The grass is always greener. . .

Before I edit it.

How can I get the green grass look back on the hillside land land I dug into in order to nestle my house (partly on stilts) and place a waterfall beneath?

Terrain textures look different at various heights. Chances are you dug down and it turned brown. The only way I know to change it back is to raise it back up.

You can fake it with a prim textured with a ground cover. You can find all the default land textures in your library, in the texture folder.

yes if you want to work at that height and have grass, you'll have to cover the ground with a textured object. it may require several prims depending the area you're covering. one nice effect you can create with prim grass is phantoming the object so that people's feet sink down into it. it makes them feel all squishy inside.

if you want to start all over again, click the bulldozer in the edit window, double click the ground so that you select the entire lot, choose "revert" using the radio buttons on the left, and press the "apply to selection" button several times.

Thanks to you both for your replies. Since the waterfall has already been placed. . .and painstakingly tweaked. . .I'll make do with some well-placed ground-hugging plants.