In advance of a Sept. 25 vote by the Federal Communications Commission to ease telecommunication companies’ deployment of 5G wireless networks, the Marin County Board of Supervisors has sent a lengthy letter of opposition. The F.C.C. is seeking to ban state and local regulations designed to prohibit wireless infrastructure deployment and limit the fees cities can charge for reviewing 5G projects. Its order would also establish a 60-day shot-clock—a window of time from an application’s submittal to its approval—for attaching small cells to existing structures and a 90-day one for new builds. The cities of Mill Valley, Petaluma, Ross and San Anselmo have already enacted ordinances to restrict and regulate the installation of 5G cell towers. This week, a wave of residents urged county supervisors to pass a similar ordinance for unincorporated Marin. Tom Lai, deputy director of the Community Development Agency, said that, in unincorporated Marin, “We have regulations and we have been pretty effective—right now, no carrier can just come in without land use approval and put in a new array of 5G in our neighborhoods.” Asked about the effectiveness of county action should the F.C.C. seek to override local resistance, Mr. Lai said county counsel was looking at legal options. On Tuesday, community members flooded the open comment portion of the supervisors meeting, expressing concerns that ranged from health impacts from radio frequencies to infringements on property rights, privacy and local control. Supervisors could not comment because the issue was not on their agenda, but they had sent a critical letter to the F.C.C. the day before. “We oppose this effort to restrict local authority and stymie local innovation, while limiting the obligations providers have to our community,” the letter states. Supervisors described the proposal as “offering the for-profit telecommunications industry a deeply discounted financial arrangement and exceptional use of public assets for limited community benefit.” It continued, “The order touts the economic benefit of faster deployments without acknowledging the costs, and not just from lost permit and rights-of-way fees, but also from impacts to property values/economic development/quality of life if small cell installations are not properly installed or well managed.” The letter encouraged the commission’s wireless bureau to update radio frequency emissions standards for 5G technologies and to clarify liability issues related to small-cell attachment devices. In addition to the public comments on Tuesday, many local groups have mobilized their membership to put pressure on the county. “Telecommunications giants like Verizon and AT&T are basically running roughshod over local property rights and local telecommunications ordinances,” Katharina Sandizell, co-director of West Marin’s Alliance for Human and Environmental Health, said in a press release. “Our local governments are supposed to protect their constituents from profit driven corporations installing cell towers on every other utility pole without property owners’ knowledge, informed consent, or democratic process. We didn’t elect our local officials to sit back and do nothing.”