrons eager to drink in the sun — and some very tasty beverages.

Now in its fourth year, Aeronaut Allston has become a local rite of spring and summer, along with similar spots run by breweries like Trillium and Night Shift. But this year, as the fleeting beer garden season gets underway, the future looks murky.

“If we were limited 14 days in a four-month season, it would make this not a viable thing to do,” said Ronn Friedlander, the co-founder of Somerville-based Aeronaut Brewing Co.

Friedlander is referring to a proposed change in the way beer gardens like Aeronaut operate. Because seasonal liquor licenses aren’t available in Boston, thanks to a decades-old state law that bans the city from issuing them, Aeronaut currently obtains a series of one-day licenses that let it operate three days a week, from May through September.

Now, however, legislation pending at the State House would cap the number of one-day licenses that can be issued to any entity or collection of individuals representing that entity to 14. And if that happens, Friedlander said, “A lot of these places would be forced to shut down.”

In some quarters — like, say, outdoor beer gardens —that scenario has made State Sen. Nick Collins a pretty unpopular guy.

“I think people thought I didn’t like beer!” Collins said of the backlash sparked by Senate Bill No. 158, which he’s co-sponsoring. “Totally wrong.

"Anyone who knows me," Collins added, "knows that not only do I like beer gardens, I like to have fun.”

As Collins explains it, he decided to back the legislation in question after a constituent took issue with another beer garden, run by Nantucket’s Cisco Brewers, that popped up in the Seaport last year.

“They thought it was a little bit odd that there wasn’t a hearing,” Collins said of the constituent in question, whom he described as a public-process devotee. “It’s common sense: you want a seasonal license, predictability for the consumer, predictability for the proprietor, and a fair hearing to know what the public’s about to consume.”

But while Collins insists he’s got no beef with beer gardens, another supporter of the bill does.

“Last year we had almost 19, and they were right in front of front door of our restaurants,” said Bob Luz, the president and CEO of the Massachusetts Restaurant Association.

Luz actually wrote the proposed legislation, which was filed by State Sen. Edward Kennedy of Lowell. His motivation? According to Luz, places like Aeronaut Allston are siphoning business away from existing brick-and-mortar establishments.

“That’s legislation that’s been filed in order to protect people that have invested a lot of money year round, employees that work in those places,” Luz said.

At Aeronaut Allston, though, Ronn Friedlander paints a very different picture of the effect seasonal beer gardens can have.

“They kind of bring people into underutilized spaces. They’re a positive economic impact on the businesss around them, at least in our experience,” Friedlander said.

In fact, Friedlander says, a survey Aeronaut conducted in Arlington, where it operates a second outdoor beer garden, found that most patrons came to that town because of Aeronaut's operation there — and then spent nearly $60 per person at other establishments during their visit.

“It doesn’t always have to be a zero-sum, competitive thing," he said.