This text was supplied by Michel Verheughe firstname.lastname@example.org
"Unofficial" texts are member contributions that have not yet been discussed or approved by the ESP community.
How to make rivers.
Rivers and lakes are best made in the same way you trace coastlines.To make a river, first try to find its path on the ENV file, from one edge to the other edge. Remember that World Maker doesn't show a Mercator projection, so it might me a mismatch between what you see on your map, and how it should be on the ENV file in World Maker.
Click on the polygons you will use for the river as "Toggle water/land."
Try to follow the lowest elevation (darker shade of green) as much as possible, rivers seldom run on the top of hills. Once you are pleased with the path, start moving the polygon nodes on both side of the river so that it gets the width it should have. In the process, try to rectify nearby polygons that may get an odd shape.
Remember that, as much as possible, the polygons should keep a square shape so that they display textures in a nice way.
Once the ENV file is finished, you can continue with the next. To do that, you should count the number of polygons at one edge and pick the same one on the next ENV file. Note that you cannot make the edge polygon narrow so it will always look a bit strange at the intersection of 2 ENV files, but that's the way it is.
When finished, you can level the river with the Auto-level function but it is not easy. If the river is at about the same elevation all the way, you may use
FlatSea II (Mac only) that will flatten it (and the sea and lakes) for you at the level you wish (user input).
To finish, you can leave it like that, or cover it with "alternative water" texture, to give it another colour.