Pete - the Radio Reference database for Brunswick County appears relatively accurate for the county's conventional public safety channels, so I'd program the county fire and EMS channels for monitoring activity in Holden Beach ...
http://radioreference.com/modules.php?name=RR&ctid=1896
Tri Beach Fire Department is station 8. Here's a link to a list of all county stations, courtesy of CarolinasFirePage, a notification network for both Carolinas ...
http://www.carolinasfirepage.com/fr_page_1.html
The Radio Reference database does need updating with regards to Brunswick County's plans to migrate to a combination VHF / UHF trunked system. Some of the license / callsgin information, along with site locations and frequencies is no longer valid.
Although the RR information mentions a report of the trunked system in use in 2003, I have seen no reports elsewhere of it being in use, or what type trunking will be used.
Since I know you'll be using a Uniden BC250 scanner, I would suggest that you program all the conventional frequencies you choose with the proper PL tone. This time of year, tropo is common, and your coastal location will make the tropo more-likely.
Using the PL tone feature will help screen other agencies using the same frequencies. Even so, you may hear Berkeley Co, S.C. sheriffs on the Brunswick Co EMS dispatch channel (155.745 / 186.2), as they both use the same freq and tone.
In case you want to monitor the licensed trunked frequencies for activity, the callsigns for the licenses covering a site in Holden Beach are -
WQAT646
WPXM613
There are also two licenses covering sites in Brunswick County, other than Holden Beach -
WQAT670
WPYG263
Here's a link for callsign searches on the FCC database (simply enter the callsign you want to look at):
http://svartifoss2.fcc.gov/cgi-bin/ws.exe/genmen/callsign.hts
I hope the above information helps. Please let the forum know if you note any trunked activity or control channels among the frequencies licensed for Brunswick County.
And have a good time at the beach. I just got back from St Pete Beach, Fla ... the Mrs does all the driving, and I do all the scanning !
Jeff Multer
Fort Mill, S.C.