Question
Our community is at 4,500 ft. elevation in CA. with several large Jeffrey & Ponderosa pines.  We have a community well system.  Our latest well was placed in an open field, no trees nearby at all, and is poor-producing.  Someone mentioned that the water would be closer to the pines, as their roots go straight down; their rationale is that if there are no trees, there's no water.  I've heard that some roots do go down deep, but the majority of the water-seeking roots are nearer the surface.  Which is right, and is there any truth to the rationale we'd do better finding water (drilling wells) at least in the area there are trees?

Answer
Mature large ponderosa pine may have a tap root that reaches 60-90 feet deep. Wells are drilled much deeper several hundred feet deep. The majority of the root system is within the first 2 feet of soil but pines have tap roots that extend deeper to with stand drought situations.
The water supply under the ground will depend on the geology not the tree cover. Now natural stands of trees will grow where there is water compared to a desert type environment but the present of trees or not will not be a sure thing that a well will be good there.