Topographic Oddity

I own land on the edge of a sim with a fairly high water table. The level of the land (and the water) in the neighbouring sim is well below the water level on this sim, so where they meet... odd things happen.
When I first bought the land, the terrain was higher on my parcel to kind of hide the differential, but where it sloped down to meet terrain of the neighbouring sim, the water stuck out like a cube of strange-coloured jello.
I am pretty thrilled with having the water level so high, because it let me terraform to make a really neat water feature. But I'm still stuck with the weird, gelatinous, solid-water effect on the sim edge. I've put some prim rocks and a wall there to make it less obvious (and so it feels less like I'm swimming in a fishbowl), but it seems like there should be some sort of more elegant solution. Suggestions?
In a related question: if, at some point in the future, I am able to acquire the adjacent land on the other sim, would I be able to join the two parcels? Can you join land across sims?

First, the simpler answer - As far as I know you cannot join land between sims; Tis a limitation on how they work. Also, prims between them will allocate by the sim (i.e. 1024 side will have a set amount of prims and the 2048 side will have another, not a shared prim set @ 3092). Only advantage in this is the ability to have twice as many people over (across the sim boundry).

In regards to the other question - What two sims are these? By your wording this is the mainland, and they all tended to have the same water level.

This may be a mistake by LL, depending on which sim it is. You may want to post a request in the Second Life Land Management or even SL Answers.

I hope this helps. *link*

I took some snapshots last night while on SL, and since today was slow at work, I put them up here:
http://www.lovelymachine.com/SL/

The two sims are Castaneae and Lupulinus. It's <i>really</i> obvious in the map shot on the webpage (at least to me). I honestly hope it's not a LL mistake that would be "fixed" by dropping the water level in Castaneae, since I rather like having it close to the surface. Now that I think of it, there's not really any other way for them to fix it, is there? Hmm. Forget I said anything. I can just put some trees in front of it and no one will ever know the difference!