Flight Instructor reported the CTAF/UNICOM frequency at the non-towered U76 Airport provides the weather advisory broadcast as well as control over the airfield lighting at the airport; and also shares that same frequency with several other surrounding airports. This results in frequency congestion and along with the growing traffic at U76; creates the potential for a conflict in the traffic pattern.

Narrative

The automated weather station at U76 transmits its weather advisories on 122.8 MHz; the airport's UNICOM/CTAF frequency. It is currently NOTAMed as 'winds unreliable;' rendering it essentially useless for advisories. The system is designed to provide a weather advisory when a pilot clicks the mic 3 times on 122.8. It will provide an extended advisory broadcast if the mic is rekeyed immediately after the end of the first advisory transmission. It also provides an option for a radio check when a pilot clicks the mic 4 times. This is the same frequency used for controlling the intensity of the airfield lighting (runway; taxiway; and PAPI lights). My student and I taxied from the departure end of Runway 10 at U76 to the approach end of 10 for takeoff. After announcing our taxi intentions; the weather station began transmitting the weather advisory. Immediately following this advisory; an inbound aircraft keyed the mic 3 times; setting off the weather station's extended advisory. Apparently; the inbound pilot did not hear what was desired and rekeyed the mic a second time; resulting in a third weather advisory broadcast.Perhaps a pilot at a surrounding airport that uses the same CTAF/UNICOM frequency stepped on the weather advisory; which is a common occurrence. This weather station transmission is additive to the frequency congestion caused by having the Gooding (44 miles); Jerome (62 miles); Ontario (90 miles); and McCall (110 miles); as well as others within radio range; all on the same 122.8 MHz CTAF/UNICOM frequency. While the weather station and traffic at these other airports are transmitting; traffic at the Mountain Home Airport cannot transmit their locations and intentions. This creates the potential for a conflict in the traffic pattern at Mountain Home. The Mountain Home Airport personnel are aware of this concern but have dismissed it because the FAA and the state aeronautics division have not spoken to them personally about the issue; despite state aeronautics personnel specifically highlighting the Mountain Home Airport's frequency congestion problem at the last 2 annual statewide safety stand-down events. This problem continues to grow as the traffic at the Mountain Home Airport increases and traffic patterns become nonstandard with the addition of helicopters and crop dusting aircraft.