The Moses Lake area can get hot, that's for sure... but make no mistake about it, it is possible to grow a grassy yard. I think, in fact, that probably 95% of people do have grass yards.
No pictures of Moses Lake yet, but here is a link to some
NCWpics.com pictures of Ephrata which is about 20-25 miles away, and the terrain is much the same.
This photo is taken near Wenatchee, WA.
One thing people should know about Central and North Central Washington. While it can get hot here in the summer, with all the hydroelectric dams on the Columbia River, this is probably one of the most irrigated (see photo below) areas in the entire United States. There are man-made lakes and widenings from the dammed up river everywhere... great for irrigation and recreation... not to mention VERY affordable power bills.
Again it is hot and dry... but lack of water is not usually a problem at all.