Way to avoid water turning into land?

[MobRules]

I tried to use the 'depress' terraforming tool to tweak a shoreline. But all the surrounding water turned to land, at the same level as the water was. Trying to fix it by lowering the edges causes the dry area to expand. If I lower it enough, I can fill the basin with water using the terraforming tool -- but it's still surrounded on all sides by land.

So it looks like that if I use a "depress" or "increase" tool on a shoreline, the only way to fix it is to depress every single connected water tile, then fill the resulting basin with water.

(I even tried moving my land-cancer towards deep water, to see if deep water broke the turn-to-land thing, but deep water turns to land at the same level of the water surface as well).

Is there a way that I can fix this (turn everything that used to be water before it was lowered, back into water) without going back to an older save? Also, is there a way I can terraform near shorelines without causing all the adjacent water to dry up?

I tried to find an existing post on this issue, but my search-fu failed me.

[Leartin]

It should work on any shorelines that are one higher than water level, if you bring those down to water level, they should turn into water.
However, if the shore is already flat, you cannot do that. You would either need to heighten it above water level, and then flat it down, or just use the water climate tool (if available) to turn it into water.

[MobRules]

Not sure what I'm doing wrong, then :/

Lowering turns the surrounding tiles to land, raising than lowering turns all surrounding tiles to land. The only tool that I've been able to get to add water (rather than remove it)  is the "fill basin" tool, but it only fills the areas I've manually depressed, not the water-surface-transformed-to-land. (The "ocean biome" tool doesn't seem to do anything at all, even as public player.)

It's counter-intuitive that lowering a shoreline causes the water to retreat from it and dry up.

EDIT: Ah, raising-then-lowering the water-surface-transformed-to-land did work! I was confused because the tiles I tried it on before had some corners above water level and some corners at water level; I was trying things from the wrong corners.

Thanks!!

[Leartin]

The "ocean biome" tool doesn't seem to do anything at all, even as public player.

You probably tried to use it on slopes, while it only works on flat land.