An Early Fall or Symptoms of Drought?

Anyone who has played the golf course in the last week has probably noticed how many cottonwood leaves have been dropping already.  It isn't even the beginning of September yet, and you would have a difficult time finding your ball in the rough on a few holes (4, 13, 18 for example.)  While we had some chilly mornings of 41 and 42 degrees back in the middle of August, we have not had any frosts yet, leading me to believe that the leaves dropping off the cottonwoods is not a result of the typical passage of fall weather.

Rather, I would assume that this is the result of what has been a long, hot summer.  Cottonwoods are of course a water loving tree that typically grows around rivers and creeks.  Most of the ones we have planted on the course are certainly not in any bodies of water, and are well outside of our irrigation zones.  The cottonwoods dropping their leaves early is their way of trying to survive a drought by shedding their foliage in order to conserve water for the roots. 

Cottonwood going dormant left of 3 fairway

The foliage mess has begun, only 2 more months
of blowing and mulching leaves....

Blowing fairways prior to mowing has started a little early this year
with the cottonwoods dropping their leaves so early.