I can't pick up any NPS traffic from my location, so I can't tell anyone much in regard to the most up to date specifics. I'm not traveling as much as I used to either so my NPS listening is at an all time low. I'm laid up now with a hip fracture and have realized that I haven't been in Yosemite NP at all this year, as the season just got away from me. By the time I'm up and around the passes will be closed and it will be an 8-10 hour trip into Yosemite, and I've only done that one when I was getting paid to do it. I think this is only the second year out of the 27 years I lived here that I haven't visited Yosemite. I do see posts about eastern U.S. NPS units using P25. All federal agencies are supposed to be using radios capable of P25, although I haven't heard the USFS using P25 at all. There are reports (on RR) that Suguaro NP and Chiricahua NM are using P25 full time.
For many years 168.350 was the tactical in many parks. More often than not, it was the only federal simplex frequency in NPS radios, besides the repeater simplex or talk around frequency. 163.100 was sometimes in their radios also, but use of this frequency was less common. With all the new frequencies available due to narrowbanding, many parks are getting unique frequencies assigned to them for tactical use. The frequencies that are replacing 168.350 and 163.100 are starting to show up in a few National Park channel plans that I have managed to get access to in the last couple of years. Those frequencies are: 168.6125 and 163.7125.
As for the channel plan and use in National Parks, they vary depending on the Park's workload and complexity. Some have a bit of functional splitting of nets and some have geographical splits. One example is Sequoia-Kings Canyon's frontcounty and backcountry nets. This reflects the Park's organization as well, with Ranger Districts that use the same split in both function and geography. Yosemite has a Park Net, Valley Net, and a Fire Net. Yosemite has a law enforcement net also, although I'm not sure of how it is used, in relation to the other nets, as the frequency appears to be a closely guarded secret, so I've never monitored it. Yellowstone has a north, south, and west net. Grand Canyon has a fire net and in that case fire is dispatched by an interagency dispatch center located at the Forest Supervisor's Office of the Kaibab National Forest in Williams, Arizona. All other dispatching is done by the Park Service at their south rim headquarters. Almost all parks have adjacent National Forest or BLM Field Office nets in their channel lineup and some have CDF as well. Some have the local sheriff department in their radios.
Smaller park units such as Pinnacles and Point Reyes only have one net, and probably have one of the standard federal itinerants for a tactical. I don't see this changing.
One factor in park workload that can affect radio system design on a National Park is the type of jurisdiction it has. There are some parks with exclusive jurisdiction, or "federal islands" as they are sometimes called. In this situation state and local authorities have no jurisdiction inside the park, except for those given to them by the Clean Drinking Water Act and the Clean Air Act, both passed by Congress in the 1970's. Exclusive jurisdictions are usually found at the large and older parks. National Monuments administered by the Park Service, National Seashores, and other smaller units usually have either a concurrent jurisdiction, where both the federal government and state and local agencies share jurisdiction. Finally there are proprietorial jurisdictions where the land management agency has authority over the resources and land use, while the state and local agencies have authority over criminal and civil law. Ironically, due to its long standing designation as a National Monument until 1994, Death Valley National Park, the largest National Park in the lower 48, has a concurrent jurisdiction. When a park has exclusive jurisdiction, all law enforcement, EMS, and search and rescue is provided by the Park Service, which results in more radio traffic on the NPS radio system. Large parks usually have their own 911 Public Service Answering Point (PSAP) located in their dispatch center, thus routing all 911 calls inside the park to the NPS.
People not familiar with natural resource agencies often submit information where they will list frequency use for National Parks and National Forests as "Rangers." I don't know of any parks that have a frequency segregated just for "ranger" use. In the Park Service there are three primary divisions or branches that use people in the Park Ranger occupational series, protection (law enforcement, EMS, search and rescue), interpretation (campfire programs, nature hikes, visitor centers), and resource management (wildlife, botany, archeology, special uses, forestry, etc.). Each of these have people in other occupational series such as technicians. You can have forestry technicians, biological technicians, archeological technicians and such. Then there is the maintenance division with heavy equipment operators, plumbers, sewer and water plant operators, carpenters, painters, etc. They wear uniforms that don't have a badge and everything on the face of the shirt is a patch. All the rangers except commissioned peace officers, as well as uniformed technicians, wear the same standard NPS badge. Recently, due to changes in regulation and law, commissioned LEO's have started wearing a law enforcement badge. Up until a few years ago they wore the same badge as everyone else, but requirements for armed officers now include a numbered badge to be worn, and not just carried by officers in their wallets. In most parks all of the divisions use the same radio net and it is called "Park Net." I only recall two parks that have a separate fire net and they are Yosemite and Grand Canyon.
Giving each function or division their own net does not have much support as all the tasks are very interrelated, and doing so tends to cause the divisions to not work as a common team as well. Protection rangers need to hear maintenance, resource, and interpretation traffic as it often includes information that affects their function as well as all the other functions. One example being the communications of resource managers concerning bears, having some relevance with the calls protection rangers get for bears being in campgrounds making their "raids."
Many of the larger parks now have unique air to ground frequencies assigned to them that are not one of the seven NIFC air tactical channels and are not shared with adjacent National Forests or BLM Field Offices. Some of the larger parks have quite a bit of S & R and EMS activity that involves helicopter use and they want their own frequency for it, that isn't subject to use on fires on adjacent jurisdictions. Grand Canyon has so many S & R and EMS incidents throughout the year that they have the only "dry lease" helicopter in the western U.S. that I'm aware of. The NPS has their own pilot and provides the fuel with the contractor not providing any day to day personnel with the ship.
Many years ago Park Service radios were set up with Channel 1 being the repeater access, with Channel 2 being simplex. Forest Service radios were the opposite. Now it seems that the Park Service has gone with Channel 1 being the simplex, or in the case of multiple nets, the simplex always being the lower channel or the one listed first, then repeater channels being second, or higher in channel number. The Park Service also tended to provide individual repeater selection by varying the input channel and setting up different channels for each repeater, that all shared a common repeater output frequency. A real inefficient use of frequency spectrum! The Forest Service usually has a larger area to administer, so they used geographical separation to reduce bringing up two repeaters at the same time or had repeaters located in lookouts, where the lookout manually turned on the repeater in response to a field unit's request. The problem was that when the lookout wasn't staffed you had no access to that repeater. You still see some use of different repeater inputs in some parks, even though they have gone to CTCSS selection for repeater access. Looking at the RR database you see this at Yosemite NP where the Wawona and Crane Flat Park Net repeaters share a common input frequency that is different than the Mt. Hoffman Park Net repeater.
All of the large parks used to have everything on one net and that got to be pretty tough to manage, especially when a good portion of the radio users are seasonal employees who often don't have much experience in efficient radio use and protocol. That is one of the reasons you have seen geographical and fire net splitting in the last 10-20 years.
This is a lot of rambling in an attempt to answer the original question and questions that may arise from the answer to that question, which was a very broad question to begin with. Any questions?
