You have two major choices when placing a waterway. Do you want to create a Lake, or a River.
Lakes will cost 2pp(small), 3pp(medium), and 4pp(large), and default to medium size if not specified. When placing a lake, you must say what hex you wish to put the lake in, and in what general area you wish the lake to be. Location Examples: outer edge between xx.xx and xx.xx hex, near the middle of xx.xx, northwestern corner of xx.xx, southern edge of xx.xx, just below the center of xx.xx, etc.
Rivers must be placed either between a lake and the ocean, or between a higher elevation(hills, mountain, high mountains), and a lake or the ocean. You must choose the thickness of the river you decide to place, choices being: stream(thin), river(thick), canal(thicker). Thickness is a cosmetic choice only, and defaults to river. The same sort of location suggestions are advised when posting a river action, you will pay 2pp for every hex the river goes through, for a minimum of 2pp.
Tectonic events also remain, but now cost 40pp each. And both destroy water features if used within the effective range.
Note: Special effects of tectonic events cannot have either waterway added within that hex.
There are two special events you can choose to use if you spend the higher pp cost.
Volcanic Eruption or Plate Collapse
They do basically the same thing, but are opposites of each other. A volcano will create an area of shifted elevation upward, while the plate collapse lowers the elevation around the hex chosen.
Each event effects multiple hexes, I roll 1d12 to determin how many hexes are effected.
These events will always occur at the end of a turn, and will always win a conflict roll.
They also produce extra terrain types, Eruptions will produce volcanos or lava, while Collapses produce canyons or whirlpools. There will be a dice roll based on how many hexes the event effects, for example: If the effect d12 gives me 6 tiles, I would roll 1d7. a roll of 1-6 would give me that many extra terrain tiles, while a roll of 7 would give me 0. What type of extra, and placement of them is GM choice. I'll probably just scatter them some around the effected area.
Extra terrain types now cost 5 points to change back into a normal terrain type. Whirlpools turn into Ocean, Canyons and Lava turn into Land, Volcanos turn into Mountains.
Waterway Extras:
The main waterway events are either Rapids or Waterfalls, both must be placed on an existing river. During this age, these events are merely cosmetic, but may come into play during the advanced stages
Waterfalls occur only in a higher elevation(hills, mountain, high mountains). They cost 15 points.
Rapids can be placed on any hex that contains a river, and also cost 15pp.
You may also purchase a river crossing at 10pp. This being a small pinch in the river that will allow land crossing without blocking the river.
The locations of all waterway actions should be described as best as possible when you purchase them. However, I will use my best judgement when plotting things out. Therefore I may not always get it exactly where you want, but I will do my best.