Visited with Mark today while he was here working on an irrigation issue.  We have had problems with flooding in the northeast corner of our lawn.  While trying to take care of the problem we capped off one sprinkler.  It has been brought to our attention that in the fall when they are blowing out the system it is possible that we could have water left in the line and freezing that will then break said line.  What we are looking for is a sprinkler head that we can turn on and off which he said is available.