here's what i did. I took the cave layout and saved it as a picture, then imported it as a bitmap into the Corel Draw program i usually make maps on. you can find more maps at the Terrainmonkey map showcase thread to see.
When it was on the corel draw, i made 4 layers starting with a light blue, then a bit darker, then a bit darker after that. make the circles smaller and smaller. I grouped them all together and made them 50% transparent. Then, i copied the first layer, the largest one, and did a rough texture effect. that layer was put on top, made transparent and presto, water effect. Then, i drew a line around the outer edge of the pond, lightened it up to the same color as the surrounding rock, and added a drop shadow effect to the line which then gave the pond some additional depth. i'll add another picture of the completed pond in this post to show you the difference.
thanks for the comments. if you want to see more, just let me know.
i've updated the cavern map a bit. just to make it bigger. edit 7/7/06