Question
I have a stand of about 15, approximately 80 year old, Doug Fir scattered over my 1/2 acre piece of property.  Over the past 15 years 3 trees have died.  The soil is very sandy.  I have never "watered" my trees or anything on this property. My question to you is: should I water my trees?  If so, how much and how often?  I am in Western Washington so I get a lot of rain for 9 months of the year, but for 3 months, not so much (depending on the year).  I am wondering if the trees are competing for the available water/nutrients and so are dying out because of the competition??

Answer
No trees this age and size do not need watering. They have already established and sound root system and this species has a tap root that would grow down for water. There could be many reasons for trees to die. The most common would be insects or diseases. Any change in the ground cover under and around the trees could cause problems. I do not really have enough information to ID what the cause might be. But I would rule out lack of water as a concern. Sorry.