Notes from the foothills.

A canyon with one road out and thin cell coverage is a familiar setup in the Calaveras and Tuolumne foothills. It is also the exact problem two mountain communities elsewhere have been solving with volunteer radio, and their networks are worth a look at the height of fire season — because the part that makes them work is not the equipment.

The fast part, and the slow part

In May, residents of Weber Canyon in Utah’s Summit County switched on a solar-powered GMRS repeater built on a donated half-century-old television tower on the canyon’s northern ridgeline. GMRS — the General Mobile Radio Service, a licensed UHF two-way band — carries voice between handhelds with no cell tower in the path, and a single ridgeline repeater extends that range across a whole watershed; the Weber Canyon net now reaches out to Oakley, Kamas, and Park City. The project began after a resident watched a documentary about the 2018 Camp Fire and recognized his own canyon in it: sparse cell service, one way in and out. The license is a flat $35 for ten years, no exam, and the repeater itself needed FCC approval.

The radio was the fast part. About 30 people now check in on a monthly roll call — first Tuesday, 8 p.m. That standing net is the point. A radio that has sat in a drawer since the day it was bought is not a communications plan; a group that keys up together every month, on a known channel at a known time, is. The roll call is where a member learns whether their handheld actually reaches the repeater from their own property — which is not something to find out during an evacuation.

The longer proof

California’s own fire country has the longer-running version. After the 2015 Valley Fire destroyed 1,300 structures and killed 4 people in Lake County, survivors in Cobb built the Cobb Alert Net, documented by the Fire Adapted Communities Learning Network. It now counts 270 participants across 85 square miles and 7 hamlets, organized in three tiers: a small core of licensed amateur (“ham”) radio operators, 34 GMRS operators who serve as neighborhood leaders, and residents who use the simplest license-free Family Radio Service walkie-talkies. It practices weekly, 20 to 60 minutes at a time.

The tiers are what let it scale. A neighbor can join at whatever level they are ready for — an FRS radio off a store shelf, a $35 GMRS license, or a full ham ticket — without being left out of the net. Nobody has to clear the highest bar to be reachable.

What carries across

Two things translate to the Highway 4 and Highway 49 corridors. First, the hardware is the cheap, quick part; the network is the people who practice with it. Second, both nets were built deliberately, before the season they were meant for — the same order of operations as clearing defensible space or packing a go-bag. A GMRS license covers an entire household and takes no exam, which makes it the low doorway in. The higher-value step is finding out whether your road, ridge, or water district already runs a net. In Calaveras County, one already does: the Ebbetts Radio Safety Net, the volunteer GMRS net that S.I.E.R.R.A grew out of, holds three practice nets a week — Monday out of Murphys, Wednesday and Saturday out of Arnold. Where no such net exists yet, a handful of neighbors and one repeater is all Cobb and Weber Canyon started with.

Both communities stood up their nets in an ordinary month rather than a dangerous one. The monthly or weekly schedule is what turned a pile of radios into a network that answers.

PG&E cut power to about 7,800 customers across 10 counties on July 15 — the utility’s third Public Safety Power Shutoff of the year. Calaveras and Tuolumne weren’t on that list, but both counties sit in the same Tier 2 and Tier 3 high fire-threat districts PG&E uses to decide who goes next when wind, low humidity, and dry fuel line up. That puts a shutoff reaching the Highway 4 or Highway 49 corridor well within reach this season — worth planning around before an outage starts, not after.

The backup clock

A 2020 California Public Utilities Commission decision requires wireless carriers to keep cell sites in Tier 2 and Tier 3 high fire-threat districts running on backup power for at least 72 hours after the grid goes down — enough to hold 911 access, emergency alerts, and basic connectivity through a typical shutoff. That is a real, enforceable floor.

It is also just a floor. PG&E’s own July 15 shutoff notice is candid that outage length depends on real-time weather, damage assessments, and the patrols and repairs needed before lines are safe to re-energize — and in steep terrain, that inspection can take longer than flat ground. When a shutoff runs past 72 hours, the backup clock at the cell site runs out before the grid comes back, whether or not anything else goes wrong.

What closes the gap

None of this needs to be solved in the moment. A few things are worth having ready before a Red Flag forecast, not after the outage starts:

• A battery or hand-crank radio that receives NOAA Weather Radio or standard AM/FM. It pulls official alerts straight off the air, with no cell tower, account, or app in the chain.
• A charged battery bank or a small solar panel, topped off ahead of a forecast wind event rather than found dead when the power drops.
• A GMRS radio. The FCC license is a flat $35 for ten years, with no exam, covers an entire household under one callsign, and talks radio-to-radio between family, neighbors, and vehicles without touching the phone network at all.

PG&E posts a rolling 7-day PSPS outlook and address-level shutoff status once a watch is called — that page is the one to check as conditions build, not a blog post written days or weeks ahead of the next event. The backup-power window is generous. It is still a window, and the plan for what happens after it closes is the part worth having ready now.

An evacuation order names a zone, not a street or a town. When a Sheriff’s Office issues one, it points to a zone code drawn on a map ahead of time — and if that code is unfamiliar, the middle of an incident is the wrong moment to work out whether it means you. It costs nothing to know it early.

What a zone is

An evacuation zone is a geographic boundary drawn in advance by local emergency officials, not improvised during an incident. Calaveras County’s Office of Emergency Services and Sheriff’s Office maintain zones through Genasys Protect (formerly Zonehaven), the same public lookup tool used by dozens of California counties. Enter an address at protect.genasys.com and it returns a zone ID, plus that zone’s current status. Calaveras County’s guidance on what to do with that ID is blunt: write it down somewhere visible, “like on your refrigerator” — it is the name that will show up in an alert, not the street.

Warning and order are not the same word

Cal OES defines exactly two evacuation statuses, and the difference is about time, not severity:

• An evacuation warning means a potential threat exists. It is the signal to get ready — pack, arrange for pets and livestock, account for anyone who needs more time to leave — because an order may follow.
• An evacuation order means an immediate threat. It is a lawful directive to leave, and the area is closed to public access.

The Tuolumne County Sheriff’s Office uses the identical two-tier language, word for word. This is statewide terminology, not a Calaveras-specific system, which is why the same two words apply on both sides of the corridor even where the local zone tools differ.

Where the authority lives

S.I.E.R.R.A does not draw these zones or decide when a warning becomes an order — Sheriffs’ offices and Cal OES do, and only they can issue or lift one. The Live Feed points to Genasys for evacuation status for the same reason: the authoritative record belongs with the agency that issues it, not with anything that mirrors it. When an order comes, it comes from them, and it is the one to act on.

Looking up your zone at Genasys Protect takes under a minute. Doing it now, rather than during the next red flag day, is the entire reason a zone system gets drawn years ahead of the fire it is built for.

Two wildfires burned in the Highway 4 / 49 foothill corridor in early July. Both stayed small, both are now fully contained, and CAL FIRE has resolved both. This is a look back at the official figures, drawn from the same feed the Live Feed uses; there is nothing active to act on here.

Priest Fire — Old Priest Grade at Highway 120, Big Oak Flat (Tuolumne)

Reported on July 6, the Priest Fire reached 9.5 acres, 100% contained, and is resolved. It never grew past about ten acres and was fully contained within a couple of days of ignition. The authoritative record is CAL FIRE’s Priest Fire incident page.

Landrum Fire — Landrum Street, Plymouth (Amador)

Reported on July 4 just off the corridor’s northern edge, the Landrum Fire reached 12.5 acres, 100% contained, and is resolved. It held near full containment for its last days before closing out. The authoritative record is CAL FIRE’s Landrum Fire incident page.

What it shows

Two ignitions, roughly twenty-two acres between them, both held small and contained without significant spread — an unremarkable early-July stretch, which is the good kind. For radio operators and residents, the takeaway is the ordinary one: the tools that matter are the ones you can reach when cell service can’t, and the place to watch conditions in real time is the Live Feed, not a blog post. During either fire, current status lived on CAL FIRE’s incident pages and the Live Feed; for evacuation information the authority is Cal OES / Genasys.

Figures here are CAL FIRE’s final numbers as carried by the S.I.E.R.R.A data feed; where a live incident and a look-back ever disagree, the incident pages above are authoritative.

A repeater running on solar power lives or dies by its power budget. On the shortest days of the year, a panel might see four or five hours of usable light, and every watt the radio spends on housekeeping is a watt not banked for the night. MeshCore’s firmware release 1.16.0, out June 6, trims that housekeeping in a way worth understanding.

MeshCore, the routing protocol behind this kind of off-grid LoRa mesh — a network of radios that relay messages hop by hop when there is no cell tower to carry them — does not flood every packet to every node the way some mesh platforms do. It leans on a smaller number of deliberately placed repeaters holding known paths between them, a design suited to ridgeline terrain where a handful of well-sited relays cover more ground than a dense swarm of cheap nodes could. That design only pays off if the housekeeping traffic between those repeaters stays light. There are fewer of them to split the airtime, and each one runs on stored sun.

The clearest change in 1.16.0 is to that housekeeping. Repeaters periodically send an “advert” — a short broadcast announcing that a node exists and is reachable, which is how the mesh learns and refreshes its routes. The default interval between adverts has been stretched from 12 hours to 47, and a new setting, flood.max.advert, limits how far an advertisement floods by default to 8 hops. In a network where the physical layout of repeaters barely changes week to week, routes do not need refreshing every half day. A repeater keying up roughly four times less often for the same housekeeping is a direct cut in the radio-on time that drains a battery fastest.

The release pairs that with general power-saving work in the ESP32-based repeater firmware, plus an auto-shutdown feature for the battery-powered companion units volunteers carry in the field, one that disables itself automatically when a device is running on external power instead.

None of this changes what a repeater can do. It changes how much of its stored energy goes toward doing it. For a network of solar sites rather than mains-powered towers, that is the more useful kind of firmware update: not a new feature, just a quieter radio.

Curious about the network? Get in touch via the contact page.