For What It Is Worth...

Sure is a quite a list to pick from. Not being familiar with the turf I might use these criteria to thin the herd:

1. Unique or interesting structures
2. Anchor industries
3. Prototypes that have interesting spur/switching arrangements
4. Include the non-coal, non-oil industries for variety since coal and oil dominate
5. Any specific company(s) that has a particular meaning or memory with you
6. Availability of look alike structure kits/components if not scratch building
7. Personal taste - one focal point industry with remainder in a supporting role (i.e. big refinery complex at center stage)

What scale?

I may have missed an earlier post but what scale are you modeling?  Your Waterton location is 22 feet but how deep?

There are 28 locations listed for Waterton alone.  Many of those industries would require a lot of space but there are only 5 or 6 industries.  Pick one company for each industry.  With this approach each could be a modest but believable size allowing for a multiple tracks and a number of cars for operations.

Bob

Scale is HO

 Bob,

Sorry...  The scale is HO, and the width of Watertown is 36", but I'm trying to keep the track as close to 24" deep as possible.  I also have a A/D track and three single-ended yard tracks here.  Will also put in an engine house and possibly a small turntable.  My thought process is that the traffic from my staging yards would stop at Watertown and drop the cars for the other two cities.  Then a local would run the freight down to the cities and take care of spotting everything.

LKandO, thanks for the good criteria for choosing the industries!

Ryan

some other considerations

Focus on those industries immediately adjacent to the main track (you have only a couple of hundred scale feet of depth to work with).  More distant industries can (but need not) be suggested/simulated by staging track(s) and/or backdrops.

Reduce duplicate industries.   For example, if there are six coal dealers in one town, winnow it down to two being modeled.

Are all of those individually

Are all of those individually served with their own tracks or do many of them use a common facility or the team track?

Chances are a bunch of them are all the same or served by the team track.

Otherwise I agree with one previous poster. There are a lot of oil and coal dealers listed in the one town. If they are actually all separate, and not just served on the team track, instead of 6 or 8 of each, get rid of half or more of them and just include two or three in appropriate spots to get the proper overall feel.