William Laforet would like to have a conversation with the South Monsey Eruv Association.

Mr. Laforet is the mayor of Mahwah, which last week cited the eruv association for violating its ordinance barring signs on utility polls.

Back in May, he had discovered that strips of half-inch plastic tubing had been placed on utility poles in his town. The same thing was happening in nearby Upper Saddle River and in Montvale. Those three towns, in the northwest corner of Bergen County, are immediately across the border from New York State’s Rockland County.

Mr. Laforet called the Orange and Rockland Utilities, which owns the poles, when he found them. “They explained to me that a permit had been acquired by these people for the placing of these markings on the pole for an eruv, and they had no obligation to notify the communities,” he said.

An eruv is a legal fiction that enables observant Jews to carry in a public area on Shabbat by creating a notional wall consisting of vertical poles — the plastic piping — topped by wires — in this case, the existing utility lines.

So Mr. Laforet called the eruv committee, which coordinates the eruv that encompasses much of Rockland County.

“I left several messages to say I would like to learn more about an eruv, and would like to learn more about their intentions,” he said. “We are a very diverse community. There are some 20 houses of worship in Mahwah. The situation at hand is something we could resolve if get a chance to speak to somebody.”

He explained that under the town’s ordinance banning signs, a sign is defined as “an instrument that attracts your attention and directs you to do something.” He said that the pipes that demarcate the eruv are a sign that the area is enclosed by the eruv, and they direct observant Jews to stay within the perimeter if they wish to carry on Shabbat.

However, similar claims have not fared well in court; previous rulings have said that eruv associations in Tenafly and New York’s Hamptons have First Amendment rights to use the utility poles.

“There’s no way for me to know where any sign violations end up,” Mr. Laforet said. “Generally speaking, residents will take down signs that are noted by the zoning official. That’s been our experience and we hope that’s the case here.”

Public opposition to the eruv in Mahwah has grown since the order to take down the markers were publicized.

More than 1,200 people signed an online petition calling for the eruv to be taken down. Many of the dozens of comments accompanying the petition, titled “Protect the Quality of our Community in Mahwah,” refer to “these people” and express concerns about falling property values. Most of them are anonymous.

“I don’t want these rude, nasty, dirty people who think they can do what they want in our nice town,” one of the comments reads.

Another says: “I do not want the town of Mahwah to turn into an undesirable place to live. These people do not assimilate with other people outside their community. I do not want them controlling our school board and siphoning funds for their yeshivas. Also, they buy houses which they claim is for religious purposes and do not pay taxes. They should stay where they are and leave our town alone.”

Former town Councilman John Roth, who started the petition, told the Bergen Record that he closed it because of the tenor of the comments it attracted.

On Monday night, more than 200 residents gathered to protest the eruv.

“We do not not want these people living in our neighborhoods,” the Orthodox website VosIsNeais.com quoted Mahwah resident Robert Ferguson as telling the meeting. “We want them following the law.”

Mr. Ferguson went on to note that a recent ordinance barred non-residents from using the public park, a measure passed in response to busloads of out-of-state visitors.

He compared the situation in Mahwah to those in Rockland County and in Lakewood, in New Jersey’s Ocean County. In both those places, the growth of large communities of ultra-Orthodox Jews have coincided with repeated deep cuts to public school budgets, and to high and increasing tensions between various groups there.

Sandy Eller, who reported on the gathering for VosIzNeais.com, wrote that as a visibly Orthodox person, “Several people told me I was not welcome during the meeting and I had cell phone cameras shoved inches away from my face repeatedly as people snapped pictures of both me and my press credentials.”

JTA Wire Service contributed to this story