Bob D As long as you surface as many times as you dive you`ll be alive to read these posts.
Can you tell us a bit more about your layout, and what sort of things you're interested in? What era do you model? Is this "water" a river, lakefront or ocean? Are you modelling an urban area, or rural territory?
We've had some discussions here on packing plants and breweries. Both of these could generate a lot of rail traffic, depending on how various materials were brought into and out of the area. However, you wouldn't be likely to find a packing plant in current-day New England, for example.
I've been trying to work a car float into expansion plans for my own layout. This is a low barge that handles short water crossings carrying some small number of rail cars. One big advantage of a car float is the possibility that just about any rail cargo could be on it, so you get a lot of variety. Some people use a car float as a "casette," a mechanism to introduce a new set of cars on to the layout and take another set off during operations. In this case, the float would be removeable, and there might be more than one model float in the room, taking turns at the float terminal. Others model the float as a fixed piece of scenery.
It takes an iron man to play with a toy iron horse.
You could build a New England-style mill with a water wheel on the river side and say it makes textiles.
A freight house might work (just a transfer shed if width is tight).
A metal-working plant would need a lot of electricity and could fill the yard with cars itself.
City Trolley Co power plant, maintenance sheds, and main office.
Westinghouse (washers, dryers, refridgerators, &c)
not an industry: tenement row plus slummy side of town
<begin smirk> Alcoa (Aluminum Company of America) got famous during the 1990s because they successfully got their Congressman to put an amendment onto a utility tax bill that basically said "except for electrons which are used to turn bauxite into aluminum". There ought to be a way to commemorate that event on the layout. <end smirk>
A cereal manufacturer (Kelloggs Jr) might be a thirsty industry.