The Shaniko Butte Fire is now 50 percent contained.  The fire 15 miles north of Warm Springs has burned 42,500 acres.  Firefighters were not able to complete their planned burnout operation Sunday because the relative humidity was too high and horses had grazed the grass too short.  The grass was cropped low and would not carry fire because it was just a little too damp, so the firefighters finally had to stop trying to ignite it.  Crews used the extra time to further improve the line in preparation for later ignition, and also to more thoroughly patrol the river area and extinguish any hot spots that were discovered.  Fire behavior has moderated with higher humidities and lower temperatures with moderate winds.  The Deschutes River was reopened to recreationalists on Sunday.